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diff --git a/old/30495.txt b/old/30495.txt new file mode 100644 index 0000000..37af5ee --- /dev/null +++ b/old/30495.txt @@ -0,0 +1,7989 @@ +The Project Gutenberg EBook of A History of Science, Volume 5(of 5), by +Henry Smith Williams + +This eBook is for the use of anyone anywhere at no cost and with +almost no restrictions whatsoever. You may copy it, give it away or +re-use it under the terms of the Project Gutenberg License included +with this eBook or online at www.gutenberg.org + + +Title: A History of Science, Volume 5(of 5) + Aspects Of Recent Science + +Author: Henry Smith Williams + +Release Date: November 18, 2009 [EBook #30495] + +Language: English + +Character set encoding: ASCII + +*** START OF THIS PROJECT GUTENBERG EBOOK HISTORY OF SCIENCE, V5 *** + + + + +Produced by David Widger with thanks to Google Books + + + + + +A HISTORY OF SCIENCE + +By Henry Smith Williams + +Assisted By Edward H. Williams + +In Five Volumes + + +VOLUME V. + +Aspects Of Recent Science + +New York And London + +Harper And Brothers + +Copyright, 1904, by Harper & Brothers. + +Published November, 1904. + + + +CONTENTS + + + BOOK V + + + CHAPTER I--THE BRITISH MUSEUM + + The founding of the British Museum, p. 4--Purchase of Sir Hans Sloane's + collection of curios by the English government, p. 4--Collection of + curios and library located in Montague Mansion, p. 5--Acquisition of + the collection of Sir William Hamilton, p. 5--Capture of Egyptian + antiquities by the English, p. 5--Construction of the present museum + building, p. 6--The Mesopotamian department, p. 8--The Museum of Natural + History in South Kensington, p. 8--Novel features in the structure of + the building, p. 9--Arrangement of specimens to illustrate evolution, + protective coloring, etc., p.-- --Exhibits of stuffed specimens amid + their natural surroundings, p. 10--Interest taken by visitors in the + institution, p. 12. + + CHAPTER II--THE ROYAL SOCIETY OP LONDON FOR IMPROVING NATURAL KNOWLEDGE + + The Royal Society, p. 14--Weekly meetings of the society, p. 15--The tea + before the opening of the lecture, p. 15--Announcement of the beginning + of the lecture by bringing in the great mace, p. 16--The lecture-room + itself, p. 17--Comparison of the Royal Society and the Royal Academy + of Sciences at Berlin, p. 18--The library and reading-room, p. 19--The + busts of distinguished members, p. 20--Newton's telescope and Boyle's + air-pump, p. 21. + + CHAPTER III--THE ROYAL INSTITUTION AND LOW-TEMPERATURE RESEARCHES + + The founding of the Royal Institution, p. 29--Count Rumford, p. 30--His + plans for founding the Royal Institution, p. 32--Change in the spirit + of the enterprise after Rumford's death, p. 33--Attitude of the + earlier workers towards the question of heat as a form of motion, + p. 34--Experiments upon gases by Davy and Faraday, p. 35--Faraday's + experiments with low temperatures, p. 39--Other experiments to produce + lower temperature, p. 39--Professor De-war begins low-temperature + research, p. 39--His liquefaction of hydrogen, p. 43--Hampson's method + of producing low temperatures, p. 44--Dewar's invention of the vacuum + vessel, p. 53--Its use in retaining liquefied gases, p. 54--Changes in + physical properties of substances at excessively low temperatures, p. + 56--Magnetic phenomena at low temperatures, p. 56--Changes in the color + of substances at low temperatures, p. 57--Substances made luminous by + low temperatures, p. 58--Effect of low temperatures upon the strength of + materials, p. 59--Decrease of chemical activity at low temperatures, p. + 60--Olzewski's experiments with burning substances in liquid oxygen, + p. 61--Approach to the absolute zero made by liquefying hydrogen, p. + 69--Probable form of all matter at the absolute zero, p. 70--Uncertain + factors that enter into this determination, p. 71. + + CHAPTER IV--SOME PHYSICAL LABORATORIES AND PHYSICAL PROBLEMS + + Sir Norman Lockyer and Spectroscopic Studies of the Sun and Stars, p. + 73--Observations made at South Kensington by Sir Norman and his staff, + p. 74--His theories as to the influence of sun-spots and terrestrial + weather, p. 75--Spectroscopic studies of sun-spots, p. 76--Studies of + the so-called reverse lines of the spectrum, p. 78--Discovery of the new + star in the constellation of Perseus, p. 80--Spectroscopic studies + of the new star, p. 81--Professor Ramsay and the new gases, p. + 82--University College in London, p. 83--Professor Ramsay's laboratory + and its equipment, p. 84--The discovery of argon, p. 86--Professor + Ramsay's work on krypton, neon, and zenon, p. 87--Discoveries of new + constituents of the atmosphere, p. 88--Interesting questions raised + by these discoveries, p. 89--Professor J. J. Thomson and the nature + of electricity, p. 92--Study of gases in relation to the conduction + of electricity, p. 93--Electricity regarded as a form of matter, p. + 97--Radio-activity, p. 97--The nature of emanations from radio-active + bodies, p. 10a--The source of energy of radioactivity, p. + 106--Radio-activity and the structure of the atom, p. 108--Effect of + radio-activity upon heat-giving life of the sun and the earth, p. 111. + + CHAPTER V--THE MARINE BIOLOGICAL LABORATORY + + The aquarium, p. 113--The arrangement of the tanks and exhibits, p. + 114--The submarine effect of this arrangement, p. 115--Appearance of the + submarine dwellers in their natural surroundings, p. 116--The eels and + cuttle-fishes, p. 116--The octopuses, p. 117--The technical department + of the laboratory, p. 119--The work of Dr. Anton Dohrn, founder of the + laboratory, p. 121--The associates of Dr. Dohrn, p. 122--The collecting + of surface specimens, p. 123--Collecting specimens by dredging, p. + 124--Fauna of the Bay of Naples, p. 124--Abundance of the material for + biological study, p. 125--Advantages offered by marine specimens for + biological study, p. 126--Method of preserving jelly-fish and similar + fragile creatures, p. 127--Uses made of the specimens in scientific + study, p. 128--Different nationalities represented among the workers at + the laboratory, p. 130--Methods of investigation, p. 131--Dr. Diesch's + studies of heredity at the laboratory, p. 131--Other subjects under + scientific investigation, p. 132--The study of chromosomes, p. + 133--Professor Weismann's theory of heredity based on these studies, + p. 33--Experiments in the division of egg-cells, p. 134--Experiments + tending to refute Weismann's theory, p. 136--Dr. Dohrn*s theory of + the type of the invertebrate ancestor, p. 137--Publications of the + laboratory, p. 139--Meetings of the investigators at Signor Bifulco's, + p. 141--Marine laboratories of other countries, p. 142. + + CHAPTER VI--ERNST HAECKEL AND THE NEW ZOOLOGY + + The "dream city" of Jena, p. 145--The old market-place, p. 147--The + old lecture-halls of the university, p. 148--Ernst Haeckel, p. 151--His + discoveries of numerous species of radiolarians, p. 153--The part played + in evolution by radiolarians, p. 156--Haeckel's work on morphology, + and its aid to Darwinian philosophy, p. 156--Freedom of thought and + expression in the University of Jena, p. 157--Haeckel's laboratory, p. + 160--His method of working, p. 161--His methods of teaching, p. 164--The + import of the study of zoology, p. 166--Its bearing upon evolution, p. + 168--The present status of Haeckel's genealogical tree regarding the + ancestry of man, p. 171--Dubois's discovery of the skull of the ape-man + of Java, p. 173--Its close resemblance to the skull of the ape, p. + 173--Man's line of descent clearly traced by Haeckel, p. 175--The + "missing link" no longer missing, p. 176. + + CHAPTER VII--SOME MEDICAL LABORATORIES AND MEDICAL PROBLEMS + + The Boulevard Pasteur, p. 179--The Pasteur Institute, p. 180--The tomb + of Pasteur within the walls, p. 181--Aims and objects of the Pasteur + Institute, p. 182--Antirabic treatment given, p. 183--Methods of + teaching in the institute, p. 185--The director of the institute and his + associates, p. 185--The Virchow Institute of Pathology, p. 186--Studies + of the causes of diseases, p. 187--Organic action and studies of + cellular activities, p. 188--The discoveries of Rudolph Virchow, p. + 188--His work in pathology, p. 189--Character of the man, his ways of + living and working, p. 189--His methods of lecturing and teaching, p. + 191--The Berlin Institute of Hygiene, p. 193--Work of Professor Koch + as carried on in the institute, p. 194--Work of his successors in the + institute, p. 195--Investigations in hygiene, p. 196--Investigations + of the functions of the human body in their relations to everyday + environment, p. 197--The Museum of Hygiene, p. 198--Studies in methods + of constructing sewerage systems in large cities, p. 199--Studies in + problems of ventilation, p. 200. + + CHAPTER VIII--SOME UNSOLVED SCIENTIFIC PROBLEMS + + The ever-shifting ground of scientific progress, p. 203--Solar and + telluric problems, p. 205--Mayer's explanation of the continued heat + of the sun, p. 206--Helmholtz's suggestion as to the explanation, p. + 207--The estimate of the heat-giving life of the sun by Lord Kelvin + and Professor Tait, p. 208--Lockyer's suggestion that the chemical + combination of elements might account for the sun's heat, p. + 209--Computations as to the age of the earth's crust, p. 210--Lord + Kelvin's computation of the rigidity of the telluric structure, p. + 211--Estimates of the future life of the earth, p. 212--Physical + problems, p. 213--Attempts to explain the power of gravitation, + p. 214--The theory of Le Sage, p. 214--Speculations based upon the + hypothesis of the vortex atom, p. 216--Lord Kelvin's estimate of the + vortex theory, p. 217--Attempted explanation of the affinity of + atoms, p. 217--Solubility, as explained by Ostwald and Mendeleef, p. + 218--Professor Van 't Hoof's studies of the space relations of atoms, p. + 219--Life problems, p. 220--Question as to living forms on other worlds + besides our own, p. 21 x--The question of the "spontaneous generation" + of living protoplasm, p. 222--The question of the evolution from + non-vital to vital matter, p. 223--The possibility of producing organic + matter from inorganic in the laboratory, p. 224--Questions as to + the structure of the cell, p. 225--Van Beneden's discovery of the + centrosome, p. 226--Some problems of anthropology, p. 227. + + CHAPTER IX--RETROSPECT AND PROSPECT + + The scientific attitude of mind, p. 2 30--Natural versus supernatural, + p. 233--Inductive versus deductive reasoning, p. 235--Logical induction + versus hasty generalization, p. 239--The future of Darwinism, p. 241. + + APPENDIX + + A LIST OF SOURCES + + + + +A HISTORY OF SCIENCE--BOOK V + + + + +ASPECTS OF RECENT SCIENCE + +STUDENTS of the classics will recall that the old Roman historians were +accustomed to detail the events of the remote past in what they were +pleased to call annals, and to elaborate contemporary events into +so-called histories. Actuated perhaps by the same motives, though with +no conscious thought of imitation, I have been led to conclude this +history of the development of natural science with a few chapters +somewhat different in scope and in manner from the ones that have gone +before. + +These chapters have to do largely with recent conditions. Now and again, +to be sure, they hark back into the past, as when they tell of the +origin of such institutions as the British Museum, the Royal Society, +and the Royal Institution; or when the visitor in modern Jena imagines +himself transplanted into the Jena of the sixteenth century. But these +reminiscent moods are exceptional. Our chief concern is with strictly +contemporary events--with the deeds and personalities of scientific +investigators who are still in the full exercise of their varied powers. +I had thought that such outlines of the methods of contemporary workers, +such glimpses of the personalities of living celebrities, might form a +fitting conclusion to this record of progress. There is a stimulus in +contact with great men at first hand that is scarcely to be gained in +like degree in any other way. So I have thought that those who have not +been privileged to visit the great teachers in person might like to +meet some of them at second hand. I can only hope that something of +the enthusiasm which I have gained from contact with these men may make +itself felt in the succeeding pages. + +It will be observed that these studies of contemporary workers are +supplemented with a chapter in which a hurried review is taken of the +field of cosmical, of physical, and of biological science, with +reference to a few of the problems that are still unsolved. As we have +noted the clearing up of mystery after mystery in the past, it may be +worth our while in conclusion thus to consider the hordes of mysteries +which the investigators of our own age are passing on to their +successors. For the unsolved problems of to-day beckon to the alluring +fields of to-morrow. + + + + +I. THE BRITISH MUSEUM + +IN the year 1753 a remarkable lottery drawing took place in London. +It was authorized, through Parliament, by "his gracious Majesty" King +George the Second. Such notables as the archbishop of Canterbury and the +lord chancellor of the realm took official interest in its success. It +was advertised far and wide--as advertising went in those days--in the +_Gazette_, and it found a host of subscribers. Of the fifty thousand +tickets--each costing three pounds--more than four thousand were to +be of the class which the act of Parliament naively describes as +"fortunate tickets." The prizes aggregated a hundred thousand pounds. + +To be sure, state lotteries were no unique feature in the England of +that day. They formed as common a method of raising revenue in the +island realm of King George II. as they still do in the alleged +continental portion of his realm, France, and in the land of his +nativity, Germany. Indeed, the particular lottery in question was to +be officered by the standing committee on lotteries, whose official +business was to "secure two and a half million pounds for his Majesty" +by this means. But the great lottery of 1754 had interest far beyond the +common run, for it aimed to meet a national need of an anomalous kind--a +purely intellectual need. The money which it was expected to bring was +to be used to purchase some collections of curiosities and of books that +had been offered the government, and to provide for their future care +and disposal as a public trust for the benefit and use of the people. +The lottery brought the desired money as a matter of course, for the +"fool's tax" is the one form of revenue that is paid without stint and +without grumbling. Almost fifty thousand pounds remained in the hands +of the archbishop of Canterbury and his fellow-trustees after the prizes +were paid. And with this sum the institution was founded which has been +increasingly famous ever since as the British Museum. + +The idea which had this splendid result had originated with Sir Hans +Sloane, baronet, a highly respected practising physician of Chelsea, +who had accumulated a great store of curios, and who desired to see the +collection kept intact and made useful to the public after his death. +Dying in 1753, this gentleman had directed in his will that the +collection should be offered to the government for the sum of twenty +thousand pounds; it had cost him fifty thousand pounds. The government +promptly accepted the offer--as why should it not, since it had at hand +so easy a means of raising the necessary money? It was determined to +supplement the collection with a library of rare books, for which +ten thousand pounds was to be paid to the Right Honorable Henrietta +Cavendish Holies, Countess of Oxford and Countess Mortimer, Relict of +Edward, Earl of Oxford and Earl Mortimer, and the Most Noble Margaret +Cavendish, Duchess of Portland, their only daughter. + +The purchases were made and joined with the Cottonian library, which +was already in hand. A home was found for the joint collection, along +with some minor ones, in Montague Mansion, on Great Russell Street, and +the British Museum came into being. Viewed retrospectively, it seems +a small affair; but it was a noble collection for its day; indeed, +the Sloane collection of birds and mammals had been the finest private +natural history collection in existence. But, oddly enough, the weak +feature of the museum at first was exactly that feature which has been +its strongest element in more recent years--namely, the department of +antiquities. This department was augmented from time to time, notably by +the acquisition of the treasures of Sir William Hamilton in 1773; but it +was not till the beginning of the nineteenth century that the windfall +came which laid the foundation for the future incomparable greatness of +the museum as a repository of archaeological treasures. + +In that memorable year the British defeated the French at Alexandria, +and received as a part of the conqueror's spoils a collection of +Egyptian antiquities which the savants of Napoleon's expedition had +gathered and carefully packed, and even shipped preparatory to sending +them to the Louvre. The feelings of these savants may readily be +imagined when, through this sad prank of war, their invaluable treasures +were envoyed, not to their beloved France, but to the land of their +dearest enemies, there to be turned over to the trustees of the British +Museum. + +The museum authorities were not slow to appreciate the value of the +treasures that had thus fallen into their hands, yet for the moment +it proved to them something of a white elephant. Montague Mansion was +already crowded; moreover, its floors had never been intended to hold +such heavy objects, so it became imperatively necessary to provide new +quarters for the collection. This was done in 1807 by the erection of +a new building on the old site. But the trustees of that day failed to +gauge properly the new impulse to growth that had come to the museum +with the Egyptian antiquities, for the new building was neither in +itself sufficient for the needs of the immediate future nor yet +so planned as to be susceptible of enlargement with reasonable +architectural effect. The mistakes were soon apparent, but, despite +various tentatives and "meditatings," fourteen years elapsed before +the present magnificent building was planned. The construction, wing by +wing, began in 1823, but it was not until 1846 that the last vestige +of the old museum buildings had vanished, and in their place, spreading +clear across the spacious site, stood a structure really worthy of the +splendid collection for which it was designed. + +But no one who sees this building to-day would suspect its relative +youth. Half a century of London air can rival a cycle of Greece or Italy +in weathering effect, and the fine building of the British Museum +frowns out at the beholder to-day as grimy and ancient-seeming as if +its massive columns dated in fact from the old Grecian days which they +recall. Regardless of age, however, it is one of the finest and most +massive specimens of Ionic architecture in existence. Forty-four massive +columns, in double tiers, form its frontal colonnade, jutting forward +in a wing at either end. The flight of steps leading to the central +entrance is in itself one hundred and twenty-five feet in extent; the +front as a whole covers three hundred and seventy feet. Capping the +portico is a sculptured tympanum by Sir Richard Westmacott, representing +the "Progress of Civilization" not unworthily. As a whole, the building +is one of the few in London that are worth visiting for an inspection of +their exterior alone. It seems admirably designed to be, as it is, the +repository of one of the finest collections of Oriental and classical +antiquities in the world. + +There is an air of repose about the _ensemble_ that is in itself +suggestive of the Orient; and the illusion is helped out by the pigeons +that flock everywhere undisturbed about the approaches to the building, +fluttering to be fed from the hand of some recognized friend, and +scarcely evading the feet of the casual wayfarer. With this scene before +him, if one will close his ears to the hum of the great city at his +back he can readily imagine himself on classical soil, and, dreaming of +Greece and Italy, he will enter the door quite prepared to find himself +in the midst of antique marbles and the atmosphere of by-gone ages. + +I have already pointed out that the turning-point in the history of +the British Museum came just at the beginning of the century, with the +acquisition of the Egyptian antiquities. With this the institution threw +off its swaddling-clothes. Hitherto it had been largely a museum of +natural history; in future, without neglecting this department, it +was to become equally important as a museum of archaeology. The Elgin +marbles, including the wonderful Parthenon frieze, confirmed this +character, and it was given the final touch by the reception, about +the middle of the century, of the magnificent Assyrian collection just +exhumed at the seat of old Nineveh by Mr. (afterwards Sir Henry) Layard. +Since then these collections, with additions of similar character, have +formed by far the most important feature of the British Museum. But in +the mean time archaeology has become a science. + +Within recent years the natural history collection has been removed _in +toto_ from the old building to a new site far out in South Kensington, +and the casual visitor is likely to think of it as a separate +institution. The building which it occupies is very modern in appearance +as in fact. It is a large and unquestionably striking structure, and one +that gives opportunity for very radical difference of opinion as to its +architectural beauty. By some it is much admired; by others it is almost +equally scoffed at. Certain it is that it will hardly bear comparison +with the parent building in Great Russell Street. + +Interiorly, the building of the natural history museum is admirably +adapted for its purpose. Its galleries are for the most part well +lighted, and the main central hall is particularly well adapted for +an exhibition of specimens, to which I shall refer more at length in +a moment. For the rest there is no striking departure from the +conventional. Perhaps it is not desired that there should be, since long +experience seems to have settled fairly well the problem of greatest +economy of space, combined with best lighting facilities, which always +confronts the architect in founding a natural history museum. + +There is, however, one striking novel feature in connection with the +structure of the natural history museum at Kensington which must not +be overlooked. This is the quite unprecedented use of terra-cotta +ornamentation. Without there is a striking display of half-decorative +and half-realistic forms; while within the walls and pillars everywhere +are covered with terracotta bas-reliefs representing the various forms +of life appropriate to the particular department of the museum which +they ornament. This very excellent feature might well be copied +elsewhere, and doubtless will be from time to time. + +As to the exhibits proper within the museum, it may be stated in a word +that they cover the entire range of the faunas and floras of the +globe in a variety and abundance of specimens that are hardly excelled +anywhere, and only duplicated by one or two other collections in Europe +and two or three in America. + +It would be but a reiteration of what the catalogues of all large +collections exhibit were one to enumerate the various forms here shown, +but there are two or three exhibits in this museum which are more novel +and which deserve special mention. One of these is to be found in a set +of cases in the main central hall. Here are exhibited, in a delightfully +popular form, some of the lessons that the evolutionist has taught us +during the last half-century. Appropriately enough, a fine marble statue +of Darwin, whose work is the fountain-head of all these lessons, is +placed on the stairway just beyond, as if to view with approval this +beautiful exemplification of his work. + +One of these cases illustrates the variations of animals under +domestication, the particular specimens selected being chiefly the +familiar pigeon, in its various forms, and the jungle-fowl with its +multiform domesticated descendants. + +Another case illustrates very strikingly the subject of protective +coloration of animals. Two companion cases are shown, each occupied by +specimens of the same species of birds and animals--in one case in their +summer plumage and pelage and in the other clad in the garb of winter. +The surroundings in the case have, of course, been carefully prepared +to represent the true environments of the creatures at the appropriate +seasons. The particular birds and animals exhibited are the +willow-grouse, the weasel, and a large species of hare. All of these, +in their summer garb, have a brown color, which harmonizes marvellously +with their surroundings, while in winter they are pure white, to match +the snow that for some months covers the ground in their habitat. + +The other cases of this interesting exhibit show a large variety of +birds and animals under conditions of somewhat abnormal variation, in +the one case of albinism and the other of melanism. These cases are, +for the casual visitor, perhaps the most striking of all, although, of +course, they teach no such comprehensive lessons as the other exhibits +just referred to. + +The second of the novel exhibits of the museum to which I wish to refer +is to be found in a series of alcoves close beside the central cases in +the main hallway. + +Each of these alcoves is devoted to a class of animals--one to mammals, +one to birds, one to fishes, and so on. In each case very beautiful sets +of specimens have been prepared, illustrating the anatomy and physiology +of the group of animals in question. Here one may see, for example, in +the alcove devoted to birds, specimens showing not only details of +the skeleton and muscular system, but the more striking examples of +variation of form of such members as the bill, legs, wings, and tails. +Here are preparations also illustrating, very strikingly, the vocal +apparatus of birds. Here, again, are finely prepared wings, in which +the various sets of feathers have been outlined with different-colored +pigments, so that the student can name them at a glance. In fact, every +essential feature of the anatomy of the bird may be studied here as in +no other collection that I know of. And the same is true of each of the +other grand divisions of the animal kingdom. This exhibit alone gives an +opportunity for the student of natural history that is invaluable. It is +quite clear to any one who has seen it that every natural history museum +must prepare a similar educational exhibit before it can claim to do +full justice to its patrons. + +A third feature that cannot be overlooked is shown in the numerous cases +of stuffed birds, in which the specimens are exhibited, not merely +by themselves on conventional perches, but amid natural surroundings, +usually associated with their nests and eggs or young. These exhibits +have high artistic value in addition to their striking scientific worth. +They teach ornithology as it should be taught, giving such clews to +the recognition of birds in the fields as are not at all to be found in +ordinary collections of stuffed specimens. This feature of the museum +has, to be sure, been imitated in the American Museum of Natural History +in New York, but the South Kensington Museum was the first in the field +and is still the leader. + +A few words should be added as to the use made by the public of the +treasures offered for their free inspection by the British Museum. I +shall attempt nothing further than a few data regarding actual visits to +the museum. In the year 1899 the total number of such visits +aggregated 663,724; in 1900 the figures rise to 689,249--well towards +three-quarters of a million. The number of visits is smallest in the +winter months, but mounts rapidly in April and May; it recedes slightly +for June and July, and then comes forward to full tide in August, during +which month more than ninety-five thousand people visited the museum +in 1901, the largest attendance in a single day being more than nine +thousand. August, of course, is the month of tourists--particularly of +tourists from America--but it is interesting and suggestive to note +that it is not the tourist alone who visits the British Museum, for the +flood-tide days of attendance are always the Bank holidays, including +Christmas boxing-day and Easter Monday, when the working-people turn out +_en masse_. On these days the number of visits sometimes mounts above +ten thousand. + +All this, it will be understood, refers exclusively to the main building +of the museum on Great Russell Street. But, meantime, out in Kensington, +at the natural history museum, more than half a million visits each year +are also made. In the aggregate, then, about a million and a quarter of +visits are paid to the British Museum yearly, and though the bulk of the +visitors may be mere sight-seers, yet even these must carry away many +ideas of value, and it hardly requires argument to show that, as a +whole, the educational influence of the British Museum must be enormous. +Of its more direct stimulus to scientific work through the trained +experts connected with the institution I shall perhaps speak in another +connection. + + + + +II. THE ROYAL SOCIETY OF LONDON FOR IMPROVING NATURAL KNOWLEDGE + + +A SESSION OF THE SOCIETY + +THERE is one scientific institution in London more venerable and more +famous even than the British Museum. This, of course, is the Royal +Society, a world-famous body, whose charter dates from 1662, but whose +actual sessions began at Gresham College some twenty years earlier. One +can best gain a present-day idea of this famous institution by attending +one of its weekly meetings in Burlington House, Piccadilly--a great, +castle-like structure, which serves also as the abode of the Royal +Chemical Society and the Royal Academy of Arts. The formality of an +invitation from a fellow is required, but this is easily secured by any +scientific visitor who may desire to attend the meeting. The +programme of the meeting each week appears in that other great British +institution, the _Times_, on Tuesdays. + +The weekly meeting itself is held on Thursday afternoon at half-past +four. As one enters the door leading off the great court of Burlington +House a liveried attendant motions one to the rack where great-coat +and hat may be left, and without further ceremony one steps into the +reception-room unannounced. It is a middle-sized, almost square room, +pillared and formal in itself, and almost without furniture, save for +a long temporary table on one side, over which cups of tea are being +handed out to the guests, who cluster there to receive it, and then +scatter about the room to sip it at their leisure. We had come to hear +a lecture and had expected to be ushered into an auditorium; but we had +quite forgotten that this is the hour when all England takes its tea, +the _elite_ of the scientific world, seemingly, quite as much as the +devotees of another kind of society. Indeed, had we come unawares into +this room we should never have suspected that we had about us other than +an ordinary group of cultured people gathered at a conventional +"tea," except, indeed, that suspicion might be aroused by the great +preponderance of men--there being only three or four women present--and +by the fact that here and there a guest appears in unconventional +dress--a short coat or even a velvet working-jacket. For the rest +there is the same gathering into clusters of three or four, the same +inarticulate clatter of many voices that mark the most commonplace of +gatherings. + +But if one will withdraw to an inoffensive corner and take a critical +view of the assembly, he will presently discover that many of the faces +are familiar to him, although he supposed himself to be quite among +strangers. The tall figure, with the beautiful, kindly face set in +white hair and beard, has surely sat for the familiar portrait of Alfred +Russel Wallace. This short, thick-set, robust, business-like figure is +that of Sir Norman Lockyer. Yonder frail-seeming scholar, with white +beard, is surely Professor Crookes. And this other scholar, with tall, +rather angular frame and most kindly gleam of eye, is Sir Michael +Foster; and there beyond is the large-seeming though not tall figure, +and the round, rosy, youthful-seeming, beautifully benevolent face of +Lord Lister. "What! a real lord there?" said a little American girl to +whom I enumerated the company after my first visit to the Royal Society. +"Then how did he act? Was he very proud and haughty, as if he could not +speak to other people?" And I was happy to be able to reply that though +Lord Lister, perhaps of all men living, would be most excusable did he +carry in his manner the sense of his achievements and honors, yet in +point of fact no man could conceivably be more free from any apparent +self-consciousness. As one watches him now he is seen to pass from group +to group with cordial hand-shake and pleasant word, clearly the most +affable of men, lord though he be, and president of the Royal Society, +and foremost scientist of his time. + +Presently an attendant passed through the tearoom bearing a tremendous +silver mace, perhaps five feet long, surmounted by a massive crown and +cross, and looking like nothing so much as a "gigantic war-club." +This is the mace which, when deposited on the president's desk in the +lecture-room beyond, will signify that the society is in session. "It is +the veritable mace," some one whispers at your elbow, "concerning which +Cromwell gave his classical command to 'Remove that bauble.'" But since +the mace was not made until 1663, some five years after Cromwell's +death, this account may lack scientific accuracy. Be that as it may, +this mace has held its own far more steadily than the fame of its +alleged detractor, and its transportation through the tea-room is the +only manner of announcement that the lecture is about to open in the +hall beyond. Indeed, so inconspicuous is the proceeding, and so quietly +do the members that choose to attend pass into the lecture-hall, leaving +perhaps half the company engaged as before, that the "stranger "--as +the non-member is here officially designated--might very readily fail +to understand that the seance proper had begun. In any event, he cannot +enter until permission has been formally voted by the society. + +When he is allowed to enter he finds the meeting-room little different +from the one he has left, except that it is provided with a sort of +throne on a raised platform at one end and with cushioned benches for +seats. On the throne, if one may so term it, sits Lord Lister, scarcely +more than his head showing above what seems to be a great velvet cushion +which surmounts his desk, at the base of which, in full view of the +society, rests the mace, fixing the eye of the "stranger," as it is +alleged to have fixed that of Cromwell aforetime, with a peculiar +fascination. On a lower plane than the president, at his right and left, +sit Sir Michael Foster and Professor Arthur William Rucker, the two +permanent secretaries. At Sir Michael's right, and one stage nearer the +audience, stands the lecturer, on the raised platform and behind the +desk which extends clear across the front of the room. As it chances, +the lecturer this afternoon is Professor Ehrlich, of Berlin and +Frankfort-on-the-Main, who has been invited to deliver the Croonian +lecture. He is speaking in German, and hence most of the fellows are +assisting their ears by following the lecture in a printed translation, +copies of which, in proof, were to be secured at the door. + +The subject of the lecture is "Artificial Immunization from Disease." +It is clear that the reader is followed with interested attention, which +now and again gives rise to a subdued shuffle of applause. + +The fact that the lecturer is speaking German serves perhaps to suggest +even more vividly than might otherwise occur to one the contrast between +this meeting and a meeting of the corresponding German society--the +Royal Academy of Sciences at Berlin. Each is held in an old building +of palatial cast and dimensions, of which Burlington House, here +in Piccadilly, is much the older--dating from 1664--although its +steam-heating and electric-lighting apparatus, when contrasted with the +tile stoves and candles of the other, would not suggest this. For the +rest, the rooms are not very dissimilar in general appearance, except +for the platform and throne. But there the members of the society are +shut off from the audience both by the physical barrier of the table and +by the striking effect of their appearance in full dress, while here the +fellows chiefly compose the audience, there being only a small company +of "strangers" present, and these in no way to be distinguished by dress +or location from the fellows themselves. It may be added that the custom +of the French Academy of Sciences is intermediate between these two. +There the visitors occupy seats apart, at the side of the beautiful +hall, the main floor being reserved for members. But the members +themselves are not otherwise distinguishable, and they come and go and +converse together even during the reading of a paper almost as if this +were a mere social gathering. As it is thus the least formal, the +French meeting is also by far the most democratic of great scientific +gatherings. Its doors are open to whoever may choose to enter. The +number who avail themselves of this privilege is not large, but it +includes, on occasions, men of varied social status and of diverse races +and colors--none of whom, so far as I could ever discern, attracts the +slightest attention. + +At the German meeting, again, absolute silence reigns. No one thinks +of leaving during the session, and to make any sound above a sigh would +seem almost a sacrilege. But at the Royal Society an occasional auditor +goes or comes, there are repeated audible signs of appreciation of the +speaker's words, and at the close of the discourse there is vigorous +and prolonged applause. There is also a debate, of the usual character, +announced by the president, in which "strangers" are invited to +participate, and to which the lecturer finally responds with a brief +_Nachwort_, all of which is quite anomalous from the German or French +stand-points. After that, however, the meeting is declared adjourned +with as little formality in one case as in the others, and the fellows +file leisurely out, while the attendant speedily removes the mace, in +official token that the seance of the Royal Society is over. + + +THE LIBRARY AND READING-ROOM + +But the "stranger" must not leave the building without mounting to the +upper floor for an inspection of the library and reading-room. The rooms +below were rather bare and inornate, contrasting unfavorably with the +elegant meeting-room of the French institute. But this library makes +full amends for anything that the other rooms may lack. It is one of the +most charming--"enchanting" is the word that the Princess Christian is +said to have used when she visited it recently--and perhaps quite the +most inspiring room to be found in all London. It is not very large as +library rooms go, but high, and with a balcony supported by Corinthian +columns. The alcoves below are conventional enough, and the high +tables down the centre, strewn with scientific periodicals in engaging +disorder, are equally conventional. But the color-scheme of the +decorations--sage-green and tawny--is harmonious and pleasing, and the +effect of the whole is most reposeful and altogether delightful. + +Chief distinction is given the room, however, by a row of busts on +either side and by certain pieces of apparatus on the centre tables. + +The busts, as will readily be surmised, are portraits of distinguished +fellows of the Royal Society. There is, however, one exception to this, +for one bust is that of a woman--Mary Somerville, translator of the +_Mecanique Celeste_, and perhaps the most popular of the scientific +writers of her time. It is almost superfluous to state that the row of +busts begins with that of Newton. The place of honor opposite is held by +that of Faraday. Encircling the room to join these two one sees, among +others, the familiar visages of Dr. Gilbert; of Sir Joseph Banks, the +famous surgeon of the early nineteenth century, who had the honor of +being the only man that ever held the presidential chair of the +Royal Society longer than it was held by Newton; of James Watts, of +"steam-engine" fame; of Sabine, the astronomer, also a president of +the society; and of Dr. Falconer and Sir Charles Lyell, the famous +geologists. + +There are numerous other busts in other rooms, some of them stowed away +in nooks and crannies, and the list of those selected for the library +does not, perhaps, suggest that this is the room of honor, unless, +indeed, the presence of Newton and Faraday gives it that stamp. But in +the presence of the images of these two, and of Lyell, to go no farther, +one feels a certain sacredness in the surroundings. + +If this is true of the mere marble images, what shall we say of the +emblems on the centre table? That little tubular affair, mounted on a +globe, the whole cased in a glass frame perhaps two feet high, is the +first reflecting telescope ever made, and it was shaped by the hand of +Isaac Newton. The brass mechanism at the end of the next table is the +perfected air-pump of Robert Boyle, Newton's contemporary, one of the +founders of the Royal Society and one of the most acute scientific minds +of any time. And here between these two mementos is a higher apparatus, +with crank and wheel and a large glass bulb that make it conspicuous. +This is the electrical machine of Joseph Priestley. There are other +mementos of Newton--a stone graven with a sun-dial, which he carved as +a boy, on the paternal manor-house; a chair, said to have been his, +guarded here by a silk cord against profanation; bits of the famous +apple-tree which, as tradition will have it, aided so tangibly in +the greatest of discoveries; and the manuscript of the _Principia_ +itself--done by the hand of an amanuensis, to be sure, but with +interlinear corrections in the small, clear script of the master-hand +itself. Here, too, is the famous death-mask, so much more interesting +than any sculptured portrait, and differing so strangely in its +broad-based nose and full, firm mouth from the over-refined lineaments +of the sculptured bust close at hand. In a room not far away, to reach +which one passes a score or two of portraits and as many busts of +celebrities--including, by-the-bye, both bust and portrait of Benjamin +Franklin--one finds a cabinet containing other mementos similar to those +on the library tables. Here is the first model of Davy's safety-lamp; +there a chronometer which aided Cook in his famous voyage round the +world. This is Wollaston's celebrated "Thimble Battery." It will slip +readily into the pocket, yet he jestingly showed it to a visitor as +"his entire laboratory." That is a model of the double-decked boat made +by Sir William Petty, and there beyond is a specimen of almost, if not +quite, the first radiometer devised by Sir William Crookes. + +As one stands in the presence of all these priceless relics, so vividly +do the traditions of more than two centuries of science come to mind +that one seems almost to have lived through them. One recalls, as if it +were a personal recollection, the founding of the Royal Society itself +in 1662, and the extraordinary scenes which the society witnessed during +the years of its adolescence. + +As one views the mementos of Boyle and Newton, one seems to be living in +the close of the seventeenth century. It is a troublous time in England. +Revolution has followed revolution. Commonwealth has supplanted monarchy +and monarchy commonwealth. At last the "glorious revolution" of 1688 has +placed a secure monarch on the throne. But now one external war follows +another, and the new king, William of Orange, is leading the "Grand +Alliance" against the French despot Louis XIV. There is war everywhere +in Europe, and the treaty of Ryswick, in 1697, is but the preparation +for the war of the Spanish Alliance, which will usher in the new +century. But amid all this political turmoil the march of scientific +discovery has gone serenely on; or, if not serenely, then steadily, and +perhaps as serenely as could be hoped. Boyle has discovered the law of +the elasticity of gases and a host of minor things. Robert Hooke is +on the track of many marvels. But all else pales before the fact that +Newton has just given to the world his marvellous law of gravitation, +which has been published, with authority of the Royal Society, through +the financial aid of Halley. The brilliant but erratic Hooke lias +contested the priority of discovery and strenuously claimed a share in +it. Halley eventually urges Newton to consider Hooke's claim in some of +the details, and Newton yields to the extent of admitting that the +great fact of gravitational force varying inversely as the square of +the distance had been independently discovered by Hooke; but he includes +also Halley himself and Sir Christopher Wren, along with Hooke, +as equally independent discoverers of the same principle. To the +twentieth-century consciousness it seems odd to hear Wren thus named as +a scientific discoverer; but in truth the builder of St. Paul's began +life as a professor of astronomy at Gresham College, and was the +immediate predecessor of Newton himself in the presidential chair of the +Royal Society. Now, at the very close of the seventeenth century, Boyle +is recently dead, but Hooke, Wren, Halley, and Newton still survive: +some of them are scarcely past their prime. It is a wonderful galaxy of +stars of the first magnitude, and even should no other such names come +in after-time, England's place among the scientific constellations is +secure. + +But now as we turn to the souvenirs of Cooke and Wollaston and Davy +the scene shifts by a hundred years. We are standing now in the closing +epoch of the eighteenth century. These again are troublous times. The +great new colony in the West has just broken off from the parent swarm. +Now all Europe is in turmoil. The French war-cloud casts its ominous +shadow everywhere. Even in England mutterings of the French Revolution +are not without an echo. The spirit of war is in the air. And yet, as +before, the spirit of science also is in the air. The strain of the +political relations does not prevent a perpetual exchange of courtesy +between scientific men and scientific bodies of various nations. Davy's +dictum that "science knows no country" is perpetually exemplified in +practice. And at the Royal Society, to match the great figures that were +upon the scene a century before, there are such men as the eccentric +Cavendish, the profound Wollaston, the marvellously versatile Priestley, +and the equally versatile and even keener-visioned Rumford. Here, too, +are Herschel, who is giving the world a marvellous insight into the +constitution of the universe; and Hutton, who for the first time gains a +clear view of the architecture of our earth's crust; and Jenner, who is +rescuing his fellow-men from the clutches of the most deadly of plagues; +to say nothing of such titanic striplings as Young and Davy, who are +just entering the scientific lists. With such a company about us we are +surely justified in feeling that the glory of England as a scientific +centre has not dimmed in these first hundred and thirty years of the +Royal Society's existence. + +And now, as we view the radiometer, the scene shifts by yet another +century, and we come out of cloud-land and into our own proper age. We +are at the close of the nineteenth century--no, I forget, we are fairly +entering upon the twentieth. Need I say that these again are troublous +times? Man still wages warfare on his fellow-man as he has done time +out of mind; as he will do--who shall say how long? But meantime, as +of yore, the men of science have kept steadily on their course. But +recently here at the Royal Society were seen the familiar figures of +Darwin and Lyell and Huxley and Tyndall. Nor need we shun any comparison +with the past while the present lists can show such names as Wallace, +Kelvin, Lister, Crookes, Foster, Evans, Rayleigh, Ramsay, and Lock-yer. +What revolutionary advances these names connote! How little did those +great men of the closing decades of the seventeenth and eighteenth +centuries know of the momentous truths of organic evolution for which +the names of Darwin and Wallace and Huxley stand! How little did +they know a century ago, despite Hutton's clear prevision, of these +marvellous slow revolutions through which, as Lyell taught us, the +earth's crust had been built up! Not even Jen-ner could foresee a +century ago the revolution in surgery which has been effected in our +generation through the teachings of Lister. + +And what did Rumford and Davy know of energy in its various +manifestations as compared with the knowledge of to-day, of Crookes +and Rayleigh and Ramsay and Kelvin? What would Joseph Priestley, the +discoverer of oxygen, and Cavendish, the discoverer of nitrogen, +think could they step into the laboratory of Professor Ramsay and see +test-tubes containing argon and helium and krypton and neon and zenon? +Could they more than vaguely understand the papers contributed in recent +years to the Royal Society, in which Professor Ramsay explains how these +new constituents of the atmosphere are obtained by experiments on liquid +air. "Here," says Professor Ramsay, in effect, in a late paper to the +society, "is the apparatus with which we liquefy hydrogen in order to +separate neon from helium by liquefying the former while the helium +still remains gaseous." Neon, helium, liquid air, liquid hydrogen--these +would seem strange terms to the men who on discovering oxygen and +nitrogen named them "dephlogisticated air" and "phlogisti-cated air" +respectively. + +Again, how elementary seems the teaching of Her-schel, wonderful though +it was in its day, when compared with our present knowledge of the +sidereal system as outlined in the theories of Sir Norman Lock-yer. +Herschel studied the sun-spots, for example, with assiduity, and even +suggested a possible connection between sun-spots and terrestrial +weather. So far, then, he would not be surprised on hearing the +announcement of Professor Lockyer's recent paper before the Royal +Society on the connection between sun-spots and the rainfall in India. +But when the paper goes on to speak of the actual chemical nature of the +sun-spots, as tested by a spectroscope; to tell of a "cool" stage when +the vapor of iron furnishes chief spectrum lines, and of a "hot" stage +when the iron has presumably been dissociated into unknown "proto-iron" +constituents--then indeed does it go far beyond the comprehension of the +keenest eighteenth-century intellect, though keeping within the range of +understanding of the mere scientific tyro of to-day. + +Or yet again, consider a recent paper contributed by Professor Lockyer +to the Royal Society, entitled "The New Star in Perseus: Preliminary +Note"--referring to the new star that flashed suddenly on the vision of +the terrestrial observers at more than first magnitude on February 22, +1901. This "star," the paper tells us, when studied by its spectrum, +is seen to be due to the impact of two swarms of meteors out in +space--swarms moving in different directions "with a differential +velocity of something like seven hundred miles a second." Every +astronomer of to-day understands how such a record is read from the +displacement of lines on the spectrum, as recorded on the photographic +negative. But imagine Sir William Herschel, roused from a century's +slumber, listening to this paper, which involves a subject of which he +was the first great master. "Ebulae," he might say; "yes, they were a +specialty of mine; but swarms of meteors--I know nothing of these. And +'spectroscopes,' 'photographs'--what, pray, are these? In my day there +were no such words or things as spectroscope and photograph; to my mind +these words convey no meaning." + +But why go farther? These imaginings suffice to point a moral that he +who runs may read. Of a truth the march of science still goes on as it +has gone on with steady tread throughout the long generations of the +Royal Society's existence. If the society had giants among its members +in the days of its childhood and adolescence, no less are there giants +still to keep up its fame in the time of its maturity. The place of +England among the scientific constellations is secure through tradition, +but not through tradition alone. + + + + +III. THE ROYAL INSTITUTION AND THE LOW-TEMPERATURE RESEARCHES + + +FOUNDATION AND FOUNDER + +"GEORGE THE THIRD, by the Grace of God King of Great Britain, France, +and Ireland, Defender of the Faith, etc., to all to whom these presents +shall come, greeting. Whereas several of our loving subjects are +desirous of forming a Public Institution for diffusing the knowledge and +facilitating the general introduction of Useful Mechanical Inventions +and Improvements; and for teaching, by Courses of Philosophical Lectures +and Experiments, the Application of Science to the Common Purposes of +Life, we do hereby give and grant"--multifarious things which need not +here be quoted. Such are the opening words of the charter with which, a +little more than a century ago, the Royal Institution of Great Britain +came into existence and received its legal christening. If one reads on +he finds that the things thus graciously "given and granted," despite +all the official verbiage, amount to nothing more than royal sanction +and approval, but doubtless that meant more in the way of assuring +popular approval than might at first glimpse appear. So, too, of the +list of earls, baronets, and the like, who appear as officers and +managers of the undertaking, and who are described in the charter as +"our right trusty and right well-beloved cousins," "our right trusty +and well-beloved counsellors," and so on, in the skilfully graduated +language of diplomacy. The institution that had the King for patron and +such notables for officers seemed assured a bright career from the very +beginning. In name and in personnel it had the flavor of aristocracy, +a flavor that never palls on British palate. And right well the +institution has fulfilled its promise, though in a far different way +from what its originator and founder anticipated. + +Its originator and founder, I say, and say advisedly; for, of course, +here, as always, there is one man who is the true heart and soul of the +movement, one name that stands, in truth, for the whole project, and to +which all the other names are mere appendages. You would never suspect +which name it is, in the present case, from a study of the charter, +for it appears well down the file of graded titles, after "cousins" and +"counsellors" have had their day, and is noted simply as "our trusty +and well-beloved Benjamin, Count of Rumford, of the Holy Roman Empire." +Little as there is to signalize it in the charter, this is the name of +the sole projector of the enterprise in its incipiency, of the +projector of every detail, of the writer of the charter itself even. The +establishment thus launched with royal title might with full propriety +have been called, as indeed it sometimes is called, the Rumford +Institution. + +The man who thus became the founder of this remarkable institution was +in many ways a most extraordinary person. He was an American by birth, +and if not the most remarkable of Americans, he surely was destined to +a more picturesque career than ever fell to the lot of any of his +countrymen of like eminence. Born on a Massachusetts farm, he was a +typical "down-east Yankee," with genius added to the usual shrewd, +inquiring mind and native resourcefulness. He was self-educated and +self-made in the fullest sense in which those terms can be applied. At +fourteen he was an unschooled grocer-lad--Benjamin Thompson by name--in +a little New England village; at forty he was a world-famous savant, +as facile with French, Italian, Spanish, and German as with his native +tongue; he had become vice-president and medallist of the Royal +Society, member of the Berlin National Academy of Science, of the French +Institute, of the American Academy of Science, and I know not what other +learned bodies; he had been knighted in Great Britain after serving +there as under-secretary of state and as an officer; and he had risen +in Bavaria to be more than half a king in power, with the titles, among +others, of privy councillor of state, and head of the war department, +lieutenant-general of the Bavarian armies, holder of the Polish order of +St. Stanislas and the Bavarian order of the White Eagle, ambassador to +England and to France, and, finally, count of the Holy Roman Empire. +Once, in a time of crisis, Rumford was actually left at the head of +a council of regency, in full charge of Bavarian affairs, the elector +having fled. The Yankee grocer-boy had become more than half a king. + +Never, perhaps, did a man of equal scientific attainments enjoy a +corresponding political power. Never was political power wielded more +justly by any man. + +For in the midst of all his political and military triumphs, Rumford +remained at heart to the very end the scientist and humanitarian. He +wielded power for the good of mankind; he was not merely a ruler but +a public educator. He taught the people of Bavaria economy and Yankee +thrift. He established kitchens for feeding the poor on a plan that was +adopted all over Europe; but, better yet, he created also workshops for +their employment and pleasure-gardens for their recreation. He actually +banished beggary from the principality. + +It was in the hope of doing in some measure for London what he had done +for Munich that this large-brained and large-hearted man was led to the +project of the Royal Institution. He first discussed his plans with a +committee of the Society for Alleviating the Condition of the Poor, for +it was the poor, the lower ranks of society, whom he wished chiefly to +benefit. But he knew that to accomplish his object, he must work through +the aristocratic channels; hence the name of the establishment and the +charter with its list of notables. The word institution was selected +by Rumford, after much deliberation, as, on the whole, the least +objectionable title for the establishment, as having a general +inclusiveness not possessed by such words as school or college. Yet in +effect it was a school which Rumford intended to found--a school for +the general diffusion of useful knowledge. There were to be classes +for mechanics, and workshops, kitchens, and model-rooms, where the +"application of science to the useful purposes of life" might be +directly and practically taught; also a laboratory for more technical +investigations, with a "professor" in charge, who should also deliver +popular lectures on science. Finally, there was to be a scientific +library. + +All these aims were put into effect almost from the beginning. The +necessary funds were supplied solely by popular subscription and by the +sale of lecture tickets (as all funds of the institution have been ever +since), and before the close of the year 1800 Rumford's dream had become +an actuality--as this practical man's dreams nearly always did. The new +machine did not move altogether without friction, of course, but on the +whole all went well for the first few years. The institution had found +a local habitation in a large building in Albemarle Street, the same +building which it still occupies, and for a time Rumford lived there and +gave the enterprise his undivided attention. He appointed the brilliant +young Humphry Davy to the professorship of chemistry, and the even +more wonderful Thomas Young to that of natural philosophy. He saw the +workshops and kitchens and model-rooms in running order--the entire +enterprise fully launched. Then other affairs, particularly an +attachment for a French lady, the widow of the famous chemist Lavoisier +(whom he subsequently married, to his sorrow), called him away from +England never to return. And the first chapter in the history of the +Royal Institution was finished. + + +METHOD AND RESULT + +Rumford, the humanitarian, gone, a curious change came over the spirit +of the enterprise he had founded. The aristocrats who at first were +merely ballast for the enterprise now made their influence felt. With +true British reserve, they announced their belief that the education of +the masses involved a dangerous political tendency. Hence the mechanics' +school was suspended and the workshops and kitchens abolished; in +a word, the chief ends for which the institution was founded were +annulled. The library and the lectures remained, to be sure, but they +were for the amusement of the rich, not for the betterment of the poor. +It was the West End that made a fad of the institution and a society +function of the lectures of Sydney Smith and of the charming youth Davy. +Thus the institution came to justify its aristocratic title and its +regal patronage; and the poor seemed quite forgotten. + +But indeed the institution itself was poor enough in these days, after +the first flush of enthusiasm died away, and it is but fair to remember +that without the support of its popular lectures its very existence +would have been threatened. Nor in any event are regrets much in order +over the possible might-have-beens of an institution whose laboratories +were the seat of the physical investigations of Thomas Young, through +which the wave theory of light first gained a footing, and of the +brilliant chemical researches of Davy, which practically founded the +science of electro-chemistry and gave the chemical world first knowledge +of a galaxy of hitherto unknown elements. Through the labors of +these men, and through the popular lecture-courses delivered at the +institution by such other notables of science as Wollaston, Dalton, and +Rum-ford, the enterprise had become world-famous before the close of the +first decade of its existence. + +From that day till this the character of the Royal Institution has +not greatly changed. The enterprise shifted around during its earliest +years, while it was gaining its place in the scheme of things; but once +that was found, like a true British institution it held its course with +an inertia that a mere century of time could not be expected to alter. +Rumford was the sole founder of the enterprise, but it was Davy who +gave it the final and definitive cast. He it was who established the +tradition that the Royal Institution was to be essentially a laboratory +for brilliant original investigations, the investigator to deliver +a yearly course of lectures, but to be otherwise untrammelled. It +occupied, and has continued to occupy, the anomalous position of a +school to which pupils are on no account admitted, and whose professors +teach nothing except by a brief course of lectures to which whoever +cares to pay the admission price may freely enter. + +But the marvellous results achieved at the Royal Institution have more +than justified the existence of so anomalous an enterprise. Superlatives +are always dangerous, but it may well be doubted whether there is +another single institution in the world where so many novel original +discoveries in physical science have been made as have been brought to +light in the laboratories of the building on Albemarle Street during +this first century of its occupancy; for practically all that is to +be credited to Thomas Young, Humphry Davy, Michael Faraday, and John +Tyndall, not to mention living investigators, is to be credited also to +the Royal Institution, whose professorial chairs these great men have +successively occupied. Davy spent here the best years of his youth +and prime. Faraday, his direct successor, came to the institution in a +subordinate capacity as a mere boy, and was the life of the institution +for half a century. Tyndall gave it forty years of service. What wonder, +then, that the Briton speaks of the institution as the "Pantheon of +Science"? + +If you visit the Royal Institution to-day you will find it in most +exterior respects not unlike what it presumably was a century ago. Its +long, stone front, dinged with age, with its somewhat Pantheon-like +colonnade, has an appearance of dignity rather than of striking +impressiveness. The main entrance, jutting full on the sidewalk, is at +the street level, and the glass door gives hospitable glimpses of the +interior. Entering, one finds himself in a main central hall, at the +foot of the main central staircase. The air of eminent respectability +so characteristic of the British institution is over all; likewise +the pervasive hush of British reserve. But you will not miss also the +atmosphere of sincere if uneffusive British courtesy. + +At your right, as you mount the stairway, is a large statue of Faraday; +on the wall right ahead is a bronze medallion of Tyndall, placed beneath +a large portrait of Davy. At the turn of the stairs is a marble bust of +Wollaston. Farther on, in hall and library, you will find other busts of +Faraday, other portraits of Davy; portraits of Faraday everywhere, +and various other busts of notables who have had connection with the +institution. You will be shown the lecture-hall where Davy, Faraday, +and Tyndall pronounced their marvellous discourses; the arrangement, the +seats, the cushions even if appearances speak truly, and certainly the +lecture-desk itself, unchanged within the century. You may see the crude +balance, clumsy indeed to modern eyes, with which Davy performed his +wonders. The names and the memories of three great men--Davy, +Faraday, and Tyndall--will be incessantly before you, and the least +impressionable person could not well escape a certain sense of +consecration of his surroundings. The hush that is over everything seems +but fitting. + +All that is as it should be. But there are other memories connected with +these surroundings which are not so tangibly presented to the senses. +For where, amid all these busts and portraits, is the image of that +other great man, the founder of the institution, the sole originator +of the enterprise which has made possible the aggregation of all +these names and these memories? Where are the remembrances of +that extraordinary man whom the original charter describes as "our +well-beloved Benjamin, Count of Rumford?" Well, you will find a portrait +of him, it is true, if you search far enough, hung high above a doorway +in a room with other portraits. But one finds it hard to escape the +feeling that there has been just a trifling miscarriage of justice in +the disposal. Doubtless there was no such intention, but the truth seems +to be that the glamour of the newer fame of Faraday has dazzled a little +the eyes of the rulers of the institution of the present generation. +But that, after all, is a small matter about which to quibble. There is +glory enough for all in the Royal Institution, and the disposal of busts +and portraits is unworthy to be mentioned in connection with the lasting +fame of the great men who are here in question. It would matter little +if there were no portrait at all of Rumford here, for all the world +knows that the Royal Institution itself is in effect his monument. His +name will always be linked in scientific annals with the names of Young, +Davy, Faraday, and Tyndall. And it is worthy such association, for +neither in native genius nor in realized accomplishments was Rumford +inferior to these successors. + + +FROM LIQUID CHLORINE TO LIQUID HYDROGEN + +Nor is it merely by mutual association with the history of the Royal +Institution that these great names are linked. There was a curious +and even more lasting bond between them in the character of their +scientific discoveries. They were all pioneers in the study of those +manifestations of molecular activity which we now, following Young +himself, term energy. Thus Rumford, Davy, and Young stood almost alone +among the prominent scientists of the world at the beginning of the +century in upholding the idea that heat is not a material substance--a +chemical element--but merely a manifestation of the activities of +particles of matter. Rumford's papers on this thesis, communicated to +the Royal Society, were almost the first widely heralded claims for this +then novel idea. Then Davy came forward in support of Rumford, with +his famous experiment of melting ice by friction. It was perhaps +this intellectual affinity that led Rumford to select Davy for +the professorship at the Royal Institution, and thus in a sense to +predetermine the character of the scientific work that should be +accomplished there--the impulse which Davy himself received from +Rum-ford being passed on to his pupil Faraday. There is, then, an +intangible but none the less potent web of association between the +scientific work of Rumford and some of the most important researches +that were conducted at the Royal Institution long years after his death; +and one is led to feel that it was not merely a coincidence that some +of Faraday's most important labors should have served to place on a firm +footing the thesis for which Rumford battled; and that Tyndall should +have been the first in his "beautiful book" called _Heat, a Mode of +Motion_, to give wide popular announcement to the fact that at last the +scientific world had accepted the proposition which Rumford had vainly +demonstrated three-quarters of a century before. + +This same web of association extends just as clearly to the most +important work which has been done at the Royal Institution in the +present generation, and which is still being prosecuted there--the +work, namely, of Professor James Dewar on the properties of matter at +excessively low temperatures. Indeed, this work is in the clearest sense +a direct continuation of researches which Davy and Faraday inaugurated +in 1823 and which Faraday continued in 1844. In the former year Faraday, +acting on a suggestion of Davy's, performed an experiment which resulted +in the production of a "clear yellow oil" which was presently proved to +be liquid chlorine. Now chlorine, in its pure state, had previously been +known (except in a forgotten experiment of Northmore's) only as a gas. +Its transmutation into liquid form was therefore regarded as a very +startling phenomenon. But the clew thus gained, other gases were +subjected to similar conditions by Davy, and particularly by Faraday, +with the result that several of them, including sulphurous, carbonic, +and hydrochloric acids were liquefied. The method employed, stated in +familiar terms, was the application of cold and of pressure. The results +went far towards justifying an extraordinary prediction made by that +extraordinary man, John Dalton, as long ago as 1801, to the effect that +by sufficient cooling and compressing all gases might be transformed +into liquids--a conclusion to which Dalton had vaulted, with the +sureness of supreme genius, from his famous studies of the properties of +aqueous vapor. + +Between Dalton's theoretical conclusion, however, and experimental +demonstration there was a tremendous gap, which the means at the +disposal of the scientific world in 1823 did not enable Davy and Faraday +more than partially to bridge. A long list of gases, including the +familiar oxygen, hydrogen, and nitrogen, resisted all their efforts +utterly--notwithstanding the facility with which hydrogen and oxygen +are liquefied when combined in the form of water-vapor, and the relative +ease with which nitrogen and hydrogen, combined to form ammonia, could +also be liquefied. Davy and Faraday were well satisfied of the truth of +Dalton's proposition, but they saw the futility of further efforts +to put it into effect until new means of producing, on the one hand, +greater pressures, and, on the other, more extreme degrees of cold, +should be practically available. So the experiments of 1823 were +abandoned. + +But in 1844 Faraday returned to them, armed now with new weapons, in the +way of better air-pumps and colder freezing mixtures, which the labors +of other workers, chiefly Thilorier, Mitchell, and Natterer, had made +available. With these new means, and without the application of any +principle other than the use of cold and pressure as before, Faraday now +succeeded in reducing to the liquid form all the gases then known with +the exception of six; while a large number of these substances were +still further reduced, by the application of the extreme degrees of +cold now attained, to the condition of solids. The six gases which still +proved intractable, and which hence came to be spoken of as "permanent +gases," were nitrous oxide, marsh gas, carbonic oxide, oxygen, nitrogen, +and hydrogen. + +These six refractory gases now became a target for the experiments of a +host of workers in all parts of the world. The resources of mechanical +ingenuity of the time were exhausted in the effort to produce low +temperatures on the one hand and high pressures on the other. Thus +Andrews, in England, using the bath of solid carbonic acid and ether +which Thilorier had discovered, and which produces a degree of cold +of--80 deg. Centigrade, applied a pressure of five hundred atmospheres, or +nearly four tons to the square inch, without producing any change of +state. Natterer increased this pressure to two thousand seven hundred +atmospheres, or twenty-one tons to the square inch, with the same +negative results. The result of Andrews' experiments in particular was +the final proof of what Cagniard de la Tour had early suspected +and Faraday had firmly believed, that pressure alone, regardless of +temperature, is not sufficient to reduce a gas to the liquid state. In +other words, the fact of a so-called "critical temperature," varying +for different substances, above which a given substance is always a gas, +regardless of pressure, was definitively discovered. It became clear, +then, that before the resistant gases would be liquefied means of +reaching extremely low temperatures must be discovered. And for this, +what was needed was not so much new principles as elaborate and +costly machinery for the application of a principle long familiar--the +principle, namely, that an evaporating liquid reduces the temperature of +its immediate surroundings, including its own substance. + +Ingenious means of applying this principle, in connection with the means +previously employed, were developed independently by Pictet in Geneva +and Cailletet in Paris, and a little later by the Cracow professors +Wroblewski and Olzewski, also working independently. Pictet, working on +a commercial scale, employed a series of liquefied gases to gain lower +and lower temperatures by successive stages. Evaporating sulphurous acid +liquefied carbonic acid, and this in evaporating brought oxygen under +pressure to near its liquefaction point; and, the pressure being +suddenly released (a method employed in Faraday's earliest experiments), +the rapid expansion of the compressed oxygen liquefies a portion of +its substance. This result was obtained in 1877 by Pictet and Cailletet +almost simultaneously. Cailletet had also liquefied the newly discovered +acetylene gas. Five years later Wroblewski liquefied marsh gas, and the +following year nitrogen; while carbonic oxide and nitrous oxide yielded +to Olzewski in 1884. Thus forty years of effort had been required to +conquer five of Faraday's refractory gases, and the sixth, hydrogen, +still remains resistant. Hydrogen had, indeed, been seen to assume the +form of visible vapor, but it had not been reduced to the so-called +static state--that is, the droplets had not been collected in an +appreciable quantity, as water is collected in a cup. Until this should +be done, the final problem of the liquefaction of hydrogen could not be +regarded as satisfactorily solved. + +More than another decade was required to make this final step in the +completion, of Faraday's work. And, oddly enough, yet very fittingly, +it was reserved for Faraday's successor in the chair at the Royal +Institution to effect this culmination. Since 1884 Professor Dewar's +work has made the Royal Institution again the centre of low-temperature +research. By means of improved machinery and of ingenious devices for +shielding the substance operated on from the accession of heat, to which +reference will be made more in detail presently, Professor Dewar was +able to liquefy the gas fluorine, recently isolated by Moussan, and the +recently discovered gas helium in 1897. And in May, 1898, he was able to +announce that hydrogen also had yielded, and for the first time in +the history of science that* elusive substance, hitherto "permanently" +gaseous, was held as a tangible liquid in a cuplike receptacle; and this +closing scene of the long struggle was enacted in the same laboratory in +which Faraday performed the first liquefaction experiment with chlorine +just three-quarters of a century before. + +It must be noted, however, that this final stage in the liquefaction +struggle was not effected through the use of the principle of +evaporating liquids which has just been referred to, but by the +application of a quite different principle and its elaboration into a +perfectly novel method. This principle is the one established long ago +by Joule and Thomson (Lord Kelvin), that compressed gases when allowed +to expand freely are lowered in temperature. In this well-known +principle the means was at hand greatly to simplify and improve the +method of liquefaction of gases, only for a long time no one recognized +the fact. Finally, however, the idea had occurred to two men almost +simultaneously and quite independently. One of these was Professor +Linde, the well-known German experimenter with refrigeration processes; +the other, Dr. William Hampson, a young English physician. Each of these +men conceived the idea--and ultimately elaborated it in practice--of +accumulating the cooling effect of an expanding gas by allowing the +expansion to take place through a small orifice into a chamber in which +the coil containing the compressed gas was held. In Dr. Hampson's words: + +"The method consists in directing all the gas immediately after its +expansion over the coils which contain the compressed gas that is on its +way to the expansion-point. The cold developed by expansion in the first +expanded gas is thus communicated to the oncoming compressed gas, which +consequently expands from, and therefore to, a lower temperature +than the preceding portion. It communicates in the same way its own +intensified cold to the succeeding portion of compressed gas, which, in +its turn, is made colder, both before and after expansion, than any +that had gone before. This intensification of cooling goes on until the +expansion-temperature is far lower than it was at starting; and if +the apparatus be well arranged the effect is so powerful that even the +smaller amount of cooling due to the free expansion of gas through a +throttle-valve, though pronounced by Siemens and Coleman incapable +of being utilized, may be made to liquefy air without using other +refrigerants." + +So well is this principle carried out in Dr. Hamp-son's apparatus for +liquefying air that compressed air passing into the coil at ordinary +temperature without other means of refrigeration begins to liquefy in +about six minutes--a result that seems almost miraculous when it is +understood that the essential mechanism by which this is brought about +is contained in a cylinder only eighteen inches long and seven inches in +diameter. + +As has been said, it was by adopting this principle of self-intensive +refrigeration that Professor Dewar was able to liquefy hydrogen. More +recently the same result has been attained through use of the same +principle by Professor Ramsay and Dr. Travers at University College, +London, who are to be credited also with first publishing a detailed +account of the various stages of the process. It appears that the use of +the self-intensification principle alone is not sufficient with hydrogen +as it is with the less volatile gases, including air, for the reason +that at all ordinary temperatures hydrogen does not cool in expanding, +but actually becomes warmer. It is only after the compressed hydrogen +has been cooled by immersion in refrigerating media of very low +temperature that this gas becomes amenable to the law of cooling on +expansion. In the apparatus used at University College the coil of +compressed hydrogen is passed successively through (1) a jar containing +alcohol and solid carbonic acid at a temperature of--80 deg. Centigrade; (2) +a chamber containing liquid air at atmospheric pressure, and (3) +liquid air boiling in a vacuum bringing the temperature to perhaps 2050 +Centigrade before entering the Hampson coil, in which expansion and +the self-intensive refrigeration lead to actual liquefaction. With this +apparatus Dr. Travers succeeded in producing an abundant quantity of +liquid hydrogen for use in the experiments on the new gases that were +first discovered in the same laboratory through the experiments on +liquid air--gases about which I shall have something more to say in +another chapter. + + +PRINCIPLES AND EXPERIMENTS + +At first blush it seems a very marvellous thing, this liquefaction +of substances that under all ordinary conditions are gaseous. It is +certainly a little startling to have a cup of clear, water-like liquid +offered one, with the assurance that it is nothing but air; still more +so to have the same air presented in the form of a white "avalanche +snow." In a certain sense it is marvellous, because the mechanical +difficulties that have been overcome in reducing the air to these +unusual conditions are great. Yet, in another and broader view, there +is nothing more wonderful about liquid air than about liquid water, or +liquid mercury, or liquid iron. Long before air was actually liquefied, +it was perfectly understood by men of science that under certain +conditions it could be liquefied just as surely as water, mercury, iron, +and every other substance could be brought to a similar state. This +being known, and the principles involved understood, had there been +nothing more involved than the bare effort to realize these conditions +all the recent low-temperature work would have been mere scientific +child's-play, and liquid air would be but a toy of science. But in point +of fact there are many other things than this involved; new principles +were being searched for and found in the course of the application of +the old ones; new light was being thrown into many dark corners; new +fields of research, some of them as yet barely entered, were being +thrown open to the investigator; new applications of energy, of vast +importance not merely in pure science but in commercial life as well, +were being made available. That is why the low-temperature work must be +regarded as one of the most important scientific accomplishments of our +century. + +At the very outset it was this work in large measure which gave the +final answer to the long-mooted question as to the nature of heat, +demonstrating the correctness of Count Rumford's view that heat is +only a condition not itself a substance. Since about the middle of the +century this view, known as the mechanical theory of heat, has been the +constant guide of the physicists in all their experiments, and any +one who would understand the low-temperature phenomena must keep this +conception of the nature of heat clearly and constantly in mind. To +understand the theory, one must think of all matter as composed +of minute isolated particles or molecules, which are always in +motion--vibrating, if you will. He must mentally magnify and +visualize these particles till he sees them quivering before him, +like tuning-forks held in the hand. Remember, then, that, like the +tuning-fork, each molecule would, if left to itself, quiver less and +less violently, until it ran down altogether, but that the motion thus +lessening is not really lost. It is sent out in the form of ether waves, +which can set up like motion in any other particles which they reach, be +they near or remote; or it is transmitted as a direct push--a kick, +if you will--to any other particle with which the molecule comes in +physical contact. + +But note now, further, that our molecule, while incessantly giving out +its energy of motion in ether waves and in direct pushes, is at the same +time just as ceaslessly receiving motion from the ether waves made by +other atoms, and by the return push of the molecules against which it +pushes. In a word, then, every molecule of matter is at once a centre +for the distribution of motion (sending out impulses which affect, +sooner or later, every other atom of matter in the universe), and, from +the other point of view, also a centre for the reception of motion from +every direction and from every other particle of matter in the universe. +Whether any given molecule will on the whole gain motion or lose it +depends clearly on the simple mechanical principles of give and take. + +From equally familiar mechanical principles, it is clear that our +vibrating molecule, in virtue of its vibrations, is elastic, tending to +be thrown back from every other molecule with which it comes in contact, +just as a vibrating tuning-fork kicks itself away from anything it +touches. And of course the vigor of the recoil will depend upon the +vigor of the vibration and the previous movements. But since these +movements constitute temperature, this is another way of saying that +the higher the temperature of a body the more its molecules will tend to +spring asunder, such separation in the aggregate constituting expansion +of the mass as a whole. Thus the familiar fact of expansion of a body +under increased temperature is explained. + +But now, since all molecules are vibrating, and so tending to separate, +it is clear that no unconfined mass of molecules would long remain in +contiguity unless some counter influence tended to draw them together. +Such a counter influence in fact exists, and is termed the "force" of +cohesion. This force is a veritable gravitation influence, drawing every +molecule towards every other molecule. Possibly it is identical with +gravitation. It seems subject to some law of decreasing in power with +the square of the distance; or, at any rate, it clearly becomes less +potent as the distance through which it operates increases. + +Now, between this force of cohesion which tends to draw the molecules +together, and the heat vibrations which tend to throw the molecules +farther asunder, there seems to be an incessant battle. If cohesion +prevails, the molecules are held for the time into a relatively fixed +system, which we term the solid state. If the two forces about balance +each other, the molecules move among themselves more freely but maintain +an average distance, and we term the condition the liquid state. But if +the heat impulse preponderates, the molecules (unless restrained from +without) fly farther and farther asunder, moving so actively that when +they collide the recoil is too great to be checked by cohesion, and this +condition we term the gaseous state. + +Now after this statement, it is clear that what the low-temperature +worker does when he would liquefy a gas is to become the champion of the +force of cohesion. He cannot directly aid it, for so far as is known it +is an unalterable quantity, like gravitation. But he can accomplish the +same thing indirectly by weakening the power of the rival force. Thus, +if he encloses a portion of gas in a cylinder and drives a piston down +against it, he is virtually aiding cohesion by forcing the molecules +closer together, so that the hold of cohesion, acting through a less +distance, is stronger. What he accomplishes here is not all gain, +however, for the bounding molecules, thus jammed together, come in +collision with one another more and more frequently, and thus their +average activity of vibration is increased and not diminished; in +other words, the temperature of the gas has risen in virtue of the +compression. Compression alone, then, will not avail to enable cohesion +to win the battle. + +But the physicist has another resource. He may place the cylinder of gas +in a cold medium, so that the heat vibrations sent into it will be less +vigorous than those it sends out. That is a blow the molecule cannot +withstand. It is quite impotent to cease sending out the impulses +however little comes in return; hence the aggregate motion becomes less +and less active, until finally the molecule is moving so sluggishly +that when it collides with its fellow cohesion is able to hold it there. +Cohesion, then, has won the battle, and the gas has become a liquid. + +Such, stated in terms of the mechanical theory of heat, is what is +brought to pass when a gas is liquefied in the laboratory of the +physicist. It remains only to note that different chemical substances +show the widest diversity as to the exact point of temperature at which +this balance of the expansive and cohesive tendencies is affected, but +that the point, under uniform conditions of pressure, is always the same +for the same substance. This diversity has to do pretty clearly with the +size of the individual molecules involved; but its exact explanation is +not yet forthcoming, and, except in a general way, the physicist +would not be able to predict the "critical temperature" of any new gas +presented to him. But once this has been determined by experiment, he +always knows just what to expect of any given substance. He knows, for +example, that in a mixture of gases hydrogen would still remain gaseous +after all the others had assumed the liquid state, and most of them the +solid state as well. + +These mechanical conceptions well in mind, it is clear that what the +would-be liquefier of gases has all along sought to attain is merely +the insulation of the portion of matter with which he worked against the +access of heat-impulse from its environment. It is clear that were any +texture known which would permit a heat-impulse to pass through it in +one direction only, nothing more would be necessary than to place a +portion of gas in such a receptacle of this substance, so faced as to +permit egress but not entrance of the heat, and the gas thus enclosed, +were it hydrogen itself, would very soon become liquid and solid, +through spontaneous giving off of its energy, without any manipulation +whatever. Contrariwise, were the faces of the receptacle reversed, a +piece of iron placed within it would be made red-hot and melted though +the receptacle were kept packed in salt and ice and no heat applied +except such as came from this freezing mixture. One could cook a +beefsteak with a cake of ice had he but such a material as this with +which to make his stove. Not even Rumford or our modern Edward Atkinson +ever dreamed of such economy of fuel as that. + +But, unfortunately, no such substance as this is known, nor, indeed, any +substance that will fully prevent the passage of heat-impulses in either +direction. Hence one of the greatest tasks of the experimenters has +been to find a receptacle that would insulate a cooled substance even +partially from the incessant bombardment of heat-impulses from without. +It is obvious that unless such an insulating receptacle could be +provided none of the more resistent gases, such as oxygen, could be +long kept liquid, even when once brought to that condition, since an +environment of requisite frigidity could not practicably be provided. + +But now another phase of the problem presents itself to the +experimenter. Oxygen has assumed the quiescent liquid state, to be +sure, but in so doing it has fallen below the temperature of its cooling +medium; hence it is now receiving from that medium more energy of +vibration than it gives, and unless this is prevented very soon its +particles will again have power to kick themselves apart and resume the +gaseous state. Something, then, must be done to insulate the liquefied +gas, else it will retain the liquid state for too short a time to be +much experimented with. How might such insulation be accomplished? + +The most successful attack upon this important problem has been made by +Professor Dewar. He invented a receptacle for holding liquefied gases +which, while not fulfilling the ideal conditions referred to above, yet +accomplishes a very remarkable degree of heat insulation. In consists of +a glass vessel with double walls, the space between which is rendered +a vacuum of the highest practicable degree. This vacuum, containing +practically no particles of matter, cannot, of course, convey +heat-impulses to or from the matter in the receptacle with any degree +of rapidity. Thus one of the two possible means of heat transfer is shut +off and a degree of insulation afforded the liquefied substance. But +of course the other channel, ether radiation, remains. Even this may be +blocked to a large extent, however, by leaving a trace of mercury vapor +in the vacuum space, which will be deposited as a fine mirror on +the inner surface of the chamber. This mirror serves as an admirable +reflector of the heat-rays that traverse the vacuum, sending more +than half of them back again. So, by the combined action of vacuum and +mirror, the amount of heat that can penetrate to the interior of the +receptacle is reduced to about one-thirtieth of what would enter an +ordinary vessel. In other words, a quantity of liquefied gas which would +evaporate in one minute from an ordinary vessel will last half an hour +in one of Professor Dewar's best vacuum vessels. Thus in one of these +vessels a quantity of liquefied air, for example, can be kept for a +considerable time in an atmosphere at ordinary temperature, and will +only volatilize at the surface, like water under the same conditions, +though of course more rapidly; whereas the same liquid in an ordinary +vessel would boil briskly away, like water over a fire. Only, be it +remembered, the air in "boiling" is at a temperature of about one +hundred and eighty degrees below zero, so that it would instantly freeze +almost any substance placed into it. A portion of alcohol poured on its +surface will be changed quickly into a globule of ice, which will +rattle about the sides of the vessel like a marble. That is not what one +ordinarily thinks of as a "boiling" temperature. + +If the vacuum vessel containing a liquefied gas be kept in a cold +medium, and particularly if two vacuum tubes be placed together, so that +no exposed surface of liquid remains, a portion of liquefied air, for +example, may be kept almost indefinitely. Thus it becomes possible +to utilize the liquefied gas for experimental investigation of the +properties of matter at low temperatures that otherwise would be quite +impracticable. Great numbers of such experiments have been performed in +the past decade or so by all the workers with low temperatures already +mentioned, and by various others, including, fittingly enough, the +holder of the Rumford professorship of experimental physics at Harvard, +Professor Trowbridge. The work of Professor Dewar has perhaps been the +most comprehensive and varied, but the researches of Pictet, Wroblewski, +and Olzewski have also been important, and it is not always possible +to apportion credit for the various discoveries accurately, since +the authorities themselves are in unfortunate disagreement in several +questions of priority. But in any event, such questions of exact +priority have no great interest for any one but the persons directly +involved. We may quite disregard them here, confining attention to the +results themselves, which are full of interest. + +The questions investigated have to do with the physical properties, +such as electrical conductivity, magnetic condition, light-absorption, +cohesion, and chemical affinities of matter at excessively low +temperatures. It is found that in all these regards most substances are +profoundly modified when excessively cooled. Thus if a piece of any pure +metal is placed in an electric circuit and plunged into liquid air, its +resistance to the passage of the electricity steadily decreases as the +metal cools, until at the temperature of the liquid it is very trifling +indeed. The conclusion seems to be justified that if the metal could be +still further cooled until it reached the theoretical "absolute zero," +or absolutely heatless condition, the electrical resistance would also +be nil. So it appears that the heat vibrations of the molecules of a +pure metal interfere with the electrical current. The thought suggests +itself that this may be because the ether waves set up by the vibrating +molecules conflict with the ether strain which is regarded by some +theorists as constituting the electrical "current." But this simple +explanation falters before further experiments which show, paradoxically +enough, that the electrical resistance of carbon exactly reverses what +has just been said of pure metals, becoming greater and greater as the +carbon is cooled. If an hypothesis were invented to cover this case +there would still remain a puzzle in the fact that alloys of metals +do not act at all like the pure metals themselves, the electrical +resistance of such alloys being, for the most part, unaffected by +changed temperature. On the whole, then, the facts of electrical +conduction at low temperatures are quite beyond the reach of present +explanation. They must await a fuller knowledge of molecular conditions +in general than is at present available--a knowledge to which the +low-temperature work itself seems one of the surest channels. + +Even further beyond the reach of present explanation are the facts as to +magnetic conditions at low temperatures. Even as to the facts themselves +different experimenters have differed somewhat, but the final conclusion +of Professor Dewar is that, after a period of fluctuation, the power of +a magnet repeatedly subjected to a liquid-air bath becomes permanently +increased. Various substances not markedly magnetic at ordinary +temperatures become so when cooled. Among these, as Professor Dewar +discovered, is liquid oxygen itself. Thus if a portion of liquid air be +further cooled until it assumes a semi-solid condition, the oxygen may +be drawn from the mass by a magnet, leaving a pure nitrogen jelly. These +facts are curious enough, and full of suggestion, but like all other +questions having to do with magnetism, they hold for the present +generation the double fascination of insoluble mystery. To be sure, one +may readily enough suggest that if magnetism be really a whirl in the +ether, this whirl is apparently interfered with by the waves of radiant +heat; or, again, that magnetism is presumably due to molecular motions +which are apparently interfered with by another kind of molecular +motions which we call heat vibrations; but there is a vagueness about +the terms of such guesses that leaves them clearly within the category +of explanations that do not explain. + +When it comes to the phenomena of light, we can, as is fitting, see +our way a little more clearly, since, thanks to Thomas Young and his +successors, we know pretty definitely what light really is. So when +we learn that many substances change their color utterly at low +temperatures--red things becoming yellow and yellow things white, +for example--we can step easily and surely to at least a partial +explanation. We know that the color of any object depends simply +upon the particular ether waves of the spectrum which that particular +substance absorbs; and it does not seem anomalous that molecules packed +close together at--180 deg. of temperature should treat the ether waves +differently than when relatively wide apart at an ordinary temperature. +Yet, after all, that may not be the clew to the explanation. The packing +of the molecules may have nothing to do with it. The real explanation +may lie in the change of the ether waves sent out by the vibrating +molecule; indeed, the fact that the waves of radiant heat and those of +light differ only in amplitude lends color to this latter supposition. +So the explanation of the changed color of the cooled substance is at +best a dubious one. + +Another interesting light phenomenon is found in the observed fact that +very many substances become markedly phosphorescent at low temperatures. +Thus, according to Professor Dewar, "gelatine, celluloid, paraffine, +ivory, horn, and india-rubber become distinctly luminous, with a bluish +or greenish phosphorescence, after cooling to--180 deg. and being stimulated +by the electric light." The same thing is true, in varying degrees, +of alcohol, nitric acid, glycerine, and of paper, leather, linen, +tortoise-shell, and sponge. Pure water is but slightly luminous, whereas +impure water glows brightly. On the other hand, alcohol loses its +phosphorescence when a trace of iodine is added to it. In general, +colored things are but little phosphorescent. Thus the white of egg is +very brilliant but the yolk much less so. Milk is much brighter than +water, and such objects as a white flower, a feather, and egg-shell +glow brilliantly. The most remarkable substances of all, says Professor +Dewar, whom I am all along quoting, are "the platinocyanides among +inorganic compounds and the ketonic compounds among organic. Ammonium +platinocyanide, cooled while stimulated by arc light, glows fully +at--180 deg.; but on warming it glows like a lamp. It seems clear," +Professor Dewar adds, "that the substance at this low temperature must +have acquired increased power of absorption, and it may be that at +the same time the factor of molecular friction or damping may have +diminished." The cautious terms in which this partial explanation is +couched suggest how far we still are from a full understanding of the +interesting phenomena of phosphorescence. That a molecule should be +able to vibrate in such a way as to produce the short waves of light, +dissevered from the usual linking with the vibrations represented by +high temperature, is one of the standing puzzles of physics. And the +demonstrated increase of this capacity at very low temperatures only +adds to the mystery. + +There are at least two of the low-temperature phenomena, however, +that seem a little less puzzling--the facts, namely, that cohesion and +rigidity of structure are increased when a substance is cooled and that +chemical activity is very greatly reduced, in fact almost abolished. +This is quite what one would expect _a priori_--though no wise man would +dwell on his expectation in advance of the experiments--since the whole +question of liquids and solids _versus_ gases appears to be simply a +contest between cohesive forces that are tending to draw the molecules +together and the heat vibration which is tending to throw them apart. +As a substance changes from gas to liquid, and from liquid to solid, +contracting meantime, simply through the lessening of the heat +vibrations of its molecules, we might naturally expect that the solid +would become more and more tenacious in structure as its molecules came +closer and closer together, and at the same time became less and less +active, as happens when the solid is further cooled. And for once +experiment justifies the expectation. Professor De-war found that the +breaking stress of an iron wire is more than doubled when the wire +is cooled to the temperature of liquid air, and all other metals are +largely strengthened, though none other to quite the same degree. +He found that a spiral spring of fusible metal, which at ordinary +temperature was quickly drawn out into a straight wire by a weight +of one ounce, would, when cooled to -182 deg, support a weight of two +pounds, and would vibrate like a steel spring so long as it was cool. +A bell of fusible metal has a distinct metallic ring at this low +temperature; and balls of iron, tin, lead, or ivory cooled to -182 +deg and dropped from a height, "in all cases have the rebound greatly +increased. The flattened surface of the lead is only one-third what it +would be at ordinary temperature." "These conditions are due solely to +the cooling, and persist only while the low temperature lasts." + +If this increased strength and hardness of a contracted metal are +what one would expect on molecular principles, the decreased chemical +activity at low temperatures is no less natural-seeming, when one +reflects how generally chemical phenomena are facilitated by the +application of heat. In point of fact, it has been found that at the +temperature of liquid hydrogen practically all chemical activity +is abolished, the unruly fluorine making the only exception. The +explanation hinges on the fact that every atom, of any kind, has +power to unite with only a limited number of other atoms. When the +"affinities" of an atom are satisfied, no more atoms can enter into the +union unless some atoms already there be displaced. Such displacement +takes place constantly, under ordinary conditions of temperature, +because the vibrating atoms tend to throw themselves apart, and other +atoms may spring in to take the places just vacated--such interchange, +in fact, constituting the essence of chemical activity. But when the +temperature is reduced the heat-vibration becomes insufficient to +throw the atoms apart, hence any unions they chance to have made are +permanent, so long as the low temperature is maintained. Thus it is that +substances which attack one another eagerly at ordinary temperatures +will lie side by side, utterly inert, at the temperature of liquid air. + +Under certain conditions, however, most interesting chemical experiments +have been made in which the liquefied gases, particularly oxygen, are +utilized. Thus Olzewski found that a bit of wood lighted and thrust into +liquid oxygen burns as it would in gaseous oxygen, and a red-hot iron +wire thrust into the liquid burns and spreads sparks of iron. But more +novel still was Dewar's experiment of inserting a small jet of ignited +hydrogen into the vessel of liquid oxygen; for the jet continued to +burn, forming water, of course, which was carried away as snow. The idea +of a gas-jet burning within a liquid, and having snow for smoke, is +not the least anomalous of the many strange conceptions that the +low-temperature work has made familiar. + + +PRACTICAL RESULTS AND ANTICIPATIONS + +Such are some of the strictly scientific results of the low-temperature +work. But there are other results of a more directly practical +kind--neither more important nor more interesting on that account, to +be sure, but more directly appealing to the generality of the +non-scientific public. Of these applications, the most patent and the +first to be made available was the one forecast by Davy from the very +first--namely, the use of liquefied gases in the refrigeration of +foods. Long before the more resistant gases had been liquefied, the more +manageable ones, such as ammonia and sulphurous acid, had been utilized +on a commercial scale for refrigerating purposes. To-day every +brewery and every large cold-storage warehouse is supplied with such +a refrigerator plant, the temperature being thus regulated as is not +otherwise practicable. Many large halls are cooled in a similar manner, +and thus made comfortable in the summer. Ships carrying perishables +have the safety of their cargoes insured by a refrigerator plant. In all +large cities there are ice manufactories using the same method, and of +late even relatively small establishments, hotels, and apartment houses +have their ice-machine. It seems probable that before long all such +buildings and many private dwellings will be provided with a cooling +apparatus as regularly as they are now equipped with a heating +apparatus. + +The exact details of the various refrigerator machines of course vary, +but all of them utilize the principles that the laboratory workers first +established. Indeed, the entire refrigerator industry, now assuming +significant proportions, may be said to be a direct outgrowth of that +technical work which Davy and Faraday inaugurated and prosecuted at the +Royal Institution--a result which would have been most gratifying to the +founder of the institution could he have forecast it. The usual means +of distributing the cooling fluids in the commercial plants is by +the familiar iron pipes, not dissimilar in appearance (when not in +operation) to the familiar gas, water, and steam pipes. When operating, +however, the pipes themselves are soon hidden from view by the thick +coating of frost which forms over them. In a moist beer-cellar +this coating is often several inches in thickness, giving a very +characteristic and unmistakable appearance. + +Another commercial use to which refrigerator machines are now put is in +the manufacture of various drugs, where absolute purity is desirable. +As different substances congeal at different temperatures, but the same +substances at uniform pressure always at the same temperature, a +means is afforded of freeing a drug from impurities by freezing, where +sometimes the same result cannot be accomplished with like thoroughness +by any other practicable means. Indeed, by this means impurities have +been detected where not previously suspected. And Professor Ramsay has +detected some new elementary substances even, as constituents of the +air, which had previously not been dissociated from the nitrogen with +which they are usually mixed. + +Such applications of the refrigerator principles as these, however, +though of vast commercial importance, are held by many enthusiasts to +be but a bagatelle compared with other uses to which liquefied gases +may some time be put. Their expectations are based upon the enormous +potentialities that are demonstrably stored in even a tiny portion of, +say, liquefied air. These are, indeed, truly appalling. Consider, for +example, a portion of air at a temperature above its critical point, to +which, as in Thilorier's experiments, a pressure of thirty-one tons to +the square inch of the encompassing wall is being applied. Recall that +action and reaction are equal, and it is apparent that the gas itself is +pushing back--struggling against being compressed, if you will--with an +equal power. Suppose the bulk of the gas is such that at this pressure +it occupies a cubical space six inches on a side--something like the +bulk of a child's toy balloon, let us say. Then the total outward +pressure which that tiny bulk of gas exerts, in its desperate molecular +struggle, is little less than five thousand tons. It would support an +enormous building without budging a hair's-breadth. If the building +weighed less than five thousand tons it would be lifted by the gas; if +much less it would be thrown high into the air as the gas expanded. It +gives one a new sense of the power of numbers to feel that infinitesimal +atoms, merely by vibrating in unison, could accomplish such a result. + +But now suppose our portion of gas, instead of being placed under our +hypothetical building, is plunged into a cold medium, which will permit +its heat-vibrations to exhaust themselves without being correspondingly +restored. Then, presently, the temperature is lowered below the critical +point, and, presto! the mad struggle ceases, the atoms lie amicably +together, and the gas has become a liquid. What a transformed thing +it is now. Instead of pressing out with that enormous force, it has +voluntarily contracted as the five thousand tons pressure could not +make it do; and it lies there now, limpid and harmless-seeming, in the +receptacle, for all the world like so much water. + +And, indeed, the comparison with water is more than superficial, for +in a cup of water also there are wonderful potentialities, as every +steam-engine attests. But an enormous difference, not in principle but +in practical applications, exists in the fact that the potentialities +of the water cannot be utilized until relatively high temperatures are +reached. Costly fuel must be burned and the heat applied to the water +before it can avail to do its work. But suppose we were to place our +portion of liquid air, limpid and water-like, in the cylinder of a +locomotive, where the steam of water ordinarily enters. Then, though no +fuel were burned--though the entire engine stood embedded in the snow +of an arctic winter--it would be but a few moments before the liquid air +would absorb even from this cold medium heat enough to bring it above +its critical temperature; and, its atoms now dancing apart once more and +re-exerting that enormous pressure, the piston of the engine would be +driven back and then the entire cylinder burst into fragments as the +gas sought exit. In a word, then, a portion of liquid air has a store +of potential energy which can be made kinetic merely by drawing upon +the boundless and free supply of heat which is everywhere stored in the +atmosphere we breathe and in every substance about us. The difficulty +is, not to find fuel with which to vaporize it, as in case of water, +but to keep the fuel from finding it whether or no. Were liquid air in +sufficient quantities available, the fuel problem would cease to +have any significance. But of course liquid air is not indefinitely +available, and exactly here comes the difficulty with the calculations +of many enthusiasts who hail liquefied gas as the motive power of the +near future. For of course in liquefying the air power has been applied, +for the moment wasted, and unless we can get out of the liquid more +energy than we have applied to it, there is no economy of power in +the transaction. Now the simplest study of the conditions, with the +mechanical theory of matter in mind, makes it clear that this is +precisely what one can never hope to accomplish. Action and reaction are +equal and in opposite directions at all stages of the manipulation, and +hence, under the most ideal conditions, we must expect to waste as much +work in condensing a gas (in actual practice more) as the condensed +substance can do in expanding to the original volume. Those enthusiasts +who have thought otherwise, and who have been on the point of perfecting +an apparatus which will readily and cheaply produce liquid air after +the first portion is produced, are really but following the old +perpetual-motion-machine will-o'-the-wisp. + +It does not at all follow from this, however, that the energies of +liquefied air may not be utilized with enormous advantage. It is not +always the cheapest form of power-transformer that is the best for all +purposes, as the use of the electrical storage battery shows. And so it +is quite within the possibilities that a multitude of uses may be +found for the employment of liquid air as a motive power, in which its +condensed form, its transportability or other properties will give +it precedence over steam or electricity. It has been suggested, for +example, that liquefied gas would seem to afford the motive power par +excellence for the flying-machine, once that elusive vehicle is well in +harness, since one of the greatest problems here is to reduce the weight +of the motor apparatus. In a less degree the same problem enters into +the calculations of ships, particularly ships of war; and with them also +it may come to pass that a store of liquid air (or other gas) may come +to take the place of a far heavier store of coal. It is even within the +possibilities that the explosive powers of the same liquid may take the +place of the great magazines of powder now carried on war-ships; for, +under certain conditions, the liquefied gas will expand with explosive +suddenness and violence, an "explosion" being in any case only a very +sudden expansion of a confined gas. The use of the compressed air in the +dynamite guns, as demonstrated in the Cuban campaign, is a step in this +direction. And, indeed, the use of compressed air in many commercial +fields already competing with steam and electricity is a step towards +the use of air still further compressed, and cooled, meantime, to a +condition of liquidity. The enormous advantages of the air actually +liquefied, and so for the moment quiescent, over the air merely +compressed, and hence requiring a powerful retort to hold it, are patent +at a glance. But, on the other hand, the difficulty of keeping it liquid +is a disadvantage that is equally patent. How the balance will be struck +between these contending advantages and disadvantages it remains for +the practical engineering inventors of the future--the near future, +probably--to demonstrate. + +Meantime there is another line of application of the ideas which the +low-temperature work has brought into prominence which has a peculiar +interest in the present connection because of its singularly Rumfordian +cast, so to speak, I mean the idea of the insulation of cooled or heated +objects in the ordinary affairs of life, as, for example, in cooking. +The subject was a veritable hobby with the founder of the Royal +Institution all his life. He studied the heat-transmitting and +heat-reflecting properties of various substances, including such +directly practical applications as rough surfaces _versus_ smooth +surfaces for stoves, the best color for clothing in summer and in +winter, and the like. He promulgated his ideas far and wide, and +demonstrated all over Europe the extreme wastefulness of current methods +of using fuel. To a certain extent his ideas were adopted everywhere, +yet on the whole the public proved singularly apathetic; and, especially +in America, an astounding wastefulness in the use of fuel is the general +custom now as it was a century ago. A French cook will prepare an +entire dinner with a splinter of wood, a handful of charcoal, and a +half-shovelful of coke, while the same fuel would barely suffice to +kindle the fire in an American cook-stove. Even more wonderful is the +German stove, with its great bulk of brick and mortar and its glazed +tile surface, in which, by keeping the heat in the room instead of +sending it up the chimney, a few bits of compressed coal do the work of +a hodful. + +It is one merit of the low-temperature work, I repeat, to have called +attention to the possibilities of heat insulation in application to "the +useful purposes of life." If Professor Dewar's vacuum vessel can reduce +the heat-transmitting capacity of a vessel by almost ninety-seven per +cent., why should not the same principle, in modified form, be applied +to various household appliances--to ice-boxes, for example, and +to cooking utensils, even to ovens and cook-stoves? Even in the +construction of the walls of houses the principles of heat insulation +might advantageously be given far more attention than is usual at +present; and no doubt will be so soon as the European sense of economy +shall be brought home to the people of the land of progress and +inventions. The principles to be applied are already clearly to hand, +thanks largely to the technical workers with low temperatures. It +remains now for the practical inventors to make the "application to the +useful purposes of life." The technical scientists, ignoring the example +which Rumford and a few others have set, have usually no concern with +such uninteresting concerns. + +For the technical scientists themselves, however, the low-temperature +field is still full of inviting possibilities of a strictly technical +kind. The last gas has indeed been liquefied, but that by no means +implies the last stage of discovery. With the successive conquest of +this gas and of that, lower and lower levels of temperature have been +reached, but the final goal still lies well beyond. This is the north +pole of the physicist's world, the absolute zero of temperature--the +point at which the heat-vibrations of matter are supposed to be +absolutely stilled. Theoretically this point lies 2720 below the +Centigrade zero. With the liquefaction of hydrogen, a temperature of +about -253 deg or -254 deg Centigrade has been reached. So the gap +seems not so very great. But like the gap that separated Nansen from the +geographical pole, it is a very hard road to travel. How to compass it +will be the study of all the low-temperature explorers in the immediate +future. Who will first reach it, and when, and how, are questions for +the future to decide. + +And when the goal is reached, what will be revealed? That is a question +as full of fascination for the physicist as the north-pole mystery +has ever been for the generality of mankind. In the one case as in +the other, any attempt to answer it to-day must partake largely of the +nature of a guess, yet certain forecasts may be made with reasonable +probability. Thus it can hardly be doubted that at the absolute zero all +matter will have the form which we term solid; and, moreover, a degree +of solidity, of tenacity and compactness greater than ever otherwise +attained. All chemical activity will presumably have ceased, and any +existing compound will retain unaltered its chemical composition so +long as absolute zero pertains; though in many, if not in all cases, +the tangible properties of the substance--its color, for example, and +perhaps its crystalline texture--will be so altered as to be no longer +recognizable by ordinary standards, any more than one would ordinarily +recognize a mass of snowlike crystals as air. + +It has, indeed, been suggested that at absolute zero all matter may take +the form of an impalpable powder, the forces of cohesion being destroyed +with the vibrations of heat. But experiment seems to give no warrant to +this forecast, since cohesion seems to increase exactly in proportion +to the decrease of the heat-vibrations. The solidity of the meteorites +which come to the earth out of the depths of space, where something +approaching the zero temperature is supposed to prevail, also +contradicts this assumption. Still less warrant is there for a visionary +forecast at one time entertained that at absolute zero matter will +utterly disappear. This idea was suggested by the observation, which +first gave a clew to the existence of the absolute zero, that a gas at +ordinary temperatures and at uniform pressure contracts by 1-27 2d of +its own bulk with each successive degree of lowered temperature. If this +law held true for all temperatures, the gas would apparently contract to +nothingness when the last degree of temperature was reached, or at least +to a bulk so insignificant that it would be inappreciable by standards +of sense. But it was soon found by the low-temperature experimenters +that the law does not hold exactly at extreme temperatures, nor does it +apply at all to the rate of contraction which the substance shows after +it assumes the liquid and solid conditions. So the conception of the +disappearance of matter at zero falls quite to the ground. + +But one cannot answer with so much confidence the suggestion that at +zero matter may take on properties hitherto quite unknown, and making +it, perhaps, differ as much from the conventional solid as the solid +differs from the liquid, or this from the gas. The form of vibration +which produces the phenomena of temperature has, clearly, a determining +share in the disposal of molecular relations which records itself to our +senses as a condition of gaseousness, liquidity, or solidity; hence it +would be rash to predict just what inter-molecular relations may not +become possible when the heat-vibration is altogether in abeyance. That +certain other forms of activity may be able to assert themselves in +unwonted measure seems clearly forecast in the phenomena of increased +magnetism, and of phosphorescence at low temperatures above outlined. +Whether still more novel phenomena may put in an appearance at the +absolute zero, and if so, what may be their nature, are questions that +must await the verdict of experiment. But the possibility that this may +occur, together with the utter novelty of the entire subject, gives +the low-temperature work precedence over almost every other subject +now before the world for investigation (possible exceptions being +radio-activity and bacteriology). The quest of the geographical pole is +but a child's pursuit compared with the quest of the absolute zero. In +vital interest the one falls as far short of the other as the cold of +frozen water falls short of the cold of frozen air. + +Where, when, and by whom the absolute zero will be first reached are +questions that may be answered from the most unexpected quarter. But it +is interesting to know that great preparations are being made today in +the laboratories of the Royal Institution for a further attack upon the +problem. Already the research equipment there is the best in the world +in this field, and recently this has been completely overhauled and +still further perfected. It would not be strange, then, in view of past +triumphs, if the final goal of the low-temperature workers should be +first reached in the same laboratory where the outer territories of +the unknown land were first penetrated three-quarters of a century ago. +There would seem to be a poetic fitness in the trend of events should it +so transpire. But of course poetic fitness does not always rule in the +land of science. + + + + +IV. SOME PHYSICAL LABORATORIES AND PHYSICAL PROBLEMS + + +SIR NORMAN LOCKYER AND SOLAR CHEMISTRY + +SIR NORMAN LOCKYER is professor of astronomical physics and director +of the solar observatory at the Royal College of Science in South +Kensington. Here it is that his chief work has been done for some thirty +years past. The foundation-stone of that work is spectroscopic study of +the sun and stars. In this study Professor Lockyer was a pioneer, and he +has for years been recognized as the leader. But he is no mere observer; +he is a generalizer as well; and he long since evolved revolutionary +ideas as to the origin of the sidereal and solar systems. + +For a man whose chief occupation is the study of the sun and stars, +smoky, foggy, cloudy London may seem a strange location. I asked +Professor Lockyer about this, and his reply was most characteristic. +"The fact is," he said, "the weather here is too fine from one point of +view: my working staff is so small, and the number of working nights so +large, that most of the time there is no one about to do anything during +the day. Then, another thing, here at South Kensington I am in touch +with my colleagues in the other departments--physics, chemistry, and so +forth--and can at once draw upon their special knowledge for aid on any +obscure point in their lines that may crop up. If we were out in the +country this would not be so. You see, then, that it is a choice between +weather and brains. I prefer the brains." + +Professor Lockyer went on to state, however, that he is by no means +altogether dependent upon the observations made at South Kensington. For +certain purposes the Royal Observatory at Greenwich is in requisition, +and there are three observatories at different places in India at which +photographs of the sun-spots and solar spectra are taken regularly. +From these combined sources photographs of the sun are forthcoming +practically every day of the year; to be accurate, on three hundred and +sixty days out of the three hundred and sixty-five. It was far +otherwise when Professor Lockyer first began his studies of the sun, as +observations were then made and recorded on only about one-third of the +days in each year. + +Exteriorly the observatory at South Kensington is not at all such a +place as one might expect to find. It is, in Professor Lockyer's own +words, "little more than a collection of sheds," but within these +alleged sheds may be found an excellent equipment of telescopes, both +refracting and reflecting, and of all other things requisite to the +peculiar study which forms the subject of special research here. + +I have had occasion again and again to call attention to this relatively +meagre equipment of the European institutions, but in no case, perhaps, +is the contrast more striking between the exterior appearance of a +famous scientific institution and the work that is being accomplished +within it than is shown in the case of the South Kensington observatory. +It should be added that this remark does not apply to the chief building +of the Royal College of Science itself. + +The theories for which Professor Lockyer has so long been famous are +well known to every one who takes much interest in the progress of +scientific ideas. They are notably the theory that there is a direct +causal association between the prevalence of sun-spots and terrestrial +weather; the theory of the meteoritic origin of all members of the +sidereal family; and the dissociation theory of the elements, according +to which our so-called elements are really compounds, capable of being +dissociated into simpler forms when subjected to extreme temperatures, +such as pertain in many stars. As I have said, these theories are by no +means new. Professor Lockyer has made them familiar by expounding them +for a full quarter of a century or more. But if not new, these theories +are much too important to have been accepted at once without a protest +from the scientific world. In point of fact, each of them has been met +with most ardent opposition, and it would, perhaps, not be too much to +say that not one of them is, as yet, fully established. It is of the +highest interest to note, however, that the multitudinous observations +bearing upon each of these topics during the past decade have tended, in +Professor Lockyer's opinion, strongly to corroborate each one of these +opinions. + +Two or three years ago Sir Norman Lockyer, in association with his son, +communicated to the Royal Society a paper in which the data recently +obtained as to the relation between sun-spots and the weather +in India--the field of observations having been confined to that +territory--are fully elaborated. A remarkable feature of the recent +work in that connection has been the proof, or seeming proof, that the +temperature of the sun fluctuates from year to year. At times when the +sun-spots are numerous and vigorous in their action, the spectrum of +the elements in these spots becomes changed. During the times of minimum +sun-spot activity the spectrum shows, for example, the presence of large +quantities of iron in these spots--of course in a state of vapor. But in +times of activity this iron disappears, and the lines which previously +vouched for it are replaced by other lines spoken of as the enhanced +lines of iron--that is to say, the lines which are believed to represent +the unknown substance or substances into which the iron has been +decomposed; and what is true of iron is true of various other elements +that are detected in the sun-spots. The explanation of this phenomena, +if Professor Lockyer reads the signs aright, is that during times of +minimum sun-spot activity the temperature of the sun-spots is relatively +cool, and that in times of activity the temperature becomes greatly +increased. One must come, therefore, to speaking of hot spots and cool +spots on the sun; although the cool spots, it will be understood, +would hardly be considered cool in the terrestrial sense, since their +temperature is sufficient to vaporize iron. + +Now the point of the recent observations is that the fluctuations in +the sun's heat, due to the periodic increase and subsidence of sun-spot +disturbances--such fluctuations having been long recognized as having +regular cyclic intervals of about eleven years--are instrumental in +effecting changes in the terrestrial weather. According to the paper +just mentioned, it would appear to be demonstrated that the periods +of decreased rainfall in India have a direct and relatively unvarying +relationship to the prevalence of the sun-spots, and that, therefore, it +has now become possible, within reasonable limits, to predict some years +in advance the times of famine in India. So important a conclusion as +this is certainly not to be passed over lightly, and all the world, +scientific and unscientific alike, will certainly watch with acute +interest for the verification of this seemingly startling practical +result of so occult a science as solar spectroscopy. + +The theory of the decomposition of the elements is closely bound up with +the meteoritic theory. In a word, it may be said of each that Professor +Lockyer is firmly convinced that all the evidence that has accumulated +in recent years is so strongly in favor as to bring these theories +almost to a demonstration. The essence of the meteoritic theory, it +will be recalled, is that all stars have their origin in nebulae which +consist essentially of clouds of relatively small meteorites. It will be +recalled further that Professor Lockyer long ago pointed out that +stars pass through a regular series of changes as to temperature, with +corresponding changes of structure, becoming for a time hotter and +hotter until a maximum is reached, and then passing through gradual +stages of cooling until their light dies out altogether. Very recently +Professor Lockyer has been enabled, through utilization of the multiform +records accumulated during years of study, to define the various typical +stages of the sidereal evolution; and not merely to define them but +to illustrate them practically by citing stars which belong to each +of these stages, and to give them yet clearer definition by naming the +various elements which the spectroscope reveals as present in each. + +His studies have shown that the elements do not always give the same +spectrum under all conditions; a result quite at variance with the +earlier ideas on the subject. Even in the terrestrial laboratory it +is possible to subject various metals, including iron, to temperatures +attained with the electric spark at which the spectrum becomes different +from that, for example, which was attained with the lower temperature +of the electric arc. Through these studies so-called series-spectra +have been attained for various elements, and a comparison of these +series-spectra with the spectra of various stars has led to the +conclusion that many of the unknown lines previously traced in the +spectra of such stars are due to the decomposition products of familiar +elements; all of which, of course, is directly in line of proof of the +dissociation hypothesis. + +Another important result of Professor Lockyer's very recent studies has +come about through observation of the sun in eclipse. A very interesting +point at issue all along has been the question as to what layers of the +sun's atmosphere are efficient in producing the so-called reverse lines +of the spectrum. It is now shown that the effect is not produced, as +formerly supposed, by the layers of the atmosphere lying just above the +region which Professor Lockyer long ago named the chromosphere, but by +the gases of higher regions. Reasoning from analogy, it may be supposed +that a corresponding layer of the atmosphere of other stars is the +one which gives us the reverse spectrum of those stars. The exact +composition of this layer of the sidereal atmosphere must, of course, +vary with the temperature of the different stars, but in no case can +we expect to receive from the spectroscope a full record of all the +substances that may be present in other layers of the atmosphere or in +the body of the star itself. Thus, for example, the ordinary Freuenhofer +spectrum of the sun shows us no trace of the element helium, though +through other observations at the time of eclipse Professor Lockyer had +discovered that element there, as we have seen, some thirty years before +anything was known of it on the earth. + +In a recent eclipse photographs were taken of the spectra of the lower +part of the sun's atmosphere by itself, and it was found that the +spectrum of this restricted area taken by itself gave the lines which +specialize the spectra of so different a star as Procyon. "I recognize +in the result," says Professor Lockyer, "a veritable Rosetta Stone which +will enable us to read the celestial hieroglyphics presented to us in +stellar spectra, and help us to study the spectra and to get at results +much more distinctly and certainly than ever before." + +But the most striking confirmation which the meteoritic hypothesis has +received has come to hand through study of the spectrum of the new star +which appeared in the constellation Perseus in February, 1901, and which +was so widely heralded everywhere in the public press. This star was +discovered on the morning of February 22d by star-gazers in Scotland, +and in America almost simultaneously. It had certainly not been +visible a few hours before, and it had blazed up suddenly to a greater +brilliancy than that of a first-magnitude star. At first it was +bluish-white in color, indicating an extremely high temperature, but +it rapidly subsided in brilliancy and assumed a red color as it cooled, +passing thus, in the course of a few days, through stages for which +ordinary stars require periods of many millions of years. + +The most interesting feature of the spectrum of this new star was the +fact that it showed both light and dark lines for the same substances, +the two lying somewhat apart. This means, being interpreted, that some +portions of a given substance are giving out light, thus producing +the bright lines of the spectrum, and that other portions of the same +substance are stopping certain rays of transmitted light, thus producing +the dark lines. The space between the bright and dark lines, being +measured, indicated that there was a differential motion between the +two portions of substance thus recorded of something like seven hundred +miles a second. This means, according to theory--and it seems hardly +possible to explain it otherwise--that two sidereal masses, one at least +of which was moving at an enormous rate of speed, had collided, such +collision, of course, being the cause of the incandescence that made the +mass suddenly visible from the earth as a new star. + +New stars are by no means every-day affairs, there having been but +thirty-two of them recorded in the world's history, and of these only +two have exceeded the present one in brilliancy. As a mere spectacle, +therefore, this new star was of great interest; but a far greater +importance attaches to it through the fact that it conforms so admirably +to the course that meteoritic hypothesis would predict for it. "That is +what confounds my opponents," said Professor Lockyer, in talking to me +about the new star. "Most of those who oppose my theory have not taken +the trouble to make observations for themselves, but have contented +themselves with falling back apparently on the postulate that because +a theory is new it must be wrong. Then, outside the scientific world, +comparatively few people appreciate the extreme parsimony of nature. +They expect, therefore, that when such a phenomenon as the appearance of +a new star occurs, the new-comer will establish new rules for itself and +bring chaos into the scientific world. But in point of fact nature never +does things in two ways if she can possibly do them in one, and the +most striking thing about the new stars is that all the phenomena they +present conform so admirably to the laws built up through observation of +the old familiar stars. As to our particular theories, we here at South +Kensington"--it will be understood that this use of the editorial "we" +is merely a modest subterfuge on the part of Professor Lockyer--"have +no regard for them at all simply as ours. Like all scientists worthy the +name, we seek only the truth, and should new facts come along that seem +to antagonize our theory we should welcome them as eagerly as we welcome +all new facts of whatever bearing. But the truth is that no such new +facts have appeared in all these years, but that, on the contrary, the +meteoritic hypothesis has received ever-increasing support from most +unexpected sources, from none more brilliantly or more convincingly than +from this new star in Perseus." And I suspect that as much as this at +least--if not indeed a good deal more--will be freely admitted by every +candid investigator of Sir Norman Lockyer's theory. + + +SIR WILLIAM RAMSAY AND THE NEW GASES + +The seat of Sir William Ramsay's labors is the University College, +London. The college building itself, which is located on Gower Street, +is, like the British Museum, reminiscent or rather frankly duplicatory +in its columned architecture of the classical. Interiorly it is like +so many other European institutions in its relative simplicity of +equipment. One finds, for example, Professor Ramsay and Dr. Travers +generating the hydrogen for their wonderful experiments in an old +beer-cask. Professor Ramsay himself is a tall, rather spare man, just +entering the gray stage of life, with the earnest visage of the scholar, +the keen, piercing eye of the investigator--yet not without a twinkle +that justifies the lineage of the "canny Scot." He is approachable, +affable, genial, full of enthusiasm for his work, yet not taking it with +such undue seriousness as to rob him of human interest--in a word, the +type of a man of science as one would picture him in imagination, and +would hope, with confident expectation, to find him in reality. + +I have said that the equipment of the college is somewhat primitive, but +this must not be taken too comprehensively. Such instances as that +of the beer-cask show, to be sure, an adaptation of means to ends on +economical lines; yet, on the other hand, it should not be forgotten +that the beer-cask serves its purpose admirably; and, in a word, it may +be said that Professor Ramsay's laboratory contains everything that +is needed to equip it fully for the special work to which it has been +dedicated for some years past. In general, it looks like any other +laboratory--glass tubes, Bunsen burners, retorts and jars being in +more or less meaningless tangles; but there are two or three bits of +apparatus pretty sure to attract the eye of the casual visitor which +deserve special mention. One of these is a long, wooden, troughlike +box which extends across the room near the ceiling and is accessible by +means of steps and a platform at one end. Through this boxlike tube the +chief expert in spectroscopy (Dr. Bay-ley) spies on the spectrum of +the gas, and learns some of its innermost secrets. But an even more +mystifying apparatus is an elaborate array of long glass tubes, some of +them carried to the height of several feet, interspersed with cups of +mercury and with thermometers of various sizes and shapes. The technical +scientist would not make much of this description, but neither would an +untechnical observer make much of the apparatus; yet to Dr. Travers, its +inventor, it is capable of revealing such extraordinary things as the +temperature of liquid hydrogen--a temperature far below that at which +the contents of even an alcoholic thermometer are solidified; at which, +indeed, the prime constituents of the air suffer a like fate. The +responsible substance which plays the part of the familiar mercury, or +alcohol, in Dr. Travers's marvellous thermometer is hydrogen gas. +The principle by which it is utilized does not differ, in its rough +essentials, from that of ordinary thermometers, but the details of its +construction are much too intricate to be elaborated here. + +But if you would see the most wonderful things in this laboratory--or +rather, to be quite accurate, I should say, if you would stand in the +presence of the most wonderful things--you must go with Professor +Ramsay to his own private laboratory, and be introduced to some little +test-tubes that stand inverted in cups of mercury decorating a shelf at +one end. You would never notice these tubes of your own accord were +you to browse ever so long about the room. Even when your attention +is called to them you still see nothing remarkable. These are ordinary +test-tubes inverted over ordinary mercury. They contain something, since +the mercury does not rise in them completely, but if that something be +other than ordinary air there is nothing about its appearance, or rather +lack of appearance, to demonstrate it. But your interest will hardly +fail to be arrested when Professor Ramsay, indicating one and another of +these little tubes, says: "Here you see, or fail to see, all the krypton +that has ever been in isolated existence in the world, and here all the +neon, and here, again, all the zenon." + +You will understand, of course, that krypton, neon, and zenon are the +new gases of the atmosphere whose existence no one suspected until +Professor Ramsay ferreted them out a few years ago and isolated them. In +one sense there should be nothing mysterious about substances that every +air-breathing creature on the globe has been imbibing pretty constantly +ever since lungs came into fashion. But in another view the universal +presence of these gases in the air makes it seem all the more wonderful +that they could so long have evaded detection, considering that +chemistry has been a precise science for more than a century. During +that time thousands of chemists have made millions of experiments in the +very midst of these atmospheric gases, yet not one of the experimenters, +until recently, suspected their existence. This proves that these gases +are no ordinary substances--common though they be. Personally I have +examined many scientific exhibits in many lands, but nowhere have I seen +anything that filled my imagination with so many scientific visions as +these little harmless test-tubes at the back of Professor Ramsay's desk. +Perhaps I shall attempt to visualize some of these imaginings before +finishing this paper, but for the moment I wish to speak of the _modus +operandi_ of the discovery of these additions to the list of elements. + +The discovery of argon came about in a rather singular way. Lord +Rayleigh, of the Royal Institution, had noticed in experiments with +nitrogen that when samples of this element were obtained from chemicals, +such samples were uniformly about one per cent, lighter in weight +than similar quantities of nitrogen obtained from the atmosphere. +This discrepancy led him to believe that the atmospheric nitrogen must +contain some impurity. + +Curiously enough, the experiments of Cavendish, the discoverer of +nitrogen--experiments made more than a century ago--had seemed to show +quite conclusively that some gaseous substance different from nitrogen +was to be found mixed with the samples of this gas as he obtained it +from the atmosphere. This conclusion of Cavendish, put forward indeed +but tentatively, had been quite ignored by his successors. Now, +however, it transpired, by experiments made jointly by Lord Rayleigh +and Professor Ramsay, that the conclusion was quite justified, it being +shown presently that there actually exists in every portion of nitrogen, +as extracted from the atmosphere, a certain quantity of another gas, +hitherto unknown, and which now received the name of argon. It will +be recalled with what astonishment the scientific and the unscientific +world alike received the announcement made to the Royal Society in 1895 +of the discovery of argon, and the proof that this hitherto unsuspected +constituent of the atmosphere really constitutes about one per cent, of +the bulk of atmospheric nitrogen, as previously estimated. + +The discovery here on the earth of a substance which Professor Lockyer +had detected as early as 1868 in the sun, and which he had provisionally +named helium, excited almost equal interest; but this element was found +in certain minerals, and not as a constituent of the atmosphere. + +Having discovered so interesting a substance as argon, Professor +Ramsay and his assistants naturally devoted much time and attention to +elucidating the peculiarities of the new substance. In the course of +these studies it became evident to them that the presence of argon alone +did not fully account for all the phenomena they observed in handling +liquefied air, and in 1898 Professor Ramsay was again able to electrify +his audience at the Royal Society by the announcement of the discovery, +in pretty rapid succession, of three other elementary substances as +constituents of the atmosphere, these three being the ones just referred +to--krypton, neon, and zenon. + +It is a really thrilling experience, standing in the presence of the +only portions of these new substances that have been isolated, to hear +Professor Ramsay and Dr. Travers, his chief assistant, tell the story +of the discovery--how they worked more and more eagerly as they found +themselves, so to say, on a "warmer scent," following out this clew +and that until the right one at last brought the chase to a successful +issue. "It was on a Sabbath morning in June, if I remember rightly, +when we finally ran zenon down," says Dr. Travers, with a half smile; +and Professor Ramsay, his eyes twinkling at the recollection of this +very unorthodox procedure, nods assent. "And have you got them all +now?" I queried, after hearing the story. "Yes; we think so," replied +Professor Ramsay. "And I am rather glad of it," he adds, with a half +sigh, "for it was wearisome even though fascinating work." Just how +wearisome it must have been only a professional scientific investigator +can fully comprehend; but the fascination of it all may be comprehended +in some measure by every one who has ever attempted creative work of +whatever grade or in whatever field. + +I have just said that the little test-tubes contain the only bit of +each of the substances named that has ever been isolated. This statement +might lead the untechnical reader to suppose that these substances, once +isolated, have been carefully stored away and jealously guarded, each +in its imprisoning test-tubes. Jealously guarded they have been, to be +sure, but there has not been, by any means, the solitary confinement +that the words might seem to imply. On the contrary, each little whiff +of gas has been subjected to a variety of experiments--made to pass +through torturing-tubes under varying conditions of temperature, and +brought purposely in contact with various other substances, that its +physical and chemical properties might be tested. But in each case the +experiment ended with the return of the substance, as pure as before, to +its proper tube. The precise results of all these experiments have been +communicated to the Royal Society by Professor Ramsay. Most of these +results are of a technical character, hardly appealing to the average +reader. There is one very salient point, however, in regard to which all +the new substances, including argon and helium, agree; and it is that +each of them seems to be, so far as present experiments go, absolutely +devoid of that fundamental chemical property, the power to combine with +other elements. All of them are believed to be monatomic--that is +to say, each of their molecules is composed of a single atom. This, +however, is not an absolutely novel feature as compared with other +terrestrial elements, for the same thing is true, for example, of such a +familiar substance as mercury. But the incapacity to enter into chemical +combinations seems very paradoxical; indeed it is almost like saying +that these are chemical elements which lack the most fundamental of +chemical properties. + +It is this lack of combining power, of course, that explains the +non-discovery of these elements during all these years, for the +usual way of testing an element is to bring it in contact with other +substances under conditions that permit its atoms to combine with +other atoms to the formation of new substances. But in the case of new +elements such experiments as this have not proved possible under any +conditions as yet attained, and reliance must be had upon other physical +tests--such as variation of the bulk of the gas under pressure, and +under varying temperatures, and a study of the critical temperatures +and pressures under which each gas becomes a liquid. The chief reliance, +however, is the spectroscope--the instrument which revealed the presence +of helium in the sun and the stars more than a quarter of a century +before Professor Ramsay ferreted it out as a terrestrial element. +Each whiff of colorless gas in its test-tube interferes with the light +passing through it in such a way that when viewed through a prism it +gives a spectrum of altogether unique lines, which stamp it as krypton, +neon, or zenon as definitely as certain familiar and more tangible +properties stamp the liquid which imprisons it as mercury. + + +QUERIES SUGGESTED BY THE NEW GASES + +Suppose that a few years ago you had asked some chemist, "What are the +constituents of the atmosphere?" He would have responded, with entire +confidence, "Oxygen and nitrogen chiefly, with a certain amount of +water-vapor and of carbonic-acid gas and a trace of ammonia." If +questioned as to the chief properties of these constituents, he would +have replied, with equal facility, that these are among the most +important elements; that oxygen might almost be said to be the +life-giving principle, inasmuch as no air-breathing creature could get +along without it for many moments together; and that nitrogen is equally +important to the organism, though in a different way, inasmuch as it is +not taken up through the lungs. As to the water-vapor, that, of course, +is a compound of oxygen and hydrogen, and no one need be told of its +importance, as every one knows that water makes up the chief bulk of +protoplasm; carbonic-acid gas is also a compound of oxygen, the other +element this time being carbon, and it plays a quite different role in +the economy of the living organism, inasmuch as it is produced by the +breaking down of tissues, and must be constantly exhaled from the lungs +to prevent the poisoning of the organism by its accumulation; while +ammonia, which exists only in infinitesimal quantities in the air, is a +compound of nitrogen and hydrogen, introducing, therefore, no new +element. + +If one studies somewhat attentively the relation which these elements +composing the atmosphere bear to the living organism he cannot fail to +be struck with it; and it would seem a safe inductive reasoning from the +stand-point of the evolutionist that the constituents of the atmosphere +have come to be all-essential to the living organism, precisely because +all their components are universally present. But, on the other hand, +if we consider the matter in the light of these researches regarding the +new gases, it becomes clear that perhaps the last word has not been said +on this subject; for here are four or five other elementary substances +which, if far less abundant than oxygen and nitrogen, are no less widely +distributed and universally present in the atmosphere, yet no one of +which apparently takes any chemical share whatever in ministering to the +needs of the living organism. This surely is an enigma. + +Taking another point of view, let us try to imagine the real status of +these new gases of the air. We think of argon as connected with nitrogen +because in isolation experiments it remains after the oxygen has been +exhausted, but in point of fact there is no such connection between +argon and nitrogen in nature. The argon atom is just as closely in +contact with the oxygen in the atmosphere as with the nitrogen; it +simply repels each indiscriminately. But consider a little further; +the argon atom not only repels all advance on the part of oxygen and +nitrogen, but it equally holds itself aloof from its own particular +kindred atoms. The oxygen or nitrogen atom never rests until it has +sought out a fellow, but the argon atom declines all fellowship. When +the chemist has played his tricks upon it, it finds itself crowded +together with other atoms of the same kind; but lift up the little +test-tube and these scurry off from one another in every direction, each +losing its fellows forever as quickly as possible. + +As one ponders this one is almost disposed to suggest that the atom of +argon (or of krypton, helium, neon, or zenon, for the same thing applies +to each and all of these) seems the most perfect thing known to us in +the world, for it needs no companionship, it is self-sufficing. There +is something sublime about this magnificient isolation, this splendid +self-reliance, this undaunted and undauntable self-sufficiency--these +are traits which the world is wont to ascribe to beings more than +mortal. But let us pause lest we push too far into the old, discredited +territory of metaphysics. + + +PROFESSOR J. J. THOMPSON AND THE NATURE OP ELECTRICITY + +Many fascinating questions suggest themselves in connection with these +strange, new elements--new, of course, only in the sense of human +knowledge--which all these centuries have been about us, yet which have +managed until now to keep themselves as invisible and as intangible as +spirits. Have these celibate atoms remained thus always isolated, taking +no part in world-building? Are they destined throughout the sweep of +time to keep up this celibate existence? And why do these elements alone +refuse all fellowship, while the atoms of all the other seventy-odd +known elements seek out mates under proper conditions with unvarying +avidity? + +It is perhaps not possible fully to answer these questions as yet, but +recent studies in somewhat divergent fields give us suggestive clews to +some of them. I refer in particular to the studies in reference to the +passage of electricity through liquids and gases and to the observations +on radioactivity. The most conspicuous worker in the field of +electricity is Professor J. J. Thompson, who for many years has had +charge of the Cavendish laboratory at Cambridge. In briefly reviewing +certain phases of his work we shall find ourselves brought into contact +with some of the same problems raised by workers in the other fields of +physics, and shall secure some very interesting bits of testimony as to +the solution of questions already outlined. + +The line of observation which has led to the most striking results has +to do, as already suggested, with the conduction of electricity through +liquids and gases. It has long been known that many liquids conduct +electricity with relative facility. More recently it has been observed +that a charge of electricity carried by any liquid bears a curious +relation to the atomic composition of that liquid. If the atom in +question is one of the sort that can combine with only a single other +atom (that is to say, a monovalent atom), each atom conveys a unit +charge, which is spoken of as an ion of electricity. But if a divalent +atom is in question the charge carried is double, and, similarly, a +trivalent atom carries a triple charge. As there are no intermediate +charges it is obvious that here a very close relation is suggested +between electrical units and the atomic units of matter. + +This, however, is only a beginning. Far more interesting are the results +obtained by the study of gases in their relation to the conduction +of electricity. As is well known, gases under ordinary conditions are +nonconductors. But there are various ways in which a gas may be changed +so as to become a conductor; for example, by contact with incandescent +metals or with flame, or by treating with ultra-violet light, with +Rontgen rays, or with the rays of a radio-active substance. Now the +all-important question is as to just what change has taken place in the +gas so treated to make it a conductor of electricity. I cannot go into +details here as to the studies that have been addressed to the answer +of this question, but I will briefly epitomize what, for our present +purpose, are the important results. First and foremost of these is the +fact that a gas thus rendered conductive contains particles that can +be filtered out of it by passing the gas through wool or through water. +These particles are the actual agents of conduction of electricity, +since the gas when filtered ceases to be conductive. But there is +another way in which the particles may be removed--namely, by action +of electricity itself. If the gas be caused to pass between two metal +plates, one of them insulated and attached to an electrometer, a charge +of positive electricity at high potential sent through the other plate +will drive part of the particles against the insulated plate. This +proves that the particles in question are positively electrified. +The amount of the charge which they carry may be measured by the +electrometer. + +The aggregate amount of the electrical charge carried by these minute +particles in the gas being known, it is obvious that could we know the +number of particles involved the simplest calculation would determine +the charge of each particle. Professor Thompson devised a singularly +ingenious method of determining this number. The method was based on +the fact discovered by C. T. R. Wilson that charged particles acted as +nuclei round which small drops of water condense much as dust particles +serve the same purpose. "In dust-free air," says Professor Thompson, +"as Aitken showed, it is very difficult to get a fog when damp air is +cooled, since there are no nuclei for the drops to condense round. If +there are charged particles in dust-free air, however, the fog will be +deposited round these by super-saturation far less than that required to +produce any appreciable fog when no charged particles are present. + +"Thus, in sufficiently supersaturated damp air a cloud is deposited on +these charged particles and they are thus rendered visible. This is the +first step towards counting them. The drops are, however, far too small +and too numerous to be counted directly. We can, however, get their +number indirectly as follows: suppose we have a number of these +particles in dust-free air in a closed vessel, the air being saturated +with water-vapor; suppose now that we produce a sudden expansion of the +air in the vessel; this will cool the air, it will be supersaturated +with vapor, and drops will be deposited round the charged particles. Now +if we know the amount of expansion produced we can calculate the cooling +of the gas, and, therefore, the amount of water deposited. Thus we know +the volume of water in the form of drops, so that if we know the volume +of one drop we can deduce the number of drops. To find the size of a +drop, we make use of the investigations made by Sir George Stokes on the +rate at which small spheres fall through the air. In consequence of +the viscosity of the air small bodies fall exceedingly slowly, and the +smaller they are the slower they fall." * + +Professor Thompson gives us the formula by which Stokes made his +calculation. It is a relatively simple algebraic one, but need not be +repeated here. For us it suffices that with the aid of this formula, +by merely measuring the actual descent of the top of a vapor cloud, +Professor Thompson was able to find the volume of the drops and thence +the number of particles. The number of particles being known, the +charge of electricity carried by each could be determined, as already +suggested. Experiments were made with air, hydrogen, and carbonic acid, +and it was found that the particles had the same charge in all of these +gases. "A strong argument," says Professor Thompson, "in favor of +the atomic character of electricity." When we add that the charge in +question was found to be the same as the unit charge of an ion in a +liquid, it will be seen that the experiment has other points of interest +and suggestiveness. + +Even more interesting in some regards were the results of computation +as to the actual masses of the charged particles in question. Professor +Thompson found that the carrier of a negative charge could have only +about one-thousandth part of the mass of a hydrogen atom, which latter +had been regarded as the smallest mass able to have an independent +existence. Professor Thompson gave the name corpuscle to these units +of negative electricity; they are now more generally termed electrons. +"These corpuscles," he says, "are the same however the electrification +may have risen or wherever they may be found. Negative electricity in a +gas at a low pressure has thus a structure analogous to that of a gas, +the corpuscles taking the place of the molecules. The 'negative electric +fluid,' to use the old notation, resembles the gaseous fluid with a +corpuscular instead of a molecular structure.'" Professor Thompson does +not hesitate to declare that we now "know more about 'electric fluid' +than we know about such fluids as air or water."*3* The results of his +studies lead him, he declares, "to a view of electrification which +has a striking resemblance to that of Franklin's _One Fluid Theory of +Electricity_. Instead of taking, as Franklin did, the electric fluid +to be positive electricity," he says, "we take it to be negative. The +'electric fluid' of Franklin corresponds to an assemblage of corpuscles, +negative electrification being a collection of these corpuscles. The +transference of electrification from one place to another is effected +by the motion of corpuscles from the place where there is a gain of +positive electrification to the place where there is a gain of +negative. A positively electrified body is one that has lost some of its +corpuscles."*4* According to this view, then, electricity is not a form +of energy but a form of matter; or, to be more precise, the electrical +corpuscle is the fundamental structure out of which the atom of matter +is built. This is a quite different view from that scarcely less recent +one which regards electricity as the manifestation of ether strain, +but it must be admitted that the corpuscular theory is supported by a +marvellous array of experimental evidence, though it can perhaps hardly +be claimed that this brings the theory to the plane of demonstration. +But all roads of physical science of late years have seemed to lead +towards the electron, as will be made further manifest when we consider +the phenomena of radio-activity, to which we now turn. + + +RADIO-ACTIVITY + +In 1896, something like a year after the discovery of the X-ray, +Niewenglowski reported to the French Academy of Sciences that the +well-known chemical compound calcium sulphide, when exposed to sunlight, +gave off rays that penetrated black paper. He had made his examinations +of this substance, since, like several others, it was known to exhibit +strong fluorescent or phosphorescent effects when exposed to the cathode +rays, which are known to be closely connected with the X-rays. This +discovery was followed very shortly by confirmatory experiments made by +Becquerel, Troost, and Arnold, and these were followed in turn by the +discovery of Le Bon, made almost simultaneously, that certain bodies +when acted upon by sunlight give out radiations which act upon a +photographic plate. These manifestations, however, are not the effect of +radio-activity, but are probably the effects of short ultra-violet +light waves, and are not produced spontaneously by the substances. The +radiations, or emanations, of the radio-active substances, on the other +hand, are given out spontaneously, pass through substances opaque to +ordinary light, such as metal plates, act upon photographic plates, and +discharge electrified bodies. The substances uranium, thorium, polonium, +radium, and their compounds are radioactive, radium being by far the +most active. + +The first definite discovery of such a radio-active substance was made +by M. Henri Becquerel, in 1896, while making some experiments upon +the peculiar ore pitch-blende. Pitch-blende is a heavy, black, +pitchy-looking mineral, found principally at present in some parts of +Saxony and Bohemia on the Continent, in Cornwall in Great Britain, and +in Colorado in America. It is by no means a recently discovered mineral, +having been for some years the source of uranium and its compounds, +which, on account of their brilliant colors, have been used in +dye-stuffs and some kinds of stained glass. It is a complex mineral, +containing at least eight or ten elements, which can be separated from +it only with great difficulty and by complicated chemical processes. + +Becquerers discovery was brought about by a lucky accident, although, +like so many other apparently accidental scientific discoveries, it was +the outcome of a long series of scientific experiments all trending in +the same direction. He had found that uranium, when exposed to the sun's +rays, appeared to possess the property of absorbing them and of then +acting upon a photographic plate. Since pitch-blende contained uranium, +or uranium salts, he surmised that a somewhat similar result might be +obtained with the ore itself. He therefore prepared a photographic plate +wrapped in black paper, intending to attempt making an impression on the +plate of some metal body interposed between it and the pitch-blende. For +this purpose he had selected a key; but as the day proved to be cloudy +he put the plate, with the key and pitch-blende resting upon it, in +a dark drawer in his desk, and did not return to the experiment for +several days. Upon doing so, however, he developed the plate without +further exposure, when to his astonishment he found that the developed +negative showed a distinct impression of the key. Clearly this was the +manifestation of a property heretofore unknown in any natural substance, +and was strikingly similar to the action of the Roentgen rays. Further +investigations by Lord Kelvin, Beattie, Smolan, and Rutherford confirmed +the fact that, like the Roentgen rays, the uranium rays not only acted +upon the photographic plate but discharged electrified bodies. And what +seemed the more wonderful was the fact that these "Becquerel rays," as +they were now called, emanated spontaneously from the pitch-blende. +But although this action is analogous to the Roentgen rays, at least as +regards its action upon the photographic plate and its influence on +the electric field, its action is extremely feeble in comparison, the +Roentgen rays producing effects in minutes, or even seconds, which +require days of exposure to uranium rays. The discovery of the +radio-active properties of uranium was followed about two years later by +the discovery that thorium, and the minerals containing thorium, +possess properties similar to those of uranium. This discovery was +made independently and at about the same time by Schmidt and Madame +Skaldowska Curie. But the importance of this discovery was soon +completely overshadowed by the discovery of radium by Madame Curie, +working with her husband, Professor Pierre Curie, at the Ecole +Polytechnique in Paris. Madame Curie, stimulated by her own discoveries +and those of the other scientists just referred to, began a series of +examinations upon various substances by numerous complicated methods +to try and find a possible new element, as certain peculiarities of the +substances found in the pitch-blende seemed to indicate the presence of +some hitherto unknown body. The search proved a most difficult one +on account of the peculiar nature of the object in question, but the +tireless enthusiasm of Madame Curie knew nothing of insurmountable +obstacles, and soon drew her husband into the search with her. Her first +discovery was that of the substance polonium--so named by Madame Curie +after her native country, Poland. This proved to be another of the +radio-active substances, differing from any other yet discovered, but +still not the sought-for element. In a short time, however, the two +Curies made the great discovery of the element radium--a substance +which, according to their estimate, is some one million eight hundred +thousand times more radioactive than uranium. The name for this element, +_radium_, was proposed by Madame Curie, who had also suggested the term +"radio-activity." + +The bearing of the discovery of radium and radioactivity upon theories +of the atom and matter will be considered in a moment; first the more +tangible qualities of this wonderful substance may be briefly referred +to. The fact that radio-active emanations traverse all forms of matter +to greater or less depth--that is, pass through wood and iron with +something the same ease that light passes through a window-glass--makes +the subject one of greatest interest; and particularly so as the +demonstration of this fact is so tangible. While the rays given out by +radium cannot, of course, be seen by the unaided eye, the effects of +these rays upon certain substances, which they cause to phosphoresce, +are strikingly shown. One of such substances is the diamond, and a +most striking illustration of the power of radium in penetrating opaque +substances has been made by Mr. George F. Kunz, of the American Museum +of Natural History. Mr. Kunz describes this experiment as follows: + +"Radium bromide of three hundred thousand activity was placed in a +sealed glass tube inside a rubber thermometer-holder, which was tightly +screwed to prevent any emanation of any kind from passing through the +joints. This was placed under a heavy silver tureen fully one-sixteenth +of an inch in thickness; upon this were placed four copper plates, such +as are used for engraving; upon these a heavy graduated measuring-glass +10 cm. in diameter; this was filled with water to a depth of six inches. +A diamond was suspended in the water and immediately phosphoresced. +Whenever the tube of radium was drawn away more than two or three feet +the phosphoresce ceased; whenever it was placed under the tureen the +diamond immediately phosphoresced again. This experiment proves that the +active power of the radium penetrated the following substances: + +"Glass in the form of a tube, sealed at both ends; the rubber +thermometer-holder; silver tureen; four copper plates; a glass vase or +measuring-glass one-quarter of an inch in thickness; three inches of +water. There is no previously known substance or agent, whether it be +even light or electricity, that possesses such wonderfully penetrative +powers."*5* + + +THE NATURE OF EMANATIONS FROM RADIO-ACTIVE BODIES + +What, then, is the nature of these radiations? Are they actually +material particles hurled through the ether? Or are they like light--and +possibly the Roentgen rays--simply undulations in the ether? As yet this +question is an open one, although several of the leading investigators +have postulated tentative hypotheses which at least serve as a working +basis until they are either confirmed or supplanted. On one point, +however, there seems to be unanimity of opinion--there seems to be +little question that there are at least three different kinds of rays +produced by radio-active substances. According to Sir William Crookes, +the first of these are free electrons, or matter in an ultra-gaseous +state, as shown in the cathode stream. These particles are extremely +minute. They carry a negative charge of electricity, and are identified +with the electric corpuscles of Thompson. Rays of the second kind are +comparable in size to the hydrogen atom, and are positively electrified. +These are easily checked by material obstructions, although they render +the air a conductor and affect photographic plates. The third are very +penetrating rays, which are not deflected by electricity and which are +seemingly identical with Roentgen rays. Professor E. Rutherford has +named these rays beta (B), alpha (a), and gamma (v) rays respectively. +Of these the beta rays are deviated strongly by the magnetic field, the +alpha much less so--very slightly, in fact--while the gamma rays are not +affected at all. The action of these three different sets of rays upon +certain substances is not the same, the beta and gamma rays acting +strongly upon barium platinocyanide, but feebly on Sidot's blende, +while the alpha rays act exactly the reverse of this, acting strongly on +Sidot's blende. + +If a surface is coated with Sidot's blende and held near a piece of +radium nitrate, the coated surface begins to glow. If now it is examined +with a lens, brilliant sparks or points can be seen. As the radium is +brought closer and closer these sparks increase in number, until, as Sir +William Crookes says, we seem to be witnessing a bombardment of flying +atoms hurled from the radium against the surface of the blende. A little +instrument called a spinthariscope, devised by Dr. Crookes and on sale +at the instrument and optical-goods shops, may be had for a trifling +sum. It is fitted with a lens focused upon a bit of Sidot's blende and +radium nitrate, and in a dark room shows these beautiful scintillations +"like a shower of stars." A still less expensive but similar device +is now made in the form of a microscopic slide, to be used with the +ordinary lens. + +As we said a moment ago, radium appears to be an elementary substance, +as shown by its spark-spectrum being different from that of any other +known substance--the determinative test as fixed by the International +Chemical Congress. A particle of radium free from impurities should, +therefore, according to the conventional conception of an element, +remain unchanged and unchangeable. If any such change did actually take +place it would mean that the conception of the Daltonian atom as +the ultimate particle of matter is definitively challenged from a new +direction. This is precisely what has taken place. In July of 1903 Sir +William Ramsay and Mr. Soddy, in making some experiments with radium, +saw produced, apparently from radium emanations, another quite different +and distinct substance, the element helium. The report of such a +revolutionary phenomenon was naturally made with scientific caution. +Though the observation seemed to prove the actual transformation of one +element into another, Professor Ramsay himself was by no means ready to +declare the absolute certainty of this. Yet the presumption in favor +of this interpretation of the observed phenomena is very strong; and so +cautious a reasoner as Professor Rutherford has declared recently that +"there can be no doubt that helium is derived from the emanations of +radium in consequence of changes of some kind occurring in it."*6* + +"In order to explain the presence of helium in radium on ordinary +chemical lines," says Professor Rutherford, "it has been suggested that +radium is not a true element, but a molecular compound of helium with +some substance known or unknown. The helium compound gradually breaks +down, giving rise to the helium observed. It is at once obvious that +this postulated helium compound is of an entirely different character to +any other compound previously observed in chemistry. Weight for weight, +it emits during its change an amount of energy at least one million +times greater than any molecular compound known. In addition, it must +be supposed that the rate of breaking up of the helium compound is +independent of great ranges of temperature--a result never before +observed in any molecular change. The helium compound in its breaking +up must give rise to the peculiar radiations and also pass through the +successive radio-active change observed in radium.... On the other +hand, radium, as far as it has been examined, has fulfilled every +test required of an element. It has a well-marked and characteristic +spectrum, and there is no reason to suppose that it is not an element in +the ordinarily accepted sense of the term."*7* + + +THE SOURCE OF ENERGY OF RADIO-ACTIVITY + +In 1903 Messrs. Curie and Laborde*8* made the remarkable announcement +that a crystal of radium is persistently warmer than its surrounding +medium; in other words, that it is perpetually giving out heat without +apparently becoming cooler. At first blush this seemed to contradict the +great physical law of the conservation of energy, but physicists were +soon agreed that a less revolutionary explanation of the phenomenon is +perfectly tenable. The giving off of heat is indeed only an additional +evidence of the dissipation of energy to which the radio-active atom +is subjected. And no one now believes that radio-activity can persist +indefinitely without actually exhausting the substance of the atom. Even +so, the evidence of so great a capacity to give out energy is startling, +and has given rise to various theories (all as yet tentative) in +explanation. Thus J. Perrin*9* has suggested that atoms may consist of +parts not unlike a miniature planetary system, and in the atoms of the +radio-elements the parts more distant from the centre are continually +escaping from the central attraction, thus giving rise to the +radiations. Monsieur and Madame Curie have suggested that the energy may +be borrowed from the surrounding air in some way, the energy lost by +the atom being instantly regained. Pilipo Re,*10* in 1903, advanced the +theory that the various parts of the atom might at first have been free +particles constituting an extremely tenuous nebula. + +These parts gradually becoming collected around condensed centres have +formed what we know as the atoms of elements, the atom thus becoming +like an extinct sun of the solar system. From this point of view the +radio-active atoms represent an intermediate stage between nebulae +and chemical atoms, the process of contraction giving rise to the heat +emissions. + +Lord Kelvin has called attention to the fact that when two pieces of +paper, one white and the other black, are placed in exactly similar +glass vessels of water and exposed to light, the temperature of the +vessel containing the black paper is raised slightly higher than the +other. This suggests the idea that in a similar manner radium may keep +its temperature higher than the surrounding air by the absorption of +other radiations as yet unknown. + +Professor J. J. Thompson believes that the source of energy is in the +atom itself and not external to it. "The reason," he says, "which +induces me to think that the source of the energy is in the atom of +radium itself and not external to it is that the radio-activity of +substances is in all cases in which we have been able to localize it a +transient property. No substance goes on being radio-active very long. +It may be asked, how can this statement be reconciled with the fact +that thorium and radium keep up their activity without any appreciable +falling off with time. The answer to this is that, as Rutherford and +Soddy have shown in the case of thorium, it is only an exceedingly small +fraction of the mass which is at any one time radio-active, and that +this radio-active portion loses its activity in a few hours, and has to +be replaced by a fresh supply from the non-radio-active thorium."*11* + +If Professor Thompson's view be correct, the amount of potential energy +inherent in the atom must be enormous. + + +RADIO-ACTIVITY AND THE STRUCTURE OF THE ATOM + +But whatever the source of the energy displayed by the radio-active +substances, it is pretty generally agreed that the radio-activity of +the radio-elements results in the disruption of their atoms. Since all +substances appear to be radio-active in a greater or less degree, +it would seem that, unless there be a very general distribution +of radio-active atoms throughout all substances, all atoms must be +undergoing disruption. Since the distribution of radio-active matter +throughout the earth is so great, however, it is as yet impossible to +determine whether this may not account for the radio-activity of all +substances. + +As we have just seen, recent evidence seems to point to the cause of the +disruption of radio-active atoms as lying in the atoms themselves. This +view is quite in accord with modern ideas of the instability of certain +atoms. It has been suggested that some atoms may undergo a slower +disintegration without necessarily throwing off part of their systems +with great velocity. It is even possible that all matter may be +undergoing transformation, this transformation tending to simplify +and render more stable the constituents of the earth. The radio-active +bodies, however, are the only ones that have afforded an opportunity for +studying this transformation. In these the rapidity of the change would +be directly proportionate to their radioactivity. Radium, according +to the recent estimate of the Curies, would be disintegrating over +a million times more rapidly than uranium. Since the amount of +transformation occurring in radium in a year amounts to from 1-2000 +to 1-10,000 of the total amount, the time required for the complete +transformation of an atom of uranium would be somewhere between two +billion and ten billion years--figures quite beyond the range of human +comprehension. + +Various hypotheses have been postulated to account for the instability +of the atom. Perhaps the most thinkable of these to persons not +specially trained in dealing with abstruse subjects is that of Professor +Thompson. It has the additional merit, also, of coming from one of the +best-known investigators in this particular field. According to this +hypothesis the atom may be considered as a mass of positively and +negatively charged particles, all in rapid motion, their mutual forces +holding them in equilibrium. In case of a very complex structure of +this kind it is possible to conceive of certain particles acquiring +sufficient kinetic energy to be projected from the system. Or the +constraining forces may be neutralized momentarily, so that the particle +is thrown off at the same velocity that it had acquired at the instant +it is released. The primary cause of this disintegration of the atom +may be due to electro-magnetic radiation causing loss of energy of the +atomic system. + +Sir Oliver Lodge suggests that this instability of the atom may be the +result of the atom's radiation of energy. "Lodge considered the simple +case of a negatively charged electron revolving round an atom of +mass relatively large but having an equal positive charge and held in +equilibrium by electrical forces. This system will radiate energy, and +since the radiation of energy is equivalent to motion in a resisting +medium, the particle tends to move towards the centre and its speed +consequently increases. The rate of radiation of energy will increase +rapidly with the speed of the electron. When the speed of the electron +becomes very nearly equal to the velocity of light, according to Lodge, +the system is unstable. It has been shown that the apparent mass of an +electron increases very rapidly as the speed of light is approached, and +is theoretically infinite at the speed of light. There will be at this +stage a sudden increase of the mass of the revolving atom, and, on the +supposition that this stage can be reached, a consequent disturbance of +the balance of forces holding the system together. Lodge considers it +probable that under these conditions the parts of the system will break +asunder and escape from the sphere of one another's influence. + +"It is probable," adds Rutherford, "that the primary cause of the +disintegration of the atom must be looked for in the 1 ss of energy of +the atomic system due to electro-magnetic radiation."*12* + +Several methods have been devised for testing the amount of heat given +off by radium and its compounds, and for determining its actual rise +in temperature above that of the surrounding atmosphere. One of these +methods is to place some substance, such as barium chloride, in a +calorimeter, noting at what point the mercury remains stationary. Radium +is then introduced, whereupon the mercury in the tube gradually rises, +falling again when the radium is removed. By careful tests it has +been determined that a gram of radium emits about twenty-four hundred +gram-calories in twenty-four hours. On this basis a gram of radium in a +year emits enough energy to dissociate about two hundred and twenty-five +grams of water. + +What seems most remarkable about this constant emission of heat by the +radium atom is that it does not apparently draw upon external sources +for it, but maintains it by the internal energy of the atom itself. This +latent energy must be enormous, but is only manifested when the atom +is breaking up. In this process of disruption many of the particles are +thrown off; but the greater part seem to be stopped in their flight in +the radium itself, so that their energy of motion is manifested in the +form of heat. Thus, if this explanation is correct, the temperature of +the radium is maintained above that of surrounding substances by the +bombardment of its own particles. Since the earth and the atmosphere +contain appreciable quantities of radio-active matter, this must play +a very important part in determining the temperature of the globe--so +important a part, indeed, that all former estimates as to the probable +length of time during which the earth and sun will continue to radiate +heat are invalidated. Such estimates, for example, as that of Lord +Kelvin as to the probable heat-giving life of the sun must now be +multiplied from fifty to five hundred times. + +In like manner the length of time that the earth has been sufficiently +cool to support animal and vegetable life must be re-estimated. Until +the discovery of radium it seemed definitely determined that the earth +was gradually cooling, and would continue to cool, un til, like the +moon, it would become too cold to support any kind of vegetable or +animal life whatever. But recent estimates of the amount of radio-active +matter in the earth and atmosphere, and the amount of heat constantly +given off from this source, seem to indicate that the loss of heat +is (for the moment) about evenly balanced by the heat given out by +radio-active matter. Thus at the beginning of the new century we see +the phenomenon of a single discovery in science completely overturning +certain carefully worked out calculations, although not changing the +great principles involved. It is but the repetition of the revolutionary +changes that occur at intervals in the history of science, a simple +discovery setting at naught some of the most careful calculations of a +generation. + + + + +V. THE MARINE BIOLOGICAL LABORATORY AT NAPLES + + +THE AQUARIUM + +MANY tourists who have gone to Naples within recent years will recall +their visit to the aquarium there among their most pleasant experiences. +It is, indeed, a place worth seeing. Any Neapolitan will direct you to +the beautiful white building which it occupies in the public park close +by the water's side. The park itself, statue-guarded and palm-studded, +is one of the show-places of the city; and the aquarium building, +standing isolated near its centre, is worthy of its surroundings. As +seen from the bay, it gleams white amid the half-tropical foliage, +with the circling rampart of hills, flanked by Vesuvius itself, for +background. And near at hand the picturesque cactus growth scrambling +over the walls gives precisely the necessary finish to the otherwise +rather severe type of the architecture. The ensemble prepares one to be +pleased with whatever the structure may have to show within. + +It prepares one also, though in quite another way, for a surprise; for +when one has crossed the threshold and narrow vestibule, while the gleam +of the outside brightness still glows before his eyes, he is plunged +suddenly into what seems at first glimpse a cavern of Egyptian darkness, +and the contrast is nothing less than startling. To add to the effect, +one sees all about him, near the walls of the cavern, weird forms of +moving creatures, which seem to be floating about lazily in the air, in +grottos which glow with a dim light or sparkle with varied colors. One +is really looking through glass walls into tanks of water filled with +marine life; but both glass and water are so transparent that it is +difficult at first glimpse to realize their presence, unless a stream of +water, with its attendant bubbles, is playing into the tanks. And even +then the effect is most elusive; for the surface of the water, which +you are looking up to from below, mirrors the contents of the tanks so +perfectly that it is difficult to tell where the reality ends and the +image begins, were it not that the duplicated creatures move about with +their backs downward in a scene all topsy-turvy. The effect is most +fantastic. + +More than that, it is most beautiful as well. You are, in effect, at the +bottom of the ocean--or rather, at the bottom of many oceans in one. No +light comes to you except through the grottos about you--grottos haunted +by weird forms of the deep, from graceful to grotesque, from almost +colorless to gaudy-hued. To your dilated pupils the light itself has +the weird glow of unreality. It is all like the wonders of the Arabian +Nights made tangible or like a strange spectacular dream. If one were in +a great diving-bell at the bottom of the veritable ocean he could hardly +feel more detached from the ordinary aerial world of fact. + +As one recovers his senses and begins to take definite note of things +about him he sees that each one of the many grottos has a different set +of occupants, and that not all of the creatures there are as unfamiliar +as at first they seemed. Many of the fishes, for example, and the +lobsters, crabs, and the like, are familiar enough under other +conditions, but even these old acquaintances look strange under these +changed circumstances. But for the rest there are multitudes of forms +that one had never seen or imagined, for the sea hides a myriad of +wonders which we who sail over its surface, and at most glance dimly +a few feet into its depths, hardly dream of. Even though one has seen +these strange creatures "preserved" in museums, he does not know +them, for the alleged preservation there has retained little enough of +essential facies of the real creature, which the dead shell can no more +than vaguely suggest. + +Here, however, we see the real thing. Each creature lives and moves in a +habitat as nearly as may be like that which it haunted when at +liberty, save that tribes that live at enmity with one another are here +separated, so that the active struggle for existence, which plays +so large a part in the wild life of sea as well as land, is not +represented. For the rest the creatures of the deep are at home in these +artificial grottos, and disport themselves as if they desired no other +residence. For the most part they pay no heed whatever to the human +inspectors without their homelike prisons, so one may watch their +activities under the most favorable conditions. + +It is odd to notice how curiously sinuous are all the movements, not +alone of the fish, but of a large proportion of the other forms of +moving life of the waters. The curve, the line of beauty, is the symbol +of their every act; there are no angles in their world. They glide +hither and yon, seemingly without an effort, and always with wavy, +oscillating gracefulness. The acme of this sinuosity of movement is +reached with those long-drawn-out fishes the eels. Of these there are +two gigantic species represented here--the conger, a dark-skinned, +rather ill-favored fellow, and the beautiful Italian eel, with a +velvety, leopard-spotted skin. These creatures are gracefulness itself. +They are ribbon-like in tenuousness, and to casual glance they give the +impression of long, narrow pennants softly waving in a gentle breeze. +The great conger--five or six feet in length--has, indeed, a certain +propensity to extend himself rigidly in a fishlike line and lie +immovable, but the other species is always true to his colors, so to +say--his form is always outlined in curves. + +The eels attract their full share of attention from the visitors, but +there is one family of creatures which easily holds the palm over all +the others in this regard. These are the various representatives of the +great cult of squids and cuttle-fishes. The cuttle-fish proper--who, +of course, is no fish at all--is shaped strangely like a diminutive +elephant, with a filmy, waving membrane along its sides in lieu of legs. +Like the other members of his clan, he can change his color variously. +Sometimes he is of a dull brown, again prettily mottled; then, with +almost kaleidoscopic suddenness, he will assume a garb beautifully +striped in black and white, rivalled by nothing but the coat of the +zebra. The cuttle-fish is a sluggish creature, seeking out the darker +corners of his grotto, and often lying motionless for long periods +together. But not so the little squid. He does not thrive in captivity, +and incessantly wings his way back and forth, with slow, wavy +flappings of his filmy appendages, until he wears himself out and dies +unreconciled. + +In marked contrast with both cuttle-fish and squid is their cousin the +octopus--a creepy, crawly creature, like eight serpents in one--at once +the oddest and the most fascinating creature in the entire aquarium. You +will find a crowd almost always before his grotto watching his curious +antics. Usually slow and deliberate in movement, he yet has capacity +for a certain agility. Now and again he dives off suddenly, head first, +through the water, with the directness if not quite with the speed of an +arrow. A moment later, tired of his flight, he sprawls his eight webbed +legs out in every direction, breaking them seemingly into a thousand +joints, and settles back like an animated parachute awreck. Then +perchance he perches on a rock knowingly, with the appearance of +owl-like wisdom, albeit his head looks surprisingly like a frog's. Anon +he holds his head erect and stretches out his long arms in what is most +palpably a yawn. Then, for pure diversion, he may hold himself +half erect on his umbrella frame of legs and sidle along a sort of +quadrille--a veritable "eight hands in round." + +But all the while he conveys distinctly the impression of a creature to +the last degree blase. Even when a crab is let down into his grotto by +an attendant for the edification of the visitors the octopus seems to +regard it with only lukewarm interest. If he deigns to go in pursuit, +it is with the air of one who says, "Anything to oblige," rather than +of eagerness for a morsel of food. Yet withal, even though unhurried, +he usually falls upon the victim with surprising sureness of aim, +encompassing it in his multiform net. Or perhaps, thinking the game +hardly worth so much effort, he merely reaches out suddenly with one +of his eight arms--each of which is a long-drawn-out hand as well--and +grasps the victim and conveys it to his distensible maw without so much +as changing his attitude. + +All this of the giant octopus--brown and warty and wrinkled and blase. +But the diminutive cousin in the grotto with the jellyfishes is a bird +of quite another feather. Physically he is constructed on the same model +as the other, but his mentality is utterly opposed. No grand roles for +him; his part is comedy. He finds life full of interest. He is satisfied +with himself and with the world. He assumes an aspect of positive +rakishness, and intelligence, so to say, beams from his every limb. All +day long he must be up and doing. For want of better business he will +pursue a shrimp for hours at a time with the zest of a true sportsman. +Now he darts after his intended prey like a fox-hound. Again he resorts +to finesse, and sidles off, with eyes fixed in another direction, like +a master of stratagem. To be sure, he never catches the shrimp--but what +of that? The true sportsman is far removed from the necessity for mere +material profit. I half suspect that little octopus would release the +shrimp if once he caught him, as the true fisherman throws back the +excess of his catch. It is sport, not game, that he covets. + + +THE LABORATORY AND ITS FOUNDER + +When one has made the circuit of the aquarium he will have seen and +marvelled at some hundreds of curious creatures utterly unlike anything +to be found above water. Brightly colored starfishes, beautiful +sea-urchins, strange stationary ascidians, and flower-like sea-anemones, +quaint sea-horses, and filmy, fragile jellyfishes and their multiform +kin--all seem novel and wonderful as one sees them in their native +element. Things that appear to be parts of the rocky or sandy bed of the +grottos startle one by moving about, and thus discovering themselves +as living creatures, simulating their environment for purposes of +protection. Or perhaps what seems to be a giant snail suddenly unfurls +wings from its seeming shell, and goes waving through the water, to the +utter bewilderment of the beholder. Such freaks as this are quite +the rule among the strange tribes of the deep, for the crowding of +population there makes the struggle for existence keen, and necessitates +all manner of subterfuges for the preservation of species. + +Each and every one of the thirty-odd grottos will repay long +observation, even on the part of the most casual visitor, and when one +has seen them all, he will know more at first hand of the method of life +of the creatures of the sea than all the books could teach him. He will +depart fully satisfied, and probably, if he be the usual sight-seer, +he will never suspect that what he has seen is really but an incidental +part of the institution whose building he has entered. Even though he +note casually the inscription "Stazione Zoologica" above the entrance, +he may never suspect that the aquarium he has just visited is only an +adjunct--the popular exhibit, so to speak--of the famous institution +of technical science known to the English-speaking world as the Marine +Biological Laboratory at Naples. Yet such is the fact. The aquarium +seems worthy enough to exist by and for itself. It is a great popular +educator as well as amuser, yet its importance is utterly insignificant +compared with the technical features of the institution of which it is +an adjunct. + +This technical department, the biological laboratory proper, has its +local habitation in the parts of the building not occupied by the +aquarium--parts of which the general public, as a rule, sees nothing. +There is, indeed, little to see that would greatly interest the casual +inspector, for in its outward aspects one laboratory is much like +another, a seeming hodgepodge of water-tanks, glass jars of specimens, +and tables for microscopes. The real status of a laboratory is not +determined by the equipment. + +And yet it will not do to press this assertion too far, for in one sense +it is the equipment of the Naples laboratory that has made it what it +is. Not, however, the equipment in the sense of microscopes and other +working paraphernalia. These, of course, are the best of their kind, but +machinery alone does not make a great institution, any more than +clothes make the man. The all-essential and distinctive equipment of +the laboratory reveals itself in its personnel. In the present case, as +always in a truly great institution of any kind, there is one dominating +personality, one moving spirit. This is Dr. Anton Dohrn, founder of the +laboratory, and still its controller and director, in name and in fact. + +More than twenty-five years ago Dr. Dohrn, then a young man fresh from +the universities of his native Germany, discovered what he felt to be +a real need in the biological world. He was struck with the fact that +nowhere in the world could be found an establishment affording good +opportunities for the study of marine life. Water covers three-fifths of +the earth's surface, as everybody knows, and everywhere this water teems +with life, so that a vast preponderance of the living things of the +globe find their habitat there. Yet the student who might desire to make +special studies of this life would find himself balked at the threshold +for want of opportunity. + +It was no great thing to discover this paucity, which, indeed, fairly +beckoned the discoverer. The great thing was to supply the deficiency, +and this was what Dr. Dohrn determined to do. He selected Naples as the +best location for the laboratory he proposed to found, because of its +climate and its location beside the teeming waters of the Mediterranean. +He organized a laboratory; he called about him a corps of able +assistants; he made the Marine Biological Laboratory at Naples famous, +the Mecca of all biological eyes throughout the world. It was not all +done in a day. It was far enough from being done without opposition and +discouragement; but these are matters of history which Dr. Dohrn now +prefers not to dwell upon. Suffice it that the result aimed at was +finally achieved, and in far greater measure than could at first be +hoped for. + +And from that day till this Naples has been the centre of that branch +of biological inquiry which has for its object the investigation of +problems best studied with material gathered from the sea. And this, +let me hasten to add, includes far more than a mere study of the life +histories of marine animals and plants as such. It includes problems of +cell activity, problems of heredity, life problems of many kinds, having +far wider horizons than the mere question as to how a certain fish or +crustacean lives and moves and has its being. + +Dr. Dohrn's chief technical associates are all Germans, like their +leader, but, like him also, all gifted with a polyglot mastery of +tongues that has stood them in good stead in their intercourse with the +biologists of many nationalities who came to work at the laboratory. I +must not pause to dwell upon the personnel of the staff in general, +but there is one other member who cannot be overlooked even in the most +casual survey of the work of the institution. One might almost as well +forget Dr. Dohrn himself as to overlook Signor Lo Bianco, chief of the +collecting department. Signor Bianco it is who, having expert knowledge +of the haunts and habits of every manner of marine creature, can direct +his fishermen where to find and how to secure whatever rare specimen any +worker at the laboratory may desire. He it is, too, who, by studying old +methods and inventing new ones, has learned how to preserve the delicate +forms for subsequent study in lifelike ensemble that no one else can +quite equal. Signor Bianco it is, in short, who is the indispensable +right-hand man of the institution in all that pertains to its practical +working outside the range of the microscope. Each night Signor Lo Bianco +directs his band of fishermen as to what particular specimens are most +to be sought after next day to meet the needs of the workers in the +laboratory. Before sunrise each day, weather permitting, the little +scattered fleet of boats is far out on the Bay of Naples; for the +surface collecting, which furnishes a large share of the best material, +can be done only at dawn, as the greater part of the creatures thus +secured sink into the retirement of the depths during the day, coming +to the surface to feed only at night. You are not likely to see the +collecting party start out, therefore, but if you choose you may see +them return about nine or ten o'clock by going to the dock not far +from the laboratory. The boats come in singly at about this hour, their +occupants standing up to row, and pushing forward with the oars, after +the awkward Neapolitan fashion. Many of the fishermen are quaint +enough in appearance; some of them have grown old in the service of the +laboratory. The morning's catch is contained in glass jars placed +in baskets especially constructed for the purpose. The baskets have +handles, but these are quite superfluous except to lift them from the +boats, for in the transit to the laboratory the baskets are carried, +as almost everything else is carried in Naples, on the head. To the +novitiate it seems a striking risk to pile baskets of fragile glass and +even more fragile specimens one above another, and attempt to balance +the whole on the head, but nothing could be easier, or seemingly more +secure, for these experts. Arrived at the laboratory, the jars are +turned over to Signer Lo Bianco and his assistants, who sort the +material, and send to each investigator in the workrooms whatever he may +have asked for. + +Of course surface-skimming is not the only method of securing material +for the laboratory. The institution owns a steam-launch named the +_Johannes Mueller_, in honor of the great physiologist, which operates +a powerful dredge for securing all manner of specimens from the +sea-bottom. Then ordinary lines and nets are more or less in requisition +for capturing fish. And in addition to the regular corps of collectors, +every fisherman of the neighborhood has long since learned to bring +to the laboratory all rare specimens of any kind that he may chance to +capture. So in one way and another the institution makes sure of having +in tribute all that the richly peopled waters of the Mediterranean can +offer. And this well-regulated system of collecting, combined with the +richness of the fauna and flora of the Bay of Naples, has no small share +in the success of the marine laboratory. But these, of course, were +factors that Dr. Dohrn took into account from the beginning. + +Indeed, it was precisely with an eye to these important factors that +Naples was selected as the site of the future laboratory in the days +when the project was forming. + +The Bay of Naples is most happily located for the needs of the +zoologist. It is not too far south to exclude the fauna of the temperate +zone, yet far enough south to furnish a habitat for many forms of +life almost tropical in character. It has, in short, a most varied and +abundant fauna. And, on the other hand, the large colony of Neapolitan +fishermen made it certain that skilled collectors would always be at +hand to make available the wealth of material. It requires no technical +education to appreciate the value of this to the original investigator, +particularly to the student of life problems. A skilful worker may do +much with a single specimen, as, for example, Johannes Muller did half a +century ago with the one available specimen of amphioxus, the lowest of +vertebrates, then recently discovered. What Muller learned from that one +specimen seems almost miraculous. But what if he had had a bucketful of +the little boneless creatures at his disposal, as the worker at Naples +now may have any day for the asking? + +When it comes to problems of development, of heredity, a profusion +of material is almost a necessity. But here the creatures of the sea +respond to the call with amazing proficiency. Most of them are, of +course, oviparous, and it is quite the rule for them to deposit their +eggs by hundreds of thousands, by millions even. Everybody knows, since +Darwin taught us, that the average number of offspring of any given +species of animal or plant bears an inverse proportion to the liability +of that species to juvenile fatalities. When, therefore, we find a fish +or a lobster or other pelagic creature depositing innumerable eggs, we +may feel perfectly sure that the vast majority of the eggs themselves, +or the callow creatures that come out of them, will furnish food for +their neighbors at an early day. It is an unkind world into which +the resident of the deep is born. But his adversity is his human +contemporary's gain, and the biologist will hardly be blamed, even by +the most tender-hearted anti-vivisectionist, for availing himself freely +of material which otherwise would probably serve no better purpose than +to appease the appetite of some rapacious fish. + +Their abundance is not the only merit, however, of the eggs of pelagic +creatures, in the eyes of the biologist. By equal good-fortune it +chances that colorless things are at a premium in the sea, since to +escape the eye of your enemy is a prime consideration. So the eggs in +question are usually transparent, and thus, shielded from the vision +of marine enemies, are beautifully adapted for the observation of the +biologist. As a final merit, they are mostly of convenient size for +manipulation under the microscope. For many reasons, then, the marine +egg offers incomparable advantages to the student of cell life, an egg +being the typical cell. And since nowadays the cell is the very focus of +attention in the biological world, the importance of marine laboratories +has been enhanced proportionately. + +But of course not all the work can be done with eggs or with living +specimens of any kind. It is equally important on occasion to examine +the tissues of adult specimens, and for this, as a rule, the tissues +must first be subjected to some preserving and hardening process +preliminary to the cutting of sections for microscopical examination. +This is done simply enough in the case of some organisms, but there is +a large class of filmy, tenuous, fragile creatures in the sea population +of which the jellyfish may be mentioned as familiar examples. Such +creatures, when treated in an ordinary way, by dropping them into +alcohol, shrivel up, coming to resemble nothing in particular, and +ceasing to have any value for the study of normal structures. How to +overcome this difficulty was one of the problems attacked from the +beginning at the Naples laboratory. The chief part of the practical work +of these experiments fell to the share of Signor Lo Bianco. The success +that attended his efforts is remarkable. To-day you may see at the +laboratory all manner of filmy, diaphanous creatures preserved in +alcohol, retaining every jot of their natural contour, and thus offering +unexampled opportunities for study _en masse_, or for being sectioned +for the microscope. The methods by which this surprising result has been +accomplished are naturally different for different creatures; Signor Lo +Bianco has written a book telling how it all has been done. Perhaps the +most important principle involved with a majority of the more tenuous +forms is to stupefy the animal by gradually adding small quantities of +a drug, such as chloral, to the water in which the creature is detained. +When by this means the animal has been rendered so insensible that +it responds very sluggishly to stimuli, it is plunged into a toxic +solution, usually formaline, which kills it so suddenly that its muscles +in their benumbed state have not time to contract. + +Any one who has ever tried to preserve a jellyfish, for example, by +ordinary methods will recall the sorry result, and be prepared to +appreciate Signor Lo Bianco's wonderfully beautiful specimens. +Naturalists have come from all over the world to Naples to learn "just +how" the miracle is accomplished, for it must be understood that the +mere citation of the _modus operandi_ by no means enables the +novitiate to apply it successfully at once. In the case of some of the +long-drawn-out forms of clustered ascidians and the like, the delicacy +of manipulation required to make successful preservations raises the +method as practised at Naples almost to the level of a fine art. It is +a boon to naturalists everywhere that the institution here is able +sometimes to supply other laboratories less favorably situated with +duplicates from its wealth of beautifully preserved specimens. + + +METHODS AND RESULTS + +These, then, are some of the material conditions that have contributed +to make the results of the scientific investigations at the Naples +laboratory notable. But of course, even with a superabundance of +material, discoveries do not make themselves. "Who uses this material?" +is, after all, the vital question. And in this regard the laboratory +at Naples presents, for any one who gets at its heart, so to speak, an +ensemble that is distinctive enough; for the men who work in the light +and airy rooms of the laboratory proper have come for the purpose from +all corners of the civilized globe, and not a few of them are men of +the highest distinction in their various lines of biological science. +A large proportion are professors in colleges and universities of their +various countries; and for the rest there is scarcely one who is not +in some sense master of the biological craft. For it must be understood +that this laboratory at Naples is not intended as a training-school for +the apprentice. It offers in the widest sense a university course in +biology, and that alone. There is no instructor here who shows the +new-comer how to use the microscope, how to utilize the material, how +to go about the business of discovery. The worker who comes to Naples +is supposed to have learned all these things long before. He is +merely asked, then, what class of material he desires, and, this being +furnished him, he is permitted to go his own way unmolested. He may work +much or little, or not at all; he may make epochal discoveries or no +discoveries of any sort, and it will be all one to the management. No +one will ask him, in any event, what he has done or why he has not done +otherwise. In a word, the worker in the laboratory here, while being +supplied with opportunities for study such as he could hardly find +elsewhere, retains all the freedom of his own private laboratory. + +Little wonder, then, that it is regarded as a rare privilege to be +allowed to work in this laboratory. Fortunately, however, it is a +privilege that may be obtained by almost any earnest worker who, having +learned the technique of the craft elsewhere, desires now to prosecute +special original studies in biology. Most of the tables here are leased +in perpetuity, for a fixed sum per annum, by various public or private +institutions of different countries. Thus, for example, America has the +right of use of several tables, the Smithsonian Institution leasing one, +Columbia University another, a woman's league a third, and so on. Any +American desiring to work at Naples should make application to one of +these various sources, stating the exact time when he would like to +go, and if there be a vacancy for that time the properly accredited +applicant is almost sure to receive the privilege he asks for. Failing +in this, however, there is still a court of last appeal in Dr. Dohrn +himself, who may have a few unoccupied tables at his disposal, and who +will surely extend the courtesy of their occupancy, for a reasonable +period, to any proper applicant, come he whence he may. + +Thus it chances that one finds men of all nations working in the Naples +laboratory--biologists from all over Europe, including Russia, from +America, from Australia, from Japan. One finds women also, but these, +I believe, are usually from America. Biologists who at home are at the +head of fully equipped laboratories come here to profit by the wealth +of material, as well as to keep an eye upon the newest methods of their +craft, and to gain the inspiration of contact with other workers in +allied fields. Many of the German university teachers, for example, make +regular pilgrimages to Naples during their vacations, and more than one +of them have made the original investigations here that have given them +an international reputation. + +As to the exact methods of study employed by the individual workers +here, little need be said. In this regard, as in regard to instrumental +equipment, one biological laboratory is necessarily much like another, +and the general conditions of original scientific experiment are pretty +much the same everywhere. What is needed is, first, an appreciation of +the logical bearings of the problem to be solved; and, secondly, the +skill and patience to carry out long lines of experiments, many of which +necessarily lead to no tangible result. The selection of material for +the experiments planned, the watching and cultivating of the living +forms in the laboratory tanks, the cutting of numberless filmy sections +for microscopical examination--these things, variously modified for each +case, make up the work of the laboratory student of general biology. +And just in proportion as the experiments are logically planned and +carefully executed will the results be valuable, even though they be but +negative. Just in proportion as the worker, by inclusion and exclusion, +attains authentic results--results that will bear the test of +repetition--does his reputation as a dependable working biologist become +established. + +The subjects attacked in the marine laboratory first and last are +practically coextensive with the range of general biology, bacteriology +excepted. Naturally enough, the life histories of marine forms of +animals and plants have come in for a full share of attention. But, as I +have already intimated, this zoological work forms only a small part of +the investigations undertaken here, for in the main the workers prefer +to attack those general biological problems which in their broader +outlines apply to all forms of living beings, from highest to lowest. +For example, Dr. Driesch, the well-known Leipzig biologist, spends +several months of each year at the laboratory, and has made here most of +those studies of cell activities with which his name is associated. +The past season he has studied an interesting and important problem of +heredity, endeavoring to ascertain the respective shares of the male and +female parents in the development of the offspring. The subjects of his +experiments have been various species of sea-urchins, but the principles +discovered will doubtless be found to apply to most, or perhaps all, +forms of vertebrate life as well. + +While these studies were under way another developmental problem was +being attacked in a neighboring room of the laboratory by Professor +Kitasato, of the University of Tokio, Japan. The subjects this time were +the embryos of certain fishes, and the investigation had to do with +the development of instructive monstrosities through carefully designed +series of injuries inflicted upon the embryo at various stages of its +development. Meantime another stage of the developmental history of +organic things--this time a microscopical detail regarding the cell +divisions of certain plants--has been studied by Professor Mottier, +of Indiana; while another American botanist, Professor Swingle, of +the Smithsonian Institution, has been going so far afield from +marine subjects as to investigate the very practical subject of the +fertilization of figs as practised by the agriculturists about Naples. + +Even from these few citations it will appear how varied are the lines of +attack of a single biological problem; for here we see, at the hands +of a few workers, a great variety of forms of life--radiates, insects, +vertebrates, low marine plants and high terrestrial ones--made to +contribute to the elucidation of various phases of one general topic, +the all-important subject of heredity. All these studies are conducted +in absolute independence, and to casual inspection they might seem to +have little affinity with one another; yet in reality they all trench +upon the same territory, and each in its own way tends to throw light +upon a topic which, in some of its phases, is of the utmost practical +importance to the human family. It is a long vault from the embryo of +an obscure sea-weed to the well-being of man, yet it may well happen--so +wide in their application are the general life principles--that study of +the one may point a practical moral for the other. + +Indeed, it constantly happens that the student of biology, while +gazing through his microscope, hits upon discoveries that have the most +far-removed implications. Thus a few years ago it was discovered that +when a cell is about to bisect itself and become two cells, its nucleus +undergoes a curious transformation. Within the nuclear substance little +bodies are developed, usually threadlike in form, which take on a deep +stain, and which the biologist calls chromosomes. These chromosomes vary +in number in the cells of different animals, but the number is always +the same for any given species of animal. If one were to group animate +beings in classes according to this very fundamental quality of the +cells he would have some very curious relations established. Thus, under +the heading "creatures whose cells have twenty-four chromosomes," one +would find beings so different as "the mouse, the salamander, the trout, +and the lily," while the sixteen-chromosome group would introduce the +very startling association of the ox, the guinea-pig, the onion, and man +himself. But whatever their number, the chromosomes are always exactly +bisected before the cell divides, one-half being apportioned to each of +the two cells resulting from the division. + +Now the application is this: It was the study of these odd nuclear +structures and their peculiar manouvrings that, in large measure, led +Professor Weismann to his well-known theory of heredity, according +to which the acquired traits of any being are not transmissible to the +offspring. Professor Weismann came to believe that the apportionment +of the nuclear substance, though quantitatively impartial, is sometimes +radically uneven in quality; in particular, that the first bisection +of the egg-cell, which marks the beginning of embryonic development, +produces two cells utterly different in potentiality, the one containing +the "body plasm," which is to develop the main animal structures, the +other encompassing the "germ plasm," by which the racial integrity is +[to be preserved. Throughout the life of the individual, he believed, +this isolation continued; hence the assumed lack of influence of +acquired bodily traits upon the germ plasm and its engendered offspring. +Hence, also, the application of the microscopical discovery to the +deepest questions of human social evolution. + +Every one will recall that this theory, born of the laboratory, made +a tremendous commotion in the outside world. Its application to the +welfare and progress of humanity gave it supreme interest, and polemics +unnumbered were launched in its favor and in its condemnation. Eager +search was made throughout the fields of botany and zoology for new +evidence pro or con. But the definitive answer came finally from the +same field of exploration in which the theory had been originated--the +world of the cell--and the Marine Biological Laboratory was the seat of +the new series of experiments which demonstrated the untenability of the +Weismannian position. Most curious experiments they were, for in effect +they consisted of the making of two or more living creatures out of one, +in the case of beings so highly organized as the sea-urchins, the +little fishlike vertebrate, amphioxus, and even the lower orders of true +fishes. Of course the division of one being to form two is perfectly +familiar in the case of those lowly, single-celled creatures such as the +protozoa and the bacteria, but it seems quite another matter when one +thinks of cutting a fish in two and having two complete living fish +remaining. Yet this is virtually what the biologists did. + +Let me hasten to add that the miraculous feat was not accomplished +with an adult fish. On the contrary, it is found necessary to take the +subject quite at the beginning of its career, when it consists of an +egg-cell in the earliest stages of proliferation. Yet the principle is +quite the same, for the adult organism is, after all, nothing more +than an aggregation of cells resulting from repeated divisions (growth +accompanying) and redivisions of that original egg-cell. Considering +its potentialities, the egg-cell, seemingly, is as much entitled to be +considered an individual as is the developed organism. Yet it transpires +that the biologist has been able so to manipulate a developing egg-cell, +after its bisection, that the two halves fall apart, and that each half +(now become an independent cell) develops into a complete individual, +instead of the half-individual for which it seemed destined. A +strange trick, that, to play with an individual _Ego_, is it not? +The traditional hydra with its reanimating heads was nothing to this +scientific hydra, which, when bisected bodily, rises up calmly as two +whole bodies. + +But even this is not the full measure of the achievement, for it has +been found that in some cases the experiment may be delayed until the +developing egg has made a second bisection, thus reaching the four-cell +stage, when four completely formed individuals emerge from the +dismembered egg. And in the case of certain medusae, success has +attended experiments made at the eight-cell and even at the sixteen-cell +stage of development, the creature which had got thus far on its career +in single blessedness becoming eight or sixteen individuals at the wave +of the enchanted wand--that is to say, the dissecting-needle--of +the biologist. All of which savors of conjury, but is really only +matter-of-fact biological experiment--experiment, however, of which +the implications by no means confine themselves to matters of fact +biological. For clearly the fact that the separated egg-cells grow into +complete individuals shows that Weismann's theory, according to which +one of the cells contained only body plasm, the other only germ plasm, +is quite untenable. Thus the theory of the non-transmissibility of +acquired characters is deprived of its supposed anatomical support and +left quite in the air, to the imminent peril of a school of sociologists +who had built thereon new theories of human progress. Also the question +of the multiplied personalities clearly extends far beyond the field +of the biologist, and must be turned over to the consideration of the +psychologist--if, indeed, it does not fall rather within the scope of +the moralist. + +But though it thus often chances that the biologist, while gazing +stoically through his microscope, may discover things in his microcosm +that bear very closely upon the practical interests of the most +unscientific members of the human family, it would be a mistake to +suppose that it is this class of facts that the worker is particularly +seeking. The truth is that, as a rule, the pure biologist is engaged in +work for the love of it, and nothing is further from his thoughts than +the "practical" bearings or remote implications of what he may discover. +Indeed, many of his most hotly pursued problems seem utterly divorced +from what an outsider would call practical bearings, though, to be +sure, one can never tell just what any new path may lead to. Such, for +example, is the problem which, next to questions of cell activities, +comes in for perhaps as large a share of attention nowadays as any other +one biological topic;--namely, the question as to just which of +the various orders of invertebrate creatures is the type from which +vertebrates were evolved in the past ages--in other words, what +invertebrate creature was the direct ancestor of the vertebrates, +including man. Clearly it can be of very little practical importance to +man of to-day as to just who was his ancestor of several million years +ago. But just as clearly the question has interest, and even the layman +can understand something of the enthusiasm with which the specialist +attacks it. + +As yet, it must be admitted, the question is not decisively answered, +several rival theories contending for supremacy in the case. One of +the most important of these theories had its origin at the Naples +laboratory; indeed, Dr. Dohrn himself is its author. This is the view +that the type of the invertebrate ancestor is the annelid--a form whose +most familiar representative is the earth-worm. The many arguments for +and against accepting the credentials of this unaristocratic ancestor +cannot be dwelt upon here. But it may be consolatory, in view of the +very plebeian character of the earth-worm, to know that various of the +annelids of the sea have a much more aristocratic bearing. Thus the +filmy and delicately beautiful structures that decorate the pleasant +home of the quaint little seahorse in the aquarium--structures having +more the appearance of miniature palm-trees than of animals--are really +annelids. One can view Dr. Dohrn's theory with a certain added measure +of equanimity after he learns this, for the marine annelids are seen, +some of them, to be very beautiful creatures, quite fitted to grace +their distinguished offspring should they make good their ancestral +claims. + +These glimpses will suffice, perhaps, to give at least a general idea of +the manner of thing which the worker at the marine laboratory is seeking +to discover when he interrogates the material that the sea has given +him. In regard to the publication of the results of work done at the +Naples laboratory, the same liberal spirit prevails that actuates the +conduct of the institution from first to last. What the investigator +dis* covers is regarded as his own intellectual property, and he +is absolutely free, so far as the management of this institution is +concerned, to choose his own medium in giving it to the world. He may, +and often does, prefer to make his announcements in periodicals or books +issued in his own country and having no connection whatever with the +Naples laboratory. But, on the other hand, his work being sufficiently +important, he may, if he so desire, find a publisher in the institution +itself, which issues three different series of important publications, +under the editorship of Professor Mayer. + +One of these, entitled _Mittheilungen aus der Zoologische Station +zu Neapel_, permits the author to take his choice among four +languages--German, English, French, or Italian. It is issued +intermittently, as occasion requires. The second set of publications +consists of ponderous monographs upon the fauna and flora of the Gulf +of Naples. These are beautifully illustrated in color, and sometimes a +single volume costs as much as seventeen thousand dollars to issue. Of +course only a fraction of that sum is ever recovered through sale of the +book. The third publication, called _Zoologischen Jahresbericht_, is a +valuable resume of biological literature of all languages, keeping the +worker at the laboratory in touch with the discoveries of investigators +elsewhere. + +The latter end is attained further by the library of the institution, +which is supplied with all the periodicals of interest to the biologist +and with a fine assortment of technical books. The library-room, aside +from its printed contents, is of interest because of its appropriate +mural decorations, and because of the bronze portrait busts of the two +patron saints of the institution, Von Baer and Darwin, which look down +inspiringly upon the reader. + +All in all, then, it would be hard to find a deficiency in the Stazione +Zoologica as an instruement of biological discovery. A long list might be +cited of the revelations first brought to light within its walls. And +yet, as it seems to me, the greatest value of this institution as an +educational factor in science--as a biological lever of progress--does +not depend so much upon the tangible revelations of fact that have come +out of its laboratories as upon other of its influences. Scientific +ideas, like all other forms of human thought, move more or less in +shoals. Very rarely does a great discovery emanate from an isolated +observer. The man who cannot come in contact with other workers in +kindred lines becomes more or less insular, narrow, and unfitted for +progress. Nowadays, of course, the free communication between different +quarters of the globe takes away somewhat from the insularity of any +quarter, and each scientist everywhere knows something of what the +others are doing, through wide-spread publications. But this can never +altogether take the place of personal contact and the inspirational +communication from man to man. Hence it is that a rendezvous, where all +the men of a craft go from time to time and meet their fellows from all +over the world, has an influence for the advancement of the guild +which is enormous and unequivocal, even though difficult of direct +demonstration. + +This feature, then, it seems to me, gives Dr. Dohrn's laboratory its +greatest value as an educational factor, as a moving force in the +biological world. It is true that the new-comer there is likely to be +struck at first with a sense of isolation, and to wonder at the seeming +exclusiveness of the workers, the self-absorption of each and every +one. Outside the management, whom he meets necessarily, no one pays +the slightest attention to him at first, or seems to be aware of his +existence. He is simply assigned to a room or table, told to ask for +what he wants, and left to his own devices. As he walks along the +hallways he sees tacked on the doors the cards of biologists from all +over the world, exposing names with which he has long been familiar. +He understands that the bearers of the names are at work within the +designated rooms, but no one offers to introduce him to them, and +for some time, perhaps, he does not so much as see them, nor would he +recognize them if he did. He feels strange and isolated in the midst of +this stronghold of his profession. + +But soon this feeling leaves him. He begins to meet his fellow-workers +casually here and there--in the hallways, at the distributing-tanks, in +the library. There are no formal gatherings, and there are some workers +who never seem to affiliate at all with the others; but in the long-run, +here as elsewhere, kindred spirits find one another out; and even the +unsocial ones take their share, whether or no, in the indefinable but +very sensible influence of massed numbers. Presently some one suggests +to the new-comer that he join some of the others of a Wednesday or +Saturday evening, at a rendezvous where a number of them meet regularly. +He goes, under escort of his sponsor, and is guided through one of those +narrow, dark, hill-side streets of Naples where he would hardly feel +secure to go alone, to a little wine-shop in what seems a veritable +dungeon--a place which, if a stranger in Naples, he would never even +remotely think of entering. But there he finds his confreres of the +laboratory gathered about a long table, with the most conglomerate +groups of Neapolitans of a seemingly doubtful class at their elbows. +Each biologist has a caraffa of light wine on the table before him, +and all are smoking. And, staid men of science that they are, they are +chattering away on trivial topics with the animation of a company of +school-boys. The stock language is probably German, for this bohemian +gathering is essentially a German institution; but the Germans are +polyglots, and you will hardly find yourself lost in their company, +whatever your native tongue. + +Your companions will tell you that for years the laboratory fraternity +have met twice a week at this homely but hospitable establishment. The +host, honest Dominico Vincenzo Bifulco, will gladly corroborate the +statement by bringing out for inspection a great blank-book in which +successive companies of his guests from the laboratory have scrawled +their names, written epigrams, or made clever sketches. That book will +some day be treasured in the library of a bibliophile, but that will not +be until Bifulco is dead, for while he lives he will never part with it. + +One comes to look upon this bohemian wine-shop as an adjunct of the +laboratory, and to feel that the free-and-easy meetings there are +in their way as important for the progress of science as the private +seances of the individual workers in the laboratory itself. Not because +scientific topics are discussed here, though doubtless that sometimes +happens, but because of that vitalizing influence of the contact of +kindred spirits of which I am speaking, and because this is the one +place where a considerable number of the workers at the laboratory meet +together with regularity. + +The men who enter into such associations go out from them revitalized, +full of the spirit of propaganda. Returned to their own homes, they +agitate the question of organizing marine laboratories there; and it is +largely through the efforts of the graduates, so to say, of the Naples +laboratory that similar institutions have been established all over the +world. + +Thanks largely to the original efforts of Dr. Dohrn, nearly +all civilized countries with a coast-line now have their marine +laboratories. France has half a dozen, two of them under government +control. Russia has two on the Black Sea and one on the French +Mediterranean coast. Great Britain has important stations at St. +Andrews, at Liverpool, and at Plymouth. The Scandinavian peninsula has +also three important stations. Germany shows a paucity by comparison, +which, however, is easily understood when one reflects that the +mother-laboratory at Naples is essentially a German institution despite +its location. + +The American stations are located at Woods' Holl and at Cold Spring +Harbor, on opposite coasts of Long Island Sound. The Japanese station is +an adjunct of Tokio University. For the rest, the minor offspring of +the Naples laboratory are too numerous to be cited here. Nor can I enter +into any details regarding even the more important ones. Each in its way +enters into the same general line of work, varying the details according +to the bent of mind of individual directors and the limitations of +individual resources. But in the broader outlines the aim of all is the +same, and what we have seen at Naples is typical of what is best in all +the others. + + + + +VI. ERNST HAECKEL AND THE NEW ZOOLOGY + + +THE DREAM CITY + +THE train crept on its tortuous way down the picturesque valley of the +little Saale. At last we saw, high above us, on a jutting crag, three +quaint old castles, in one of which, as we knew from our _Baedeker_; +Goethe at one time lived. We were entering the region of traditions. +Soon we knew we should be passing that famous battle-field on which +Napoleon, in 1806, sealed the fate of Germany for a generation. But this +spot, as seen from the car window, bore no emblem to distinguish it, and +before we were quite sure that we had reached it we had in point of fact +passed on, and the train was coming to a stop. "Jena!" called the guard, +and the scramble for "luggage" began, leaving us for the moment no place +for other thoughts than to make sure that all our various parcels were +properly dragged out along with ourselves. For a wonder no Dienstman +appeared to give us aid--showing how unexpected is the arrival of any +wayfarer at this untoward season--and for a moment one seemed in danger +of being reduced to the unheard-of expedient of carrying one's own +satchel. But, fortunately, one is rescued from this most un-German +predicament by the porter of a waiting hotel omnibus, and so at last we +have time to look about us, and to awaken to a realizing sense that we +have reached the land of traditions; that we have come to Mecca; that we +are in the quondam home of Guericke, Fichte, Goethe, Schiller, Oken, and +Gagenbaur; in the present home of Haeckel. + +The first glimpse of a mountain beaming down at us from across the way +was in admirable conformity with our expectations, but for the rest, the +vicinage of the depot presented a most distressing air of modernity. A +cluster of new buildings--some of them yet unfinished--stared back at us +and the mountain with the most barefaced aspect of cosmopolitanism. Was +this, then, Jena, the home of traditions? Or were we entering some Iowa +village, where the first settlers still live who but yesterday banished +the prairie-dog and the buffalo? + +But this disappointment and its ironical promptings were but fleeting. +Five minutes' drive and we were in the true Jena with the real flavor of +mediaeval-ism about us. Here is the hostelry where Luther met the Swiss +students in 1522. There is nothing in that date to suggest our Iowa +village, nor in the aspect of the hostelry itself, thank fortune. And +there rises the spire of the city church, up the hill yonder, which was +aging, as were most of the buildings that still flank it, when Luther +made that memorable visit. America was not discovered, let alone Iowa, +when these structures were erected. Now, sure enough, we are in the +dream city. + +A dream city it truly seems, when one comes to wander through its +narrow, tortuous streets, between time-stained walls, amid its rustic +population. Coming from Berlin, from Dresden, from Leipzig--not to +mention America--one feels as if he had stepped suddenly back two or +three centuries into the past. There are some evidences of modernity +that mar the illusion, to be sure; but the preponderance of the +old-time emblems is sufficient to leave the mind in a delightful glow +of reminiscences. As a whole, the aspect of the central portion of the +village--of the true Jena--cannot greatly have changed since the days +when Luther stopped here on his way to Wittenberg; surely not since +1662, when the mighty young Leibnitz, the Aristotle of Germany, came to +Jena to study under Weigel, the most famous of German mathematicians +of that century. Here and there an old house has been demolished, to be +sure; even now you may see the work of destruction going on, as a +new street is being cut through a time-honored block close to the old +church. But in the main the old thoroughfares run hither and thither, +seemingly at random, as of old, disclosing everywhere at their limits +a sky-line of picturesque gables, and shut in by walls that often are +almost canon-like in narrowness; while the heavy, buttressed doors and +the small, high-placed windows speak of a time when every house partook +of the nature of the fortress. + +The footway of the thoroughfares has no doubt vastly changed, for it is +for the most part paved now--badly enough, to be sure, yet, after +all, paved as no city was in the good old days when garbage filled +the streets and cleanliness was an unknown virtue. The Jena streets of +to-day are very modern in their cleanliness; yet a touch of medievalism +is retained in that the main work of cleaning is done by women. But, for +that matter, it seems to the casual observer as if the bulk of all the +work here were performed by the supposedly weaker sex. Certainly woman +is here the chief beast of burden. In every direction she may be seen, +in rustic garb, struggling cheerily along under the burden of a gigantic +basket strapped at her back. You may see the like anywhere else in +Germany, to be sure, but not often elsewhere in such preponderant +numbers. And scarcely elsewhere does the sight jar so little on one's +New-World sensibilities as in the midst of this mediaeval setting. One +is even able to watch the old women sawing and splitting wood in the +streets here, with no thought of anything but the picturesque-ness of +the incident. + +If one follows a band of basket-laden women, he will find that their +goal is that focal-point of every old-time city, the market-place. There +arrived, he will witness a scene common enough in Europe but hardly to +be duplicated anywhere in America. Hundreds of venders of meat, fish, +vegetables, cloths, and household utensils have their open-air booths +scattered all across the wide space, and other hundreds of purchasers +are there as well. Quaint garbs and quainter faces are everywhere, +and the whole seems quite in keeping with the background of +fifteenth-century houses that hedges it in on every side. Could John the +Magnanimous, who rises up in bronze in the midst of the assembly, come +to life, he would never guess that three and a half centuries have +passed since he fell into his last sleep. + +This same John the Magnanimous it was who founded the institution which +gives Jena its fame and distinguishes it from all the other quaint +hypnotic clusters of houses that nestle similarly here and there in +other picturesque valleys of the Fatherland--I mean, of course, its +world-renowned university. It is but a few minutes' walk from the +market-place, past the home where Schiller once lived and through the +"street" scarcely more than arms'-breadth wide beyond, to the site of +the older buildings of the university. Inornate, prosaic buildings they +are, unrelieved even by the dominant note of picturesqueness; rescued, +however, from all suggestion of the commonplace by the rugged ruins of +the famed "powder-tower" jutting out from the crest of the hill just +above, by the spire of the old church which seems to rise from the +oldest university building itself, and by the mountain peaks that jut up +into view far beyond. + +If you would enter one of the old buildings there is naught to hinder. +Go into one of the lecture-halls which chances at the moment to be +unoccupied, and you will see an array of crude old benches for seats +that look as if they might have been placed there at the very inaugural +of the institution. The boards that serve for desks, if you scan them +closer, you will find scarred all over with the marks of knives, showing +how some hundreds of successive classes of listeners have whiled away +the weary lecture-hours. Not a square inch can you find of the entire +desk surface that is un-scarred. If one would woo a new sensation, he +has but to seat himself on one of these puritanical old benches and +conjure up in imagination the long series of professors that may have +occupied the raised platform in front, recalling the manner of thought +and dogma that each laid down as verity. He of the first series appears +in the garb of the sixteenth century, with mind just eagerly striving to +peer a little way out of the penumbra of the Renaissance. The students +who carve the first gashes in the new desks will learn, if perchance +they listen in intervals of whittling, that this World on which they +live is perhaps not flat, but actually round, like a ball. It is +debatable doctrine, to be sure, but we must not forget that Signor +Columbus, recently dead, found land off to the west which is probably a +part of the Asiatic continent. If the earth be indeed a ball, then the +sun and stars whirl clear around it in twenty-four hours, travelling +thus at an astonishing speed, for the sphere in which they are fastened +is situated hundreds of miles away. The sun must be a really great ball +of fire--perhaps a mile even in diameter. The moon, as is plain to see, +is nearly as large. The stars, of course, are only sparks, though of +great brilliancy. They are fixed in a different sphere from that of the +sun. In still other spheres are the moon, and a small set of large stars +called planets, of which latter there are four, in order that, with the +sun, the moon, and the other stars, there may be made seven orders of +heavenly bodies--seven being, of course, the magic number in accordance +with which the universe is planned. + +This is, in substance, the whole subject of astronomy, as that first +professor must have taught it, even were he the wisest man of his time. +Of the other sciences, except an elementary mathematics, there was +hardly so much as an inkling taught that first class of students. You +will find it appalling, as you muse, to reflect upon the amazing mixture +of utter ignorance and false knowledge which the learned professor of +that day brought to the class-room, and which the "educated" student +carried away along with his degree. The one and the other knew Greek, +Latin, and Bible history and doctrine. Beyond that their minds were +as the minds of babes. Yet no doubt the student who went out from the +University of Jena in the year 1550 thought himself upon the pinnacles +of learning. So he was in his day and age, but could he come to life +to-day, in the full flush of his scholarship, yonder wood-vender, plying +her saw out here in front of the university building, would laugh in +derision at his simplicity and ignorance. So it seems that, after all, +the subjects of John the Magnanimous have changed more than a little +during the three hundred and odd years that John himself, done in +bronze, has been standing out there in the market-place. + + +THE CAREER OF A ZOOLOGIST + +Had one time for it, there would be real interest in noting the steps +by which the mental change in question has been brought about; in +particular to note the share which the successive generations of Jena +professors have taken in the great upward struggle. But we must +not pause for that here. Our real concern, despite the haunting +reminiscences, is not with the Jena of the past, but with the Jena of +to-day; not with ghosts, but with the living personality who has made +the Jena of our generation one of the greatest centres of progress in +human thought in all the world. Jena is Jena to-day not so much because +Guericke and Fichte and Hegel and Schiller and Oken taught here in the +past, as because it has for thirty-eight years been the seat of the +labors of Germany's greatest naturalist, one of the most philosophical +zoologists of any country or any age, Professor Ernst Haeckel. It is of +Professor Haeckel and his work that I chiefly mean to write, and if I +have dwelt somewhat upon Jena itself, it is because this quaint, retired +village has been the theatre of Haeckel's activities all the mature +years of his life, and because the work he has here accomplished could +hardly have been done so well elsewhere; some of it, for reasons I shall +presently mention, could hardly have been done elsewhere at all--at +least in another university. + +It was in 1861 that young Dr. Haeckel came first to Jena as a teacher. +He had made a tentative effort at the practice of medicine in Berlin, +then very gladly had turned from a distasteful pursuit to the field of +pure science. His first love, before he took up the study of medicine, +had been botany, though pictorial art, then as later, competed with +science for his favorable attention. But the influence of his great +teacher, Johannes Mueller, together with his medical studies, had turned +his attention more directly to the animal rather than vegetable life, +and when he left medicine it was to turn explicitly to zoology as a life +study. Here he believed he should find a wider field than in art, which +he loved almost as well, and which, it may be added, he has followed all +his life as a dilettante of much more than amateurish skill. Had he so +elected, Haeckel might have made his mark in art quite as definitely +as he has made it in science. Indeed, even as the case stands, his +draughtsman's skill has been more than a mere recreation to him, for +without his beautiful drawings, often made and reproduced in color, his +classical monographs on various orders of living creatures would have +lacked much of their present value. + +Moreover, quite aside from these merely technical drawings, Professor +Haeckel has made hundreds of paintings purely for recreation and the +love of it, illustrating--and that too often with true artistic feeling +for both form and color--the various lands to which his zoological +quests have carried him, such as Sicily, the Canaries, Egypt, and India. +From India alone, after a four-months' visit, Professor Haeckel brought +back two hundred fair-sized water-colors, a feat which speaks at once +for his love of art and his amazing industry. + +I dwell upon this phase of Professor Haeckel's character and temperament +from the very outset because I wish it constantly to be borne in mind, +in connection with some of the doctrines to be mentioned presently, that +here we have to do with no dry-as-dust scientist, cold and soulless, but +with a broad, versatile, imaginative mind, one that links the scientific +and the artistic temperaments in rarest measure. Charles Darwin, with +whose name the name of Haeckel will always be linked, told with regret +that in his later years he had become so steeped in scientific facts +that he had lost all love for or appreciation of art or music. There has +been no such mental warping and atrophy in the mind of Ernst Haeckel. +Yet there is probably no man living to-day whose mind contains a larger +store of technical scientific facts than his, nor a man who has enriched +zoology with a larger number of new data, the result of direct personal +observation in field or laboratory. + +How large Haeckel's contribution in this last regard has been can be +but vaguely appreciated by running over the long list of his important +publications, though the list includes more than one hundred titles, +unless it is understood that some single titles stand for monographs +of gigantic proportions, which have involved years of labor in the +production. Thus the text alone of the monograph on the radiolarians, +a form of microscopic sea-animalcule (to say nothing of the volume of +plates), is a work of three gigantic volumes, weighing, as Professor +Haeckel laughingly remarks, some thirty pounds, and representing twelve +years of hard labor. This particular monograph, by-the-bye, is written +in English (of which, as of several other languages, Professor Haeckel +is perfect master), and has a history of more than ordinary interest. It +appears that the radiolarians were discovered about a half-century +ago by Johannes Mueller, who made an especial-study of them, which was +uncompleted at the time of his death in 1858. His monograph, describing +the fifty species then known, was published posthumously. Haeckel, +on whom the mantle of the great teacher was to fall, and who had been +Mueller's last pupil, took up the work his revered master had left +unfinished as his own first great original _Arbeit_. He went to Messina +and was delighted to find the sea there replete with radiolarians, of +which he was able to discover one or two new species almost every day, +until he had added one hundred and fifty all told to Mueller's list, or +more than triple the whole number previously known. The description of +these one hundred and fifty new radiolarians constituted Haeckel's first +great contribution to zoology, and won him his place as teacher at Jena +in 1861. + +Henceforth Haeckel was, of course, known as the greatest authority +on this particular order of creatures. For this reason it was that +Professor Murray, the naturalist of the famous expedition which the +British government sent around the world in the ship _Challenger_, +asked Haeckel to work up the radiolarian material that had been gathered +during that voyage. Murray showed Haeckel a little bottle containing +water, with a deposit of seeming clay or mud in the bottom. "That +mud," he said, "was dredged up from the bottom of the ocean, and every +particle of it is the shell of a radiolarian." "Impossible," said +Haeckel. "Yet true," replied Murray, "as the microscope will soon prove +to you." + +So it did, and Professor Haeckel spent twelve years examining that mud +under the microscope, with the result that, before he had done, he had +discovered no fewer than four thousand new species of radiolarians, all +of which, of course, had to be figured, described, and christened. +Think of baptizing four thousand creatures, finding a new, distinct, and +appropriate Latin name for each and every one, and that, too, when the +creatures themselves are of microscopic size, and the difference between +them often so slight that only the expert eye could detect it. Think, +too, of the deadly tedium of labor in detecting these differences, +in sketching them, and in writing out, to the length of three monster +volumes, technical dissertations upon them. + +To the untechnical reader that must seem a deadly, a veritably +mind-sapping task. And such, indeed, it would prove to the average +zoologist. But with the mind of a Haeckel it is far otherwise. To him a +radiolarian, or any other creature, is of interest, not so much on its +own account as for its associations. He sees it not as an individual +but as a link in the scale of organic things, as the bearer of a certain +message of world-history. Thus the radiolarians, insignificant creatures +though they seem, have really taken an extraordinary share in building +up the crust of the earth. The ooze at the bottom of the sea, +which finally becomes metamorphosed into chalk or stone, is but the +aggregation of the shells of dead radiolarians. In the light of such a +role the animalcule takes on a new interest. + +But even greater is the interest that attaches to every creature in +regard to the question of its place in the organic scale of evolution. +What are the homologies of this form and that? What its probable +ancestry? What gaps does it bridge? What can it tell us of the story of +animal creation? These and such like are the questions that have been +ceaselessly before Haeckel's mind in all his studies of zoology. Hence +the rich fountain of philosophical knowledge that has welled up from +what otherwise might have been the most barren of laboratory borings. +Thus from a careful investigation of the sponge Haeckel was led to +his famous gastrula theory, according to which the pouchlike +sponge-animalcule--virtually a stomach without members--is the type of +organism on which all high organisms are built, so to speak--that is, +out of which all have evolved. + +This gastrula theory, now generally accepted, is one of Haeckel's two +great fundamental contributions to the evolution philosophy with the +history of which his life work is so intimately linked. The other +contribution is the theory, even more famous and now equally undisputed, +that every individual organism, in its em-bryological development, +rehearses in slurred but unmistakable epitome the steps of evolution by +which the ancestors of that individual came into racial being. That is +to say, every mammal, for example, originating in an egg stage, when it +is comparable to a protozoon, passes through successive stages when it +is virtually in succession a gastrula, a fish, and an amphibian before +it attains the mammalian status, because its direct ancestors were in +succession, through the long geological ages, protozoons, gastrulae, +fishes, amphibians before the true mammal was evolved. This theory cast +a flood of light into many dark places of the Darwinian philosophy. It +was propounded in 1866 in Professor Haeckel's great work on morphology, +and it has ever since been a guiding principle in his important +philosophical studies. + +It was through this same work on morphology that Haeckel first came +to be universally recognized as the great continental champion of +Darwinism--the Huxley of Germany. Like Huxley, Haeckel had at once made +the logical application of the Darwinian theory to man himself, and he +sought now to trace the exact lineage of the human family as no one had +hitherto attempted to fathom it. Utilizing his wide range of zoological +and anatomical knowledge, he constructed a hypothetical tree of +descent--or, if you prefer, ascent--from the root in a protozoon to +the topmost twig or most recent offshoot, man. From that day till this +Haeckel's persistent labors have been directed towards the perfection of +that genealogical tree. + +This work on morphology was much too technical to reach the general +public, but in 1868 Haeckel prepared, at the instigation of his friend +and confrere Gagenbaur, what was practically a popular abridgment of +the technical work, which was published under the title of _The Natural +History of Creation_. This work created a furor at once. It has been +translated into a dozen languages, and has passed through nine editions +in the original German. Through it the name of Haeckel became almost +a household word the world over, and subject for mingled applause +and opprobrium--applause from the unprejudiced for its great merit; +opprobrium from the bigoted because of the unprecedented candor with +which it followed the Darwinian hypothesis to its logical goal. + +The same complete candor of expression has marked every stage of the +unfolding of Professor Haeckel's philosophical pronouncements. This +fact is the more remarkable because Professor Haeckel is, so far as I am +aware, the only scientist of our generation who has felt at liberty to +announce, absolutely without reserve, the full conclusions to which his +philosophy has carried him, when these conclusions ran counter to the +prevalent prejudices of his time. Some one has said that the German +universities are oases of freedom. The remark is absolutely true of +Jena. It is not true, I believe, in anything like the same degree of any +other German university, or of any other university in the world. One +thing before others that has endeared Jena to Haeckel, and kept him +there in the face of repeated flattering calls to other universities, is +that full liberty of spirit has been accorded him there, as he knew it +would not be accorded elsewhere. "When a man comes into the atmosphere +of Jena," says Professor Haeckel, "he perforce begins to think--there +is no escape from it. And he is free to let his thoughts carry +him whithersoever they honestly may. My beliefs," he added, "are +substantially the beliefs of my colleagues in science everywhere, as I +know from private conversations; but they, unlike myself, are not free +to speak the full truth as they see it. I myself would not be tolerated +elsewhere, as I am well aware. Had I desired to remain in Berlin, for +example, I must have kept silent. But here in Jena one is free." + +And he smiles benignly as he says it. The controversies through which he +has passed and the calumnies of which he has been the target have left +no scars upon this broad, calm spirit. + + +HAECKEL AS MAN AND TEACHER + +It is indeed a delightful experience to meet Professor Haeckel in the +midst of his charming oasis of freedom, his beloved Jena. To reach his +laboratory you walk down a narrow lane, past Schiller's house, and +the garden where Schiller and Goethe used to sit and where now the +new observatory stands. Haeckel's laboratory itself is a simple oblong +building of yellowish brick, standing on a jutting point of land high +above the street-level. Entering it, your eye is first caught by a set +of simple panels in the wall opposite the door bearing six illustrious +names: Aristotle, Linne, Lamarck, Cuvier, Mueller, Darwin--a Greek, +a Swede, two Frenchmen, a German, and an Englishman. Such a list is +significant; it tells of the cosmopolitan spirit that here holds sway. + +The ground-floor of the building is occupied by a lecture-room and by +the zoological collection. The latter is a good working-collection, and +purports to be nothing else. Of course it does not for a moment compare +with the collections of the museums in any large city of Europe or +America, nor indeed is it numerically comparable with many private +collections, or collections of lesser colleges in America. Similarly, +when one mounts the stairs and enters the laboratory proper, he finds a +room of no great dimensions and nowise startling in its appointments. It +is admirably lighted, to be sure, and in all respects suitably equipped +for its purpose, but it is by no means so large or so luxurious as the +average college laboratory of America. Indeed, it is not to be mentioned +in the same breath with the laboratories of a score or two of our +larger colleges. Yet, with Haeckel here, it is unquestionably the finest +laboratory in which to study zoology that exists in the world to-day, or +has existed for the last third of a century. + +Haeckel himself is domiciled, when not instructing his classes, in a +comfortable but plain room across the hall--a room whose windows look +out across the valley of the Saale on an exquisite mountain landscape, +with the clear-cut mountain that Schiller's lines made famous at its +focus. As you enter the room a big, robust man steps quickly forward to +grasp your hand. Six feet or more in height, compactly built, without +corpulence; erect, vigorous, even athletic; with florid complexion and +clear, laughing, light-blue eyes that belie the white hair and whitening +beard; the ensemble personifying at once kindliness and virility, +simplicity and depth, above all, frank, fearless honesty, without a +trace of pose or affectation--such is Ernst Haeckel. There is something +about his simple, frank, earnest, sympathetic, yet robust, masculine +personality that reminds one instinctively, as does his facial contour +also, of Walt Whitman. + +A glance about the room shows you at once that it is a place for study, +and also that it is the room of the most methodical of students. +There are books and papers everywhere, yet not the slightest trace of +disorder. Clearly every book and every parcel of papers has a place, +and is kept in that place. The owner can at any moment lay his hand upon +anything he desires among all these documents. This habit of orderliness +has had no small share, I take it, in contributing to Professor +Haeckel's success in carrying forward many lines of research at the same +time, and carrying all to successful terminations. Then there goes with +it, as a natural accompaniment, a methodical habit of working, +without which no single man could have put behind him the multifarious +accomplishments that stand to Professor Haeckers credit. + +Orderliness is not a more pronounced innate gift with Professor Haeckel +than is the gift of initial energy to undertake and carry on work which +leads to accomplishment--a trait regarding which men, even active men, +so widely differ. But Professor Haeckel holds that whatever his normal +bent in this direction, it was enormously strengthened in boyhood by the +precepts of his mother--from whom, by-the-bye, he chiefly inherits his +talents. "My mother," he says, "would never permit me to be idle for a +moment. If I stood at a window day-dreaming, she would always urge me +to be up and doing. 'Work or play,' she would urge, 'but do not stand +idle.' Through this reiterated admonition, physical activity became a +life-long habit with me, and work almost a necessity of my being. If +I have been able to accomplish my full share of labors, this is the +reason. I am never idle, and I scarcely know the meaning of _ennui_." + +This must not be interpreted as meaning, however, that Professor Haeckel +takes up a task and works at it all day long unceasingly. That is not +the German method of working, and in this regard Professor Haeckel is +a thorough German. "When I was a young man," he says, "I at one time, +thanks to the persuasions of some English friends, became a convert to +the English method of working, and even attempted to introduce it into +Germany. But I soon relinquished it, and lapsed back into our German +method, which I am convinced will produce better results for the average +worker. The essential of this method is the long midday rest, which +enables one late in the afternoon to begin what is virtually a new +day's-work, and carry it out with vigor and without undue fatigue. +Thus I, who am an early riser, begin work at five in summer and six in +winter, after the customary light breakfast of coffee and rolls. I do +not take a second breakfast at ten or eleven, as many Germans do, but +work continuously until one o'clock, when I have dinner. This, with +me, as with all Germans, is the hearty meal of the day. After dinner I +perhaps take a half-hour's nap; then read the newspaper, or chat with my +family for an hour, and perhaps go for a long walk. At about four, like +all Germans, I take my cup of coffee, but without cake or other food. +Then, at four, having had three full hours of brain-rest and diversion, +I am ready to go to work again, and can accomplish four hours more of +work without undue fatigue. At eight I have my rather light supper, and +after that I attempt no further work, giving the evening to reading, +conversation, or other recreation. I do not retire till rather late, as +I require only five or six hours' sleep." + +Such is the method of labor division that enables not Professor Haeckel +only, but a host of other German brain-workers to accomplish enormous +labors, yet to thrive on the accomplishment and to carry the ruggedness +and health of youth far into the decades that are too often with our own +workers given over to decrepitude. Haeckel at sixty-five looks as if he +were good for at least a score of years of further effort. And should he +fulfil the promise of his present rugged-ness, he will do no more than +numbers of his colleagues in German universities have done and are +doing. When one runs over the list of octogenarians, and considers at +the same time the amount of the individual output of the best German +workers, he is led to feel that Professor Haeckel was probably right in +giving up the continuous-day method of labor and reverting to the German +method. + +In addition to the original researches that Professor Haeckel has +carried out, to which I have already made some reference, there has, +of course, been all along another large item of time-consumption to be +charged up to his duties as a teacher. These, to be sure, are somewhat +less exacting in the case of a German university professor than they +are in corresponding positions in England or America. Thus, outside the +hours of teaching, Professor Haeckel has all along been able to find +about eight hours a day for personal, original research. When he told +Professor Huxley so in the days of their early friendship, Huxley +exclaimed: "Then you ought to be the happiest man alive. Why, I can find +at most but two hours a day to use for myself." + +So much for the difference between German methods of teaching, where the +university professor usually confines his contact with the pupils to an +hour's lecture each day, and the English system, according to which the +lecturer is a teacher in other ways as well. Yet it must be added that +in this regard Professor Haeckel is not an orthodox German, for his +contact with his students is by no means confined to the lecture-hour. +Indeed, if one would see him at his best, he must go, not to the +lecture-hall, but to the laboratory proper during the hours when +Professor Haeckel personally presides there, and brings knowledge and +inspiration to the eager band of young dissectors who gather there. It +will perhaps seem strange to the reader to be told that the hours on +which this occurs are from nine till one o'clock of a day which is +perhaps not devoted to class-room exercises in any other school of +Christendom whatever--namely, the Sabbath. It is interesting to reflect +what would be the comment on such a procedure in London, for example, +where the underground railway trains even must stop running during the +hours of morning service. But Jena is not London, and, as Professor +Haeckel says, "In Jena one is free. It pleases us to have our Sabbath +service in our tabernacle of science." + +All questions of time aside, it is a favored body of young men who +occupy the benches in the laboratory during Professor Haeckel's unique +Sunday-morning service. Each student has before him a microscope and a +specimen of the particular animal that is the subject of the morning's +lesson. Let us say that the subject this morning is the crawfish. Then +in addition to the specimens with which the students are provided, and +which each will dissect for himself under the professor's guidance, +there are scattered about the room, on the various tables, all manner +of specimens of allied creatures, such as crabs, lobsters, and the like. +There are dissected specimens also of the crawfish, each preparation +showing a different set of organs, exhibited in preserving fluids. Then +there are charts hung all about the room illustrating on a magnified +scale, by diagram and picture, all phases of the anatomy of the subjects +under discussion. The entire atmosphere of the place this morning smacks +of the crawfish and his allies. + +The session begins with a brief off-hand discussion of the general +characteristics and affinities of the group of arthropoda, of which the +crawfish is a member. Then, perhaps, the professor calls the students +about him and gives a demonstration of the curious phenomena of +hypnotism as applied to the crawfish, through which a living specimen, +when held for a few moments in a constrained attitude, will pass into +a rigid "trance," and remain standing on its head or in any other +grotesque position for an indefinite period, until aroused by a blow +on the table or other shock. Such are some of the little asides, so to +speak, with which the virile teacher enlivens his subject and gives it +broad, human interest. Now each student turns to his microscope and his +individual dissection, and the professor passes from one investigator +to another with comment, suggestion, and criticism; answering questions, +propounding anatomical enigmas for solution--enlivening, vivifying, +inspiring the entire situation. + +As the work proceeds, Professor Haeckel now and again calls the +attention of the entire class to some particular phase of the subject +just passing under their individual observation, and in the most +informal of talks, illustrated on blackboard and chart, clears up +any lurking mysteries of the anatomy, or enlivens the subject with an +incursion into physiology, embryology, or comparative morphology of the +parts under observation. Thus by the close of the session the student +has something far more than a mere first-hand knowledge of the anatomy +of the crawfish--though that in itself were much. He has an insight +also into a half-dozen allied subjects. He has learned to look on the +crawfish as a link in a living chain--a creature with physiological, +psychological, ontological affinities that give it a human interest not +hitherto suspected by the novitiate. And when the entire series of +Sunday-morning "services" has been carried through, one order after +another of the animal kingdom being similarly made tribute, the favored +student has gone far towards the goal of a truly philosophical zoology, +as different from the old-time dry-bones anatomy as the living crawfish +is different from the dead shell which it casts off in its annual +moulting time. + + +THE NEW ZOOLOGY + +What, then, is the essence of this "philosophical zoology" of which +Haeckel is the greatest living exponent and teacher and of which his +pupils are among the most active promoters? In other words, what is the +real status, and the import and meaning, the _raison d'etre_, if you +will, of the science of zoology to-day? + +To clear the ground for an answer to that question, one must glance +backward, say half a century, and note the status of the zoology of that +day, that one may see how utterly the point of view has changed since +then; what a different thing zoology has become in our generation from +what it was, for example, when young Haeckel was a student at Jena back +in the fifties. At that time the science of zoology was a conglomeration +of facts and observations about living things, grouped about a set of +specious and sadly mistaken principles. It was held, following Cuvier, +that the beings of the animal kingdom had been created in accordance +with five preconceived types: the vertebrate, with a spinal column; +the articulate, with jointed body and members, as represented by the +familiar crustaceans and insects; the mollusk, of which the oyster and +the snail are familiar examples; the radiate, with its axially +disposed members, as seen in the starfish; and the low, almost formless +protozoon, most of whose representatives are of microscopic size. Each +of these so-called classes was supposed to stand utterly isolated from +the others, as the embodiment of a distinct and tangible idea. So, too, +of the lesser groups or orders within each class, and of the still more +subordinate groups, named technically families, genera; and, finally, +the individual species. That the grouping of species into these groups +was more or less arbitrary was of course to some extent understood, yet +it was not questioned by the general run of zoologists that a genus, +for example, represented a truly natural group of species that had been +created as variations upon one idea or plan, much as an architect +might make a variety of houses, no one exactly like any other, yet all +conforming to a particular type or genus of architecture--for example, +the Gothic or the Romanesque. That each of the groups defined by the +classifiers had such status as this was the stock doctrine of zoology, +as also that the individual species making up the groups, and hence +the groups themselves, maintained their individual identity absolutely +unaltered from the moment of their creation, throughout all successive +generations, to the end of their racial existence. + +Such being the fundamental conception of zoology, it remained only for +the investigator to study each individual species with an eye to +its affinities with other species, that each might be assigned by a +scientific classification to the particular place in the original scheme +of creation which it was destined to occupy. Once such affinities +had been correctly determined and interpreted for all species, the +zoological classification would be complete for all time. A survey of +the completed schedule of classification would then show at a glance the +details of the preconceived system in accordance with which the members +of the animal kingdom were created, and zoology would be a "finished" +science. + +In the application of this relatively simple scheme, to be sure, no end +of difficulties were encountered. Each higher animal is composed of so +many members and organs, of such diverse variations, that naturalists +could never agree among themselves as to just where a balance of +affinities between resemblances and differences should be struck; +whether, for example, a given species varied so much from the type +species of a genus--say the genus Gothic house--as to belong properly +to an independent genus--say Romanesque house; or whether, on the other +hand, its divergencies were still so outweighed by its resemblances as +to permit of its retention as an aberrant member of genus number one. +Perpetual quibbling over these matters was quite the order of the day, +no two authorities ever agreeing as to details of classification. The +sole point of agreement was that preconceived types were in question--if +only the zoologists could ever determine just what these types were. +Meantime, the student who supposed classifications to be matters of +moment, and who laboriously learned to label the animals and birds +of his acquaintance with an authoritative Latin name, was perpetually +obliged to unlearn what he had acquired, as a new classifier brought new +resources of hair-splitting pursuit of a supposed type or ideal to bear +on the subject. Where, for example, our great ornithologists of the +early part of the century, such as Wilson and Audubon, had classed all +our numerous hawks in a genus falco, later students split the group up +into numerous genera--just how many it is impossible to say, as no two +authorities agreed on that point. Wilson, could he have come back a +generation after his death, would have found himself quite at a loss to +converse with his successors about the birds he knew and loved so +well, using their technical names--though the birds themselves had not +changed. + +Notwithstanding all the differences of opinion about matters of detail, +however, there was, nevertheless, substantial agreement about the +broader outlines of classifications, and it might fairly enough +have been hoped that some day, when longer study had led to finer +discrimination, the mysteries of all the types of creation would +be fathomed. But then, while this hope still seemed far enough from +realization, Charles Darwin came forward with his revolutionizing +doctrine--and the whole time-honored myth of "types" of creation +vanished in thin air. It became clear that the zoologists had been +attempting a task utterly Sisyphean. They had sought to establish +"natural groups" where groups do not exist in nature. They were eagerly +peering after an ideal that had no existence outside their imagination. +Their barriers of words could not be made to conform to barriers of +nature, because in nature there are no barriers. + +What, then, was to be done? Should the whole fabric of classification +be abandoned? Clearly not, since there can be no science without +classification of facts about labelled groupings, however arbitrary. +Classifications then must be retained, perfected; only in future it must +be remembered that any classification must be more or less arbitrary, +and in a sense false; that it is at best only a verbal convenience, not +the embodiment of a final ideal. If, for example, we consider the very +"natural" group of birds commonly called hawks, we are quite justified +in dividing this group into several genera or minor groups, each +composed of several species more like one another than like the members +of other groups of species--that is, of other genera. But in so doing we +must remember that if we could trace the ancestry of our various species +of hawks we should find that in the remote past the differences that now +separate the groups had been less and less marked, and originally +quite non-existent, all the various species having sprung from a common +ancestor. The genera of to-day are cousin-groups, let us say; but the +parents of the existing species were of one brood, brothers and sisters. +And what applies to the minor groups called genera applies also, going +farther into the past, to all larger groups as well, so that in the last +analysis, all existing creatures being really the evolved and modified +descendants of one primordial type, it may be said that all animate +creation is but a single kind. In this broadened view the details of +classification ceased to have the importance once ascribed to them, and +the quibblings of the classifiers seem amusing rather than serious. +Yet the changed point of view left the subject by no means barren of +interest. For if the multitudinous creatures of the living world are +but diversified twig-lets of a great tree of ascent, spread by branching +from a common root, at least it is worth knowing what larger branches +each group of twiglets--representing a genus, let us say--has sprung +from. In particular, since the topmost twig of the tree is represented +by man himself and his nearest relatives, is it of human interest to +inquire just what branches and main stems will be come upon in tracing +back the lineage of this particular offshoot. This attempt had, perhaps, +no vast, vital importance in the utilitarian sense in which these terms +are oftenest used, but at least it had human interest. Important or +otherwise, it was the task that lay open to zoology, and apparently its +only task, so soon as the Darwinian hypothesis had made good its status. +The man who first took this task in hand, and who has most persistently +and wisely followed it, and hence the man who became the recognized +leader in the field of the new zoology, was, as I have already +intimated, Professor Haeckel. His hypothetical tree of man's lineage, +tracing the ancestry of the human family back to the earliest geological +times and the lowest orders of beings, has been familiar now for just +a third of a century. It was at first confessedly only a tentative +genealogy, with many weak limbs and untraced branches. It was perfected +from time to time, as new data came to hand, through studies of +paleontology, of embryology, and of comparative anatomy. It will be of +interest, then, to inquire just what is its status today and to examine +briefly Professor Haeckel's own most recent pronouncement regarding it. + +Perhaps it is not worth our while here to go too far down towards the +root of the genealogical tree to begin our inquiry. So long as it is +admitted that the remote ancestry is grounded in the lowest forms of +organisms, it perhaps does not greatly matter to the average reader that +there are dark places in the lineage during the period when our ancestor +had not yet developed a spinal column--when, in other words, he had not +attained the dignity of the lowest fish. Neither, perhaps, need we +mourn greatly that the exact branch by which our reptilian or amphibian +non-mammalian ancestor became the first and most primitive of mammals is +still hidden in unexplored recesses of early strata. The most patrician +monarch of to-day would not be greatly disturbed as to just who were his +ancestors of the days of the cave-dweller. It is when we come a little +nearer home that the question begins to take on its seemingly personal +significance. Questions of grandparents and great-grandparents concern +the patrician very closely. And so all along, the question that has +interested the average casual investigator of the Darwinian theory +has been the question as to man's immediate ancestor--the parents and +grandparents of our race, so to speak. Hence the linking of the word +"monkey" with the phrase "Darwinian theory" in the popular mind; and +hence, also, the interpretation of the phrase "missing link" in relation +to man's ancestry, as applying only to our ancestor and not to any other +of the gaps in the genealogical chain. + +What, then, is the present status of Haeckel's genealogical tree +regarding man's most direct ancestor? Prom what non-human parent did the +human race directly spring? That is a question that has proved itself of +lasting, vital human interest. It is a question that long was answered +only with an hypothesis, but which Professor Haeckel to-day professes +to be able to answer with a decisive and affirmative citation not of +theories but of facts. In a word, it is claimed that man's immediate +ancestor is now actually upon record, that the much-heralded "missing +link" is missing no longer. The principal single document, so to +speak, on which this claim is based consists of the now famous skull and +thigh-bone which the Dutch surgeon, Dr. Eugene Dubois, discovered in the +year 1891 in the tertiary strata of the island of Java. Tertiary strata, +it should be explained, had never hitherto yielded any fossils bordering +on the human type, but this now famous skeleton was unmistakably akin +to the human. The thigh in particular, taken by itself, would have +been pronounced by any competent anatomist to be of human origin. +Unquestionably the individual who bore it had been accustomed to take +an erect attitude in walking. And yet the skull was far inferior in size +and shape to that of any existing tribe of man--was, indeed, rather of +a simian type, though, on the other hand, of about twice the capacity +of any existing ape. In a word, it seemed clear that the creature whose +part skeleton had been found by Dr. Dubois was of a type intermediate +between the lowest existing man and the highest existing man-apes. It +was, in short, the actual prototype of that hypothetical creature which +Haeckel, in his genealogical tree, had christened _pithecanthropus_, the +ape-man. As such it was christened _Pithecanthropus erectus_, the erect +ape-man. + +Now the discovery of this remarkable form did not make Professor Haeckel +any more certain that some such form had existed than he was thirty +years before when he christened a hypothetical subject with the title +now taken by a tangible claimant. But, after all, there is something +very taking about a prophecy fulfilled, and so the appearance of +_Pithecanthropus erectus_ created no small sensation in the zoological +world. He was hailed by Haeckel and his followers as the veritable +"missing link," and as such gained immediate notoriety. But, on the +other hand, a reactionary party at once attacked him with the most +bitter animadversions, denouncing him as no true ancestor of man with +a bitterness that is hard to understand, considering that the origin of +man from _some_ lower form has long ceased to be matter of controversy. +"_Pithecanthropus_ is at least half an ape," they cried, with the clear +implication of "anything but an ape for an ancestor!" + +I confess I have always found it hard to understand just why this +peculiar aversion should always be held against the unoffending ape +tribe. Why it would not be quite as satisfactory to find one's ancestor +in an ape as in the alternative lines of, for example, the cow, or the +hippopotamus, or the whale, or the dog has always been a mystery. Yet +the fact of this prejudice holds. Probably we dislike the ape because +of the very patency of his human affinities. The poor relation is +objectionable not so much because he is poor as because he is a +relation. So, perhaps, it is not the apeness, so to speak, of the ape +that is objectionable, but rather the human-ness. In any event, the +aversion has been matter of common notoriety ever since the Darwinian +theory became fully accepted; it showed itself now with renewed force +against poor _pithecanthropus_. A half-score of objections were launched +against him. It is needless to rehearse them now, since they were all +met valiantly, and the final verdict saw the new-comer triumphantly +ensconced in man's ancestral halls as the oldest sojourner there who +has any title to be spoken of as "human." He is only half human, to be +sure--a veritable ape-man, as his name implies--but exactly therein lies +his altogether unique distinction. He is the embodiment of that "missing +link" whose nonappearance had hitherto given so much comfort to the +sceptical. + +Perhaps some crumbs of comfort may be found by the reactionists in the +fact that it is not held by Professor Haeckel, or by any other competent +authority, that the link which _pithecanthropus_ supplies welds man +directly with any existing man-ape--with gorilla, chimpanzee, or orang. +It is held that these highest existing apes are side branches, so +to say, of the ancestral tree, who developed, in their several ways, +contemporaneously with our direct ancestors, but are not themselves +directly of the royal line. The existing ape that has clung closest to +the direct ancestral type of our own race, it appears, is the gibbon--a +creature far less objectionable in that role because of the very paucity +of his human characteristics, as revealed to the casual observer. +Gibbon-like fossil apes are known, in strata representing a time some +millions of years antecedent to the epoch of _pithecanthropus_ +even, which are held to be directly of the royal line through which +_pithecanthropus_, and the hypothetical _Homo stupidus_, and the known +_Homo neanderthalensis_, and, lastly, proud _Homo sapiens_ himself have +descended. Thus Professor Haeckel is able to make the affirmation, as he +did recently before the International Zoological Congress in Cambridge, +that man's line of descent is now clearly traced, from a stage back in +the Eocene time when our ancestor was not yet more than half arrived to +the ape's estate, down to the time of true human development. "There no +longer exists," he says, "a 'missing link.' The phyletic continuity +of the primate stem, from the oldest lemurs down to man himself, is an +historical fact." + +It should, perhaps, be added that the force of this rather startling +conclusion rests by no means exclusively upon the finding of +_pithecanthropus_ and the other fossils, nor indeed upon any +paleontological evidence whatever. These, of course, furnish data of +a very tangible and convincing kind; but the evidence in its totality +includes also a host of data from the realms of embryology and +comparative anatomy--data which, as already suggested, enabled Professor +Haeckel to predicate the existence of _pithecanthropus_ long in advance +of his actual discovery. Whether the more remote gaps in the chain of +man's ancestry will be bridged in a manner similarly in accord with +Professor Haeckel's predications, it remains for future discoveries +of zoologist and paleontologist to determine. In any event, the recent +findings have added an increment of glory to that philosophical zoology +of which Professor Haeckel is the greatest living exponent. + +This tracing of genealogies is doubtless the most spectacular feature of +the new zoology, yet it must be clear that the establishment of lines +of evolution is at best merely a preparation for the all-important +question, Why have these creatures, man included, evolved at all? That +question goes to the heart of the new zoological philosophy. A partial +answer was, of course, given by Darwin in his great doctrine of natural +selection. But this doctrine, while explaining the preservation of +favorable variations, made no attempt to account for the variations +themselves. Professor Haeckel's contribution to the subject consisted in +the revival of the doctrine of Lamarck, that individual variations, in +response to environmental influences, are transmitted to the offspring, +and thus furnish the material upon which, applying Darwin's principle, +evolution may proceed. This Lamarck-Haeckel doctrine was under a cloud +for a recent decade, during the brief passing of the Weismannian myth, +but it has now emerged, and stands as the one recognized factor in the +origin of those variations whose cumulative preservation through natural +selection has resulted in the evolution of organic forms. + +But may there not be other factors, as yet unrecognized, that supplement +the Lamarckian and Darwinian principles in bringing about this +marvellous evolution of beings? That, it would seem, is the most vital +question that the philosophical zoology of our generation must hand on +to the twentieth century. For today not even Professor Haeckel himself +can give it answer. + + + + +VII. SOME MEDICAL LABORATORIES AND MEDICAL PROBLEMS + + +THE PASTEUR INSTITUTE + +THE national egotism that characterizes the French mind is not without +its compensations. It leads, for example, to the tangible recognition +of the merits of the great men of the nation and to the promulgation +of their names in many public ways. Thus it would be hard to mention a +truly distinguished Frenchman of the older generations whose name has +not been given to a street in Paris. Of the men of science thus +honored, one recalls off-hand the names of Buffon, Cuvier, Geoffroy +Saint-Hilaire, Pinel, Esquirol, Lamarck, Laplace, Lavoisier, Arago, +Claude Bernard, Broca--indeed, one could readily extend the list +to tiresome dimensions. Moreover, it is a list that is periodically +increased by the addition of new names, as occasion offers, for the +Parisian authorities never hesitate to rechristen a street or a portion +of a street, regardless of former associations. + +One of the most recent additions to this roll of fame is the name of +Pasteur. The boulevard that bears that famous name is situated in a +somewhat out-of-the-way corner of the city, though to reach it one has +but to traverse the relatively short course of the Avenue de Breteuil +from so central a position as the tomb of Napoleon. The Boulevard +Pasteur itself is a not long but very spacious thoroughfare, which +will some day be very beautiful, when the character of its environing +buildings has somewhat changed and its quadruple rows of trees have had +time for development. At present its chief distinction, in the eyes +of most observers, would probably be found in the fact that it is the +location of the famous _fete forain_ at one of the annually recurring +stages of the endless itinerary of that noted function. During the +period of this distinction, which falls in the month of May, the +boulevard becomes transformed into a veritable Coney Island of +merry-go-rounds, shooting-galleries, ginger-bread booths, and clap-trap +side-shows, to the endless delight of throngs of pleasure-seekers. There +is no sight in all Paris worthier inspection for the foreigner than the +Boulevard Pasteur offers at this season, for one gains a deep insight +into the psychology of a people through observation of the infantile +delight with which the adult population here throws itself into the +spirit of amusements which with other nations are for the most part +reserved for school-children. Only a race either in childhood or +senescence, it would seem, could thus give itself over with undisguised +delight to the enchantments of wooden horses, cattle, cats, and pigs; to +the catching of wooden fish with hooks; to the shooting at targets that +one could almost touch with the gun-muzzle, and to the grave observation +of sideshow performances that would excite the risibilities of the most +unsophisticated audience that could be found in the Mississippi Valley. + +As we move among this light-hearted and lightheaded throng we shall +scarcely escape a feeling of good-humored contempt for what seems an +inferior race. It will be wholesome, therefore, for us to turn aside +from the boulevard into the Rue Dotot, which leads from it near its +centre, and walk a few hundred yards away from the pleasure-seekers, +where an evidence of a quite different and a no less characteristic +phase of the national psychology will be before us. For here, within +easy sound of the jangling discords of the organs that keep time for the +march of the _cheveaux de bois_, rises up a building that is in a sense +the monument of a man who was brother in blood and in sentiment to the +revellers we have just left in the boulevard, yet whose career stamped +him as one of the greatest men of genius of any race or any time. That +man was Louis Pasteur. The building before us is the famous institute +that bears his name. + +In itself this building is a simple and unimposing structure, yet of +pleasing contour. It is as well placed as the surroundings permit, on a +grassed terrace, a little back from the street, where a high iron fence +guards it and gives it a degree of seclusion. There are other buildings +visible in the rear, which, as one learns on entering, are laboratories +and the like, where the rabbits and guinea-pigs and dogs that are so +essential to the work of the laboratory are kept. On the terrace +in front is a bronze statue of a boy struggling with a rabid dog--a +reminder of the particular labor of the master-worker which led directly +to the foundation of the institution. It will be remembered that it +was primarily to give Pasteur a wider opportunity to apply his newly +discovered treatment for the prevention of rabies that the subscription +was undertaken which led finally to the erection of the buildings before +us and brought the Pasteur Institute in its present form into being. +Of the other aims and objects of the institution I shall speak more at +length in a moment. + +I have just said that the building before us is in effect the monument +of the great savant. This is true in a somewhat more literal sense than +might be supposed, for the body of Pasteur rests in a crypt at its base. +The personal labors of the great discoverer were practically ended at +the time when the institute was opened in 1888, on which occasion, +as will be remembered, the scientific representatives of all nations +gathered in Paris to do honor to the greatest Frenchman of his +generation. He was spared to the world, however, for seven years more, +during which time he fully organized the work of the institution along +the lines it has since followed, and was, of course, the animating +spirit of all the labors undertaken there by his devoted students and +assistants. He is the animating spirit of the institution still, and it +is fitting that his body should rest in the worthy mausoleum within the +walls of that building whose erection was the tangible culmination +of his life labors. The sarcophagus is a shrine within this temple of +science which will serve to stimulate generations of workers here to +walk worthily in the footsteps of the great founder of the institution. +For he must be an unimaginative person indeed who, passing beneath that +arch bearing the simple inscription "Ici Repose Pasteur," could descend +into the simple but impressive mausoleum and stand beside the massive +granite sarcophagus without feeling the same kind of mental uplift which +comes from contact with a great and noble personality. The pretentious +tomb of Galileo in the nave of Santa Croce at Florence, and the crowded +resting-place of Newton and Darwin in Westminster Abbey, have no such +impressiveness as this solitary vault where rests the body of Pasteur, +isolated in death as the mightier spirits must always be in life. + + +AIMS AND OBJECTS OF THE PASTEUR INSTITUTE + +If one chances to come to the institute in the later hours of the +morning he will perhaps be surprised to find a motley company of men, +women, and children, apparently of many nationalities and from varied +walks of life, gathered about one of the entrances or sauntering near +by. These are the most direct beneficiaries of the institution, the +unfortunate victims of the bites of rabid dogs, who have come here to +take the treatment which alone can give them immunity from the terrible +consequences of that mishap. Rabies, or hydrophobia as it is more +commonly termed with us, is well known to be an absolutely fatal malady, +there being no case on record of recovery from the disease once fully +established. Even the treatment which Pasteur developed and which is +here carried out cannot avail to save the victim in whom the active +symptoms of the malady are actually present. But, fortunately, the +disease is peculiarly slow in its onset, sometimes not manifesting +itself for weeks or months after the inoculation; and this delay, which +formerly was to the patient a period of fearful doubt and anxiety, now +suffices, happily, for the application of the protective inoculations +which enable the person otherwise doomed to resist the poison and go +unscathed. Thus it is that the persons who gather here each day to the +number of fifty, or even one hundred, have the appearance of and the +feelings of average health, though a large proportion of them bear in +their systems, on arrival, the germs of a disease that would bring them +speedily to a terrible end were it not that the genius of Pasteur had +found a way to give them immunity. The number of persons who have been +given the anti-rabic treatment here is more than twenty-five thousand. +To have given safety to such an army of unfortunates is, indeed, enough +merit for any single institution; but it must not be supposed that this +record is by any manner of means the full measure of the benefits which +the Institut Pasteur has conferred upon humanity. In point of fact, the +preparation and use of the anti-rabic serum is only one of many aims +of the institution, whose full scope is as wide as the entire domain of +contagious diseases. Pasteur's personal discoveries had demonstrated +the relation of certain lower organisms, notably the bacteria, to the +contagious diseases, and had shown the possibility of giving immunity +from certain of these diseases through the use of cultures of the +noxious bacteria themselves. He believed that these methods could be +extended and developed until all the contagious diseases, which hitherto +have accounted for so startling a proportion of all deaths, were brought +within the control of medical science. His deepest thought in founding +the institute was to supply a tangible seat of operations for this +attempted conquest, where the brilliant assistants he had gathered about +him, and their successors in turn, might take a share in this great +struggle, unhampered by the material drawbacks which so often confront +the would-be worker in science. + +He desired also that the institution should be a centre of education +along the lines of its work, adding thus an indirect influence to the +score of its direct achievements. In both these regards the institution +has been and continues to be worthy of its founder. The Pasteur +Institute is in effect a school of bacteriology, where each of the +professors is at once a teacher and a brilliant investigator. The chief +courses of instruction consist of two series each year of lectures and +laboratory demonstrations on topics within the field of bacteriology. +These courses, at which all the regular staff of the institution assist +more or less, are open to physicians and other competent students +regardless of nationality, and they suffice to inculcate the principles +of bacteriology to a large band of seekers each year. + +But more important, perhaps, than this form of educational influence is +the impetus given by the institute to the researches of a small, select +band of investigators who have taken up bacteriology for a life work, +and who come here to perfect themselves in the final niceties of the +technique of a most difficult profession. Thus such men as Calmette, +the discoverer of the serum treatment of serpent-poisoning, and Yersin, +famous for his researches in the prevention and cure of cholera by +inoculation, are "graduates" of the Pasteur Institute. Indeed, almost +all the chief laborers in this field in the world to-day, including the +directors of practically all the daughter institutes bearing the same +name that are now scattered all over the world, have had at least a +share of their training in the mother institute here in Paris. + +Of the work of the men who form the regular staff of the Pasteur +Institute only a few words need be said here. Doctors Roux, Grancher, +Metchnikoff, and Chamberland all had the privilege of sharing Pasteur's +labors during the later years of the master's life, and each of them is +a worthy follower of the beloved leader and at the same time a brilliant +original investigator.*1* Roux is known everywhere in connection with +the serum treatment of diphtheria, which he was so largely instrumental +in developing. Grancher directs the anti-rabic department and allied +fields. Metchnikoff, a Russian by birth and Parisian by adoption, is +famous as the author of the theory that the white blood-corpuscles of +the blood are the efficient agents in combating bacteria. Chamberland +directs the field of practical bacteriology in its applications to +hygiene, including the department in which protective serums are +developed for the prevention of various diseases of domesticated +animals, notably swine fever and anthrax. About one million sheep and +half as many cattle are annually given immunity from anthrax by the +serum here produced. + +Of the patient and unremitting toil demanded of the investigator in +this realm of the infinitely little; of the skill in manipulation, the +fertility of resource, the scrupulous exactness of experiment that +are absolutely prerequisite to success; of the dangers that attend +investigations which deal with noxious germs, every one who knows +anything of the subject has some conception, but those alone can have +full comprehension who have themselves attempted to follow the devious +and delicate pathways of bacteriology. But the goals to which these +pathways lead have a tangibility that give them a vital interest for all +the world. The hopes and expectations of bacteriology halt at nothing +short of the ultimate extirpation of contagious diseases. The way to +that goal is long and hard, yet in time it will be made passable. And +in our generation there is no company of men who are doing more +towards that end than the staff of that most famous of bacteriological +laboratories the Pasteur Institute. + + +THE VIRCHOW INSTITUTE OF PATHOLOGY + +Even were the contagious diseases well in hand, there would still +remain a sufficient coterie of maladies whose origin is not due to the +influence of living germs. There are, for example, many diseases of the +digestive, nutritive, and excretory systems, of the heart and arteries, +of the brain and nerves, and various less clearly localized abnormal +conditions, that owe their origin to inherent defects of the +organism, or to various indiscretions of food or drink, to unhygienic +surroundings, to material injuries, or to other forms of environmental +stress quite dissociated from the action of bacteria. It is true that +one would need to use extreme care nowadays in defining more exactly the +diseases that thus lie without the field of the bacteriologist, as that +prying individual seems prone to claim almost everything within sight, +and to justify his claim with the microscope; but after that instrument +has done its best or worst, there will still remain a fair contingent +of maladies that cannot fairly be brought within the domain of the +ever-present "germ." On the other hand, all germ diseases have of course +their particular effects upon the system, bringing their results within +the scope of the pathologist. Thus while the bacteriologist has no +concern directly with any disease that is not of bacterial origin, the +pathologist has a direct interest in every form of disease whatever; +in other words, bacteriology, properly considered, is only a special +department of pathology, just as pathology itself is only a special +department of general medicine. + +Whichever way one turns in science, subjects are always found thus +dovetailing into one another and refusing to be sharply outlined. +Nevertheless, here as elsewhere, there are theoretical bounds that +suffice for purposes of definition, if not very rigidly lived up to in +practice; and we are justified in thinking of the pathologist (perhaps +I should say the pathological anatomist) as the investigator of disease +who is directly concerned with effects rather than with causes, who aims +directly at the diseased tissue itself and reasons only secondarily +to the causes. His problem is: given a certain disease (if I may be +permitted this personified form of expression), to find what tissues of +the body are changed by it from the normal and in what manner changed. + +It requires but a moment's reflection to make it clear that a certain +crude insight into the solution of this problem, as regards all common +diseases, must have been the common knowledge of medical men since +the earliest times. Thus not even medical knowledge was needed to +demonstrate that the tissues of an in: flamed part become red and +swollen; and numerous other changes of diseased tissues are almost +equally patent. But this species of knowledge, based on microscopic +inspection, was very vague and untrustworthy, and it was only after the +advent of the perfected microscope, some three-quarters of a century +ago, that pathological anatomy began to have any proper claim to +scientific rank. Indeed, it was not until about the year 1865 that the +real clew was discovered which gave the same impetus to pathology that +the demonstration of the germ theory of disease gave at about the same +time to etiology, or the study of causes of disease. This clew consisted +of the final demonstration that all organic action is in the last resort +a question of cellular activities, and, specifically, that all abnormal +changes in any tissues of the body, due to whatever disease, can consist +of nothing more than the destruction, or the proliferation, or the +alteration of the cells that compose that tissue. + +That seems a simple enough proposition nowadays, but it was at once +revolutionary and inspiring in the day of its original enunciation some +forty years ago. The man who had made the discovery was a young German +physician, professor in the University of Freiburg, by name Rudolph +Virchow. The discovery made him famous, and from that day to this the +name of Virchow has held somewhat the same position in the world +of pathology that the name of Pasteur occupied in the realm of +bacteriology. Virchow was called presently to a professorship in the +University of Berlin. In connection with this chair he established his +famous Institute of Pathology, which has been the Mecca of all students +of pathology ever since. He did a host of other notable things as well, +among others, entering the field of politics, and becoming a recognized +leader there no less than in science. Indeed, it seemed during the later +decades of his life as if one encountered Virchow in whatever direction +one turned in Berlin, and one feels that it was not without reason that +his compatriots spoke of him as "the man who knows everything." To the +end he retained all the alertness of intellect and the energy of body +that had made him what he was. One found him at an early hour in the +morning attending to the routine of his hospital duties, his lectures, +and clinical demonstrations. These finished, he rushed off, perhaps +to his parliamentary duties; thence to a meeting of the Academy of +Sciences, or to preside at the Academy of Medicine or at some other +scientific gathering. And in intervals of these diversified pursuits he +was besieged ever by a host of private callers, who sought his opinion, +his advice, his influence in some matter of practical politics, of +statecraft, or of science, or who, perhaps, had merely come the length +of the continent that they might grasp the hand of the "father of +pathology." + +In whatever capacity one sought him out, provided the seeking were not +too presumptuous, one was sure to find the great savant approachable, +courteous, even cordial. A man of multifarious affairs, he impressed +one as having abundance of time for them all, and to spare. There is a +leisureliness about the seeming habit of existence on the Continent that +does not pertain in America, and one felt the flavor of it quite as much +in the presence of this great worker as among those people who from +our stand-point seem never really to work at all. This is to a certain +extent explained if one visited Virchow in his home, and found to his +astonishment that the world-renowned physician, statesman, pathologist, +anthropologist was domiciled in a little apartment of the most modest +equipment, up two flights, in a house of most unpretentious character. +Everything was entirely respectable, altogether comfortable, to be sure; +but it was a grade of living which a man of corresponding position in +America could not hold to without finding himself quite out of step with +his confreres and the subject of endless comment. But in this city +of universal apartment-house occupancy and relatively low average of +display in living it is quite otherwise. Virchow lived on the same +plane, generally speaking, with the other scientists of Europe; it is +only from the American standpoint that there is any seeming disparity +between his fame and his material station in life; nor do I claim this +as a merit of the American stand-point. + +Be that as it may, however, our present concern lies not with these +matters, but with Virchow the pathologist and teacher. To see the +great scientist at his best in this role, it was necessary to visit the +Institute of Pathology on a Thursday morning at the hour of nine. On +the morning of our visit we found the students already assembled and +gathered in clusters all about the room, examining specimens of morbid +anatomy, under guidance of various laboratory assistants. This was +to give them a general familiarity with the appearances of the +disease-products that would be described to them in the ensuing lecture. +But what is most striking about the room was the very unique method of +arrangement of the desk or table on which the specimens rested. It +was virtually a long-drawn-out series of desks winding back and forth +throughout the entire room, but all united into one, so that a specimen +passed along the table from end to end will make a zigzag tour of the +room, passing finally before each person in the entire audience. To +facilitate such transit, there was a little iron railway all along the +centre of the table, with miniature turn-tables at the corners, along +which microscopes, with adjusted specimens for examination, might be +conveyed without danger of maladjustment or injury. This may seem a +small detail, but it is really an important auxiliary in the teaching +by demonstration with specimens for which this room was peculiarly +intended. The ordinary lectures of Professor Virchow were held in a +neighboring amphitheatre of conventional type. + +Of a sudden there was a hush in the hum of voices, as a little, thin, +frail-seeming man entered and stepped briskly to the front of the +room and upon the low platform before the blackboard in the corner. A +moment's pause for the students to take their places, and the lecturer, +who of course was Virchow himself, began, in a clear, conversational +voice, to discourse on the topic of the day, which chanced to be the +formation of clots in blood-vessels. There was no particular attempt at +oratory; rather the lecturer proceeded as if talking man to man, with +no thought but to make his meaning perfectly clear. He began at once +putting specimens in circulation, as supplied on his demand by his +assistants from a rather grewsome-looking collection before him. Now +he paused to chaff the assistant who was making the labels, poking +good-humored jokes at his awkwardness, but with no trace of sting. Again +he became animated, his voice raised a little, his speech more vehement, +as he advanced his own views on some contested theory or refuted the +objections that some opponent had urged against him, always, however, +with a smile lurking about his eyes or openly showing on his lips. + +Constantly the lecturer turned to the blackboard to illustrate with +colored, crayons such points of his discourse as the actual specimens in +circulation might leave obscure. Everything must be made plain to every +hearer or he would not be satisfied. One can but contrast such teaching +as this with the lectures of the average German professor, who seems not +to concern himself in the least as to whether anything is understood by +any one. But Virchow had the spirit of the true teacher. He had the air +of loving his task, old story as it was to him. Most of his auditors +were mere students, yet he appealed to them as earnestly as if they +were associates and equals. He seemed to try to put himself on their +level--to make his thought near to them. Physically he was near to them +as he talked, the platform on which he stood being but a few inches +in height, and such physical nearness conduces to a familiarity of +discourse that is best fitted for placing lecturer and hearers _en +rapport_. All in all, appealing as it does almost equally to ear and +eye, it is a type of what a lecturer should be. Not a student there but +went away with an added fund of information, which is far more than can +be said of most of the lectures in a German university. + +Needless to say, there are other departments to the Institute of +Pathology. There are collections of beautifully preserved specimens for +examination; rooms for practical experimentation in all phases of the +subject, the chemical side included; but these are not very different +from the similar departments of similar institutions everywhere. What +was unique and characteristic about this institution was the personality +of the director. Now he is gone, but his influence will not soon be +forgotten. The pupils of a great teacher are sure to carry forward the +work somewhat in the spirit of the master for at least a generation. + + +THE BERLIN INSTITUTE OP HYGIENE + +I purposely refrain from entering into any details as to the character +of the technical work done at the Virchow Institute, because the subject +of pathology, despite its directly practical bearings, is in itself +necessarily somewhat removed from the knowledge of the general reader. +One cannot well understand the details of changes in tissues under +abnormal conditions unless one first understands the normal conditions +of the tissues themselves, and such knowledge is reserved for the +special students of anatomy. For the nonprofessional observer the +interest of the Virchow Institute must lie in its general scope rather +than in the details of the subjects there brought under investigation, +which latter have, indeed, of necessity, a somewhat grewsome character +despite the beneficent results that spring from them. It is quite +otherwise, however, with the work of the allied institution of which I +now come to speak. The Institute of Hygiene deals with topics not very +remote from those studied in the Virchow Institute, part of its work, +indeed, falling clearly within the scope of pathology; but it differs in +being clearly comprehensible to the general public and of immediate +and tangible interest from the most strictly utilitarian stand-point, +hygiene being, in effect, the tangible link between the more abstract +medical sciences and the affairs of every-day life. + +The Institute of Hygiene has also the interest that always attaches to +association with a famous name, for it was here that Professor Koch made +the greater part of those investigations which made his name the best +known, next to that of Pasteur, of any in the field of bacteriology. +In particular, the researches on the cholera germ, and those even more +widely heralded researches that led to the discovery of the bacillus of +tuberculosis, and the development of the remedy tuberculin, of which +so much was at first expected, were made by Professor Koch in the +laboratories of the antiquated building which was then and is still +the seat of the Institute of Hygiene. More recently Professor Koch has +severed his connection with the institution after presiding over it for +many years, having now a semi-private laboratory just across from the +Virchow Institute, in connection with the Charite Hospital; but one +still thinks of the Institute of Hygiene as peculiarly the "Koch +Institute" without injustice, so fully does its work follow the lines +laid out for it by the great leader. + +But however much the stamp of any individual personality may rest upon +the institute, it is officially a department of the university, just as +is the Virchow Institute. Like the latter, also, its local habitation +is an antiquated building, strangely at variance, according to American +ideas, with its reputation, though by no means noteworthy in this regard +in the case of a German institution. It is situated in a part of the +city distant from any other department of the university, and there is +nothing about it exteriorly to distinguish it from other houses of the +solid block in which it stands. Interiorly, it reminds one rather of a +converted dwelling than a laboratory proper. Its rooms are well +enough adapted to their purpose, but they give one the impression of +a makeshift. The smallest American college would be ill-satisfied with +such an equipment for any department of its work. Yet in these dingy +quarters has been accomplished some of the best work in the new science +of bacteriology that our century will have to boast. + +The actual equipment of the bacteriological laboratory here is not, +indeed, quite as meagre as it seems at first, there being numerous +rooms, scattered here and there, which in the aggregate give opportunity +for work to a large number of investigators, though no single room makes +an impressive appearance. There is one room, however, large enough to +give audience to a considerable class, and here lectures were given by +Professor Koch and continue to be given by his successors to the special +students of bacteriology who come from all over the world, as well as to +the university students who take the course as a part of their regular +medical curriculum. In regard to this feature of its work, the Institute +of Hygiene differs in no essential respect from the Pasteur Institute +and other laboratories of bacteriology. The same general routine of work +pertains: the patient cultivation of the minute organisms in various +mediums, their careful staining by special processes, and their +investigation under the microscope mark the work of the bacteriologist +everywhere. Many details of the special methods of culture or treatment +originated here with Professor Koch, but such matters are never kept +secret in science, so one may see them practised quite as generally +and as efficiently in other laboratories as in this one. Indeed, it may +frankly be admitted that, aside from its historical associations with +the pioneer work in bacteriology, which will always make it memorable, +there is nothing about the bacteriological laboratory here to give it +distinction over hundreds of similar ones elsewhere; while in point of +technical equipment, as already noted, it is remarkable rather for what +it lacks than for what it presents. + +The department of bacteriology, however, is only one of several +important features of the institute. One has but to ascend another +flight of stairs to pass out of the sphere of the microbe and enter a +department where attention is directed to quite another field. We have +now come to what may be considered the laboratory of hygiene proper, +since here the investigations have to do directly with the functionings +of the human body in their relations to the every-day environment. +Here again one is struck with the meagre equipment with which important +results may be attained by patient and skilled investigators. In only +one room does one find a really elaborate piece of apparatus. This +exceptional mechanism consists essentially of a cabinet large enough to +give comfortable lodgment to a human subject--a cabinet with walls of +peculiar structure, partly of glass, and connected by various pipes with +sundry mysterious-seeming retorts. This single apparatus, however, is +susceptible of being employed for the investigation of an almost endless +variety of questions pertaining to the functionings of the human body +considered as a working mechanism. + +Thus, for example, a human subject to be experimented upon may remain +for an indefinite period within this cabinet, occupied in various ways, +taking physical exercise, reading, engaged in creative mental labor, +or sleeping. Meantime, air is supplied for respiration in measured +quantities, and of a precisely determined composition, as regards +chemical impurities, moisture, and temperature. The air after passing +through the chamber being again analyzed, the exact constituents added +to it as waste products of the human machine in action under varying +conditions are determined. It will readily be seen that by indefinitely +varying the conditions of such experiments a great variety of data +may be secured as to the exact physiological accompaniments of various +bodily and mental activities. Such data are of manifest importance to +the physiologist and pathologist on the one hand, while at the same +time having a direct bearing on such eminently practical topics as the +construction of shops, auditoriums, and dwellings in reference to light, +heat, and ventilation. It remains only for practical architecture to +take advantage of the unequivocal data thus placed at its disposal--an +opportunity of which practical architecture, in Germany as elsewhere on +the Continent, has hitherto been very slow to avail itself. + + +THE MUSEUM OF HYGIENE + +The practical lessons thus given in the laboratory are supplemented in +an even more tangible manner, because in a way more accessible to +the public, in another department of the institution which occupies a +contiguous building, and is known as the Museum of Hygiene. This, unlike +the other departments of the institute, is open to the general public +on certain days of each week, and it offers a variety of exhibits of +distinctly novel character and of high educational value. The general +character of the exhibits may be inferred from the name, but perhaps the +scope is even wider than might be expected. In a word, it may be said +that scarcely anything having to do with practical hygiene has been +overlooked. Thus one finds here numberless models of dwelling-houses, +showing details of lighting, heating, and ventilation; models not +merely of individual dwellings, but also of school-buildings, hospitals, +asylums, and even prisons. Sometimes the models represent merely +ideal buildings, but more generally they reproduce in miniature actual +habitations. In the case of the public buildings, the model +usually includes not merely the structures themselves but the +surroundings--lawns, drives, trees, out-buildings--so that one can get a +very good idea of the more important hospitals, asylums, and prisons of +Germany by making a tour of the Museum of Hygiene. Regarding the details +of structure, one can actually gain a fuller knowledge in many cases +than he could obtain by actual visits to the original institutions +themselves. + +The same thing is true of various other features of the subjects +represented. Thus there is a very elaborate model here exhibited of the +famous Berlin system of sewage-disposal. As is well known, the essential +features of this system consist of the drainage of sewage into local +reservoirs, from which it is forced by pumps, natural drainage not +sufficing, to distant fields, where it is distributed through tile pipes +laid in a network about a yard beneath the surface of the soil. The +fields themselves, thus rendered fertile by the waste products of the +city, are cultivated, and yield a rich harvest of vegetables and grains +of every variety suitable to the climate. The visitor to this field +sees only rich farms and market-gardens under ordinary process of +cultivation. The system of pipes by which the land is fertilized is +as fully hidden from his view as are, for example, the tributary +sewage-pipes beneath the city pavements. The average visitor to Berlin +knows nothing, of course, about one or the other, and goes away, as he +came, ignorant of the important fact that Berlin has reached a better +solution of the great sewage problem than has been attained by any +other large city. Such, at least, is likely to be the case unless the +sight-seer chance to pay a visit to the Museum of Hygiene, in which +case a few minutes' inspection of the model there will make the matter +entirely clear to him. It is to be regretted that the authorities +of other large cities do not make special visits to Berlin for this +purpose; though it should be added that some of them have done so, and +that the Berlin system of "canalization" has been adopted in various +places in America. But many others might wisely follow their example, +notably the Parisians, whose sewerage system, despite the boasted +exhibition canal-sewer, is, like so many other things Parisian, of the +most primitive character and a reproach to present-day civilization. + +It may be added that there are plenty of things exhibited in this museum +which the Germans themselves might study to advantage, for it must be +understood that the other hygienic conditions pertaining to Berlin are +by no means all on a par with the high modern standard of the sewerage +system. In the matter of ventilation, for example, one may find +admirable models in the museum, showing just how the dwelling and shop +and school-room should make provision for a proper supply of pure air +for their occupants. But if one goes out from the museum and searches in +the actual dwelling or shop or school-room for the counterparts of +these models, one will be sorely puzzled where to find them. The general +impression which a casual inspection will leave in his mind is that the +word ventilation must be as meaningless to the German mind as it is, for +example, to the mind of a Frenchman or an Italian. This probably is not +quite just, since the German has at least reached the stage of having +museum models of ventilated houses, thus proving that the idea does +exist, even though latent, in his mental equipment, whereas the other +continental nationalities seem not to have reached even this incipient +stage of progress. All over Europe the people fear a current of air as +if veritable miasm must lurk in it. They seem quite oblivious to any +systematic necessity for replenishing the oxygen supply among large +assemblies, as any one can testify who has, for example, visited their +theatres or schools. And as to the private dwellings, after making +them as nearly air-tight as practicable, they endeavor to preserve the +_status quo_ as regards air supply seemingly from season to season. They +even seem to have passed beyond a mere negative regard for the subject +of fresh air, inasmuch as they will bravely assure you that to sleep +in a room with an open window will surely subject you to the penalty of +inflamed eyes. + +In a country like France, where the open fireplace is the usual means +employed to modify the temperature (I will not say warm the room), +the dwellings do of necessity get a certain amount of ventilation, +particularly since the windows are not usually of the best construction. +But the German, with his nearly air-tight double windows and his even +more nearly sealed tile stove, spends the winter in an atmosphere +suggestive of the descriptions that arctic travellers give us of the +air in the hut of an Eskimo. It is clear, then, that the models in the +Museum of Hygiene have thus far failed of the proselyting purpose +for which they were presumably intended. How it has chanced that the +inhabitants of the country maintain so high an average of robust health +after this open defiance is a subject which the physiological department +of the Institute of Hygiene might well investigate. + +Even though the implied precepts of the Museum of Hygiene are so largely +disregarded, however, it must be admitted that the existence of the +museum is a hopeful sign. It is a valuable educational institution, +and if its salutary lessons are but slowly accepted by the people, they +cannot be altogether without effect. At least the museum proves that +there are leaders in science here who have got beyond the range of +eighteenth-century thought in matters of practical living, and the +sign is hopeful for the future, though its promise will perhaps not be +fulfilled in our generation. + + + + +VII. SOME UNSOLVED SCIENTIFIC PROBLEMS + + +IN recent chapters we have witnessed a marvellous development in many +branches of pure science. In viewing so wonderfully diversified a field, +it has of course been impossible to dwell upon details, or even to +glance at every minor discovery. At best one could but summarize the +broad sweep of progress somewhat as a battle might be described by a +distant eye-witness, telling of the general direction of action, of +the movements of large masses, the names of leaders of brigades and +divisions, but necessarily ignoring the lesser fluctuations of advance +or recession and the individual gallantry of the rank and file. In +particular, interest has centred upon the storming of the various +special strongholds of ignorant or prejudiced opposition, which at last +have been triumphantly occupied by the band of progress. In each case +where such a stronghold has fallen, the victory has been achieved solely +through the destructive agency of newly discovered or newly marshalled +facts--the only weapons which the warrior of science seeks or cares for. +Facts must be marshalled, of course, about the guidon of a hypothesis, +but that guidon can lead on to victory only when the facts themselves +support it. Once planted victoriously on the conquered ramparts the +hypothesis becomes a theory--a generalization of science--marking a +fresh coign of vantage, which can never be successfully assailed unless +by a new host of antagonistic facts. Such generalizations, with the +events leading directly up to them, have chiefly occupied our attention. + +But a moment's reflection makes it clear that the battle of science, +thus considered, is ever shifting ground and never ended. Thus at +any given period there are many unsettled skirmishes under way; many +hypotheses are yet only struggling towards the stronghold of theory, +perhaps never to attain it; in many directions the hosts of antagonistic +facts seem so evenly matched that the hazard of war appears uncertain; +or, again, so few facts are available that as yet no attack worthy the +name is possible. Such unsettled controversies as these have, for the +most part, been ignored in our survey of the field. But it would not be +fair to conclude our story without adverting to them, at least in brief; +for some of them have to do with the most comprehensive and important +questions with which science deals, and the aggregate number of facts +involved in these unfinished battles is often great, even though as yet +the marshalling has not led to final victory for any faction. In some +cases, doubtless, the right hypothesis is actually in the field, but its +supremacy not yet conclusively proved--perhaps not to be proved for many +years or decades to come. Some of the chief scientific results of the +nineteenth century have been but the gaining of supremacy for hypotheses +that were mere forlorn hopes, looked on with general contempt, if at +all heeded, when the eighteenth century came to a close--witness the +doctrines of the great age of the earth, of the immateriality of heat, +of the undulatory character of light, of chemical atomicity, of +organic evolution. Contrariwise, the opposite ideas to all of these +had seemingly a safe supremacy until the new facts drove them from the +field. Who shall say, then, what forlorn hope of to-day's science may +not be the conquering host of to-morrow? All that one dare attempt is +to cite the pretensions of a few hypotheses that are struggling over the +still contested ground. + + +SOLAR AND TELLURIC PROBLEMS + +Our sun being only a minor atom of the stellar pebble, solar problems +in general are of course stellar problems also. But there are certain +special questions regarding which we are able to interrogate the sun +because of his proximity, and which have, furthermore, a peculiar +interest for the residents of our little globe because of our dependence +upon this particular star. One of the most far-reaching of these is +as to where the sun gets the heat that he gives off in such +liberal quantities. We have already seen that Dr. Mayer, of +conservation-of-energy fame, was the first to ask this question. As +soon as the doctrine of the persistence and convertibility of energy was +grasped, about the middle of the century, it became clear that this +was one of the most puzzling of questions. It did not at all suffice to +answer that the sun is a ball of fire, for computation showed that, at +the present rate of heat-giving, if the sun were a solid mass of coal, +he would be totally consumed in about five thousand years. As no such +decrease in size as this implies had taken place within historic times, +it was clear that some other explanation must be sought. + +Dr. Mayer himself hit upon what seemed a tenable solution at the very +outset. Starting from the observed fact that myriads of tiny meteorites +are hurled into the earth's atmosphere daily, he argued that the sun +must receive these visitants in really enormous quantities--sufficient, +probably, to maintain his temperature at the observed limits. There was +nothing at all unreasonable about this assumption, for the amount of +energy in a swiftly moving body capable of being transformed into heat +if the body be arrested is relatively enormous. Thus it is calculated +that a pound of coal dropped into the sun from the mathematician's +favorite starting-point, infinity, would produce some six thousand times +the heat it could engender if merely burned at the sun's surface. In +other words, if a little over two pounds of material from infinity +were to fall into each square yard of the sun's surface each hour, his +observed heat would be accounted for; whereas almost seven tons per +square yard of stationary fuel would be required each hour to produce +the same effect. + +In view of the pelting which our little earth receives, it seemed not +an excessive requisition upon the meteoric supply to suppose that the +requisite amount of matter may fall into the sun, and for a time this +explanation of his incandescence was pretty generally accepted. But soon +astronomers began to make calculations as to the amount of matter which +this assumption added to our solar system, particularly as it aggregated +near the sun in the converging radii, and then it was clear that no such +mass of matter could be there without interfering demonstrably with the +observed course of the interior planets. So another source of the sun's +energy had to be sought. It was found forthwith by that other great +German, Helmholtz, who pointed out that the falling matter through which +heat may be generated might just as well be within the substance of the +sun as without--in other words, that contraction of the sun's heated +body is quite sufficient to account for a long-sustained heat-supply +which the mere burning of any known substance could not approach. +Moreover the amount of matter thus falling towards the sun's centre +being enormous--namely, the total substance of the sun--a relatively +small amount of contraction would be theoretically sufficient to keep +the sun's furnace at par, so to speak. + +At first sight this explanation seemed a little puzzling to many laymen +and some experts, for it seemed to imply, as Lord Kelvin pointed out, +that the sun contracts because it is getting cooler, and gains heat +because it contracts. But this feat is not really as paradoxical as it +seems, for it is not implied that there is any real gain of heat in the +sun's mass as a whole, but quite the reverse. All that is sought is +an explanation of a maintenance of heat-giving capacity relatively +unchanged for a long, but not an interminable, period. Indeed, +exactly here comes in the novel and startling feature of. Helmholtz's +calculation. According to Mayer's meteoric hypothesis, there were no +data at hand for any estimate whatever as to the sun's permanency, since +no one could surmise what might be the limits of the meteoric supply. +But Helmholtz's estimate implied an incandescent body cooling--keeping +up a somewhat equable temperature through contraction for a time, but +for a limited time only; destined ultimately to become liquid, solid; to +cool below the temperature of incandescence--to die. Not only so, but +it became possible to calculate the limits of time within which this +culmination would probably occur. It was only necessary to calculate the +total amount of heat which could be generated by the total mass of our +solar system in falling together to the sun's centre from "infinity" to +find the total heat-supply to be drawn upon. Assuming, then, that the +present observed rate of heat-giving has been the average maintained +in the past, a simple division gives the number of years for which the +original supply is adequate. The supply will be exhausted, it will be +observed, when the mass comes into stable equilibrium as a solid body, +no longer subject to contraction, about the sun's centre--such a body, +in short, as our earth is at present. + +This calculation was made by Lord Kelvin, Professor Tait, and others, +and the result was one of the most truly dynamitic surprises of the +century. For it transpired that, according to mathematics, the entire +limit of the sun's heat-giving life could not exceed something like +twenty-five millions of years. The publication of that estimate, with +the appearance of authority, brought a veritable storm about the heads +of the physicists. The entire geological and biological worlds were +up in arms in a trice. Two or three generations before, they hurled +brickbats at any one who even hinted that the solar system might be more +than six thousand years old; now they jeered in derision at the attempt +to limit the life-bearing period of our globe to a paltry fifteen or +twenty millions. + +The controversy as to solar time thus raised proved one of the most +curious and interesting scientific disputations of the century. The +scene soon shifted from the sun to the earth; for a little reflection +made it clear that the data regarding the sun alone were not +sufficiently definite. Thus Dr. Croll contended that if the parent +bodies of the sun had chanced to be "flying stars" before collision, +a vastly greater supply of heat would have been engendered than if the +matter merely fell together. Again, it could not be overlooked that +a host of meteors are falling into the sun, and that this source of +energy, though not in itself sufficient to account for all the heat in +question, might be sufficient to vitiate utterly any exact calculations. +Yet again, Professor Lockyer called attention to another source of +variation, in the fact that the chemical combination of elements +hitherto existing separately must produce large quantities of heat, it +being even suggested that this source alone might possibly account for +all the present output. On the whole, then, it became clear that the +contraction theory of the sun's heat must itself await the demonstration +of observed shrinkage of the solar disk, as viewed by future generations +of observers, before taking rank as an incontestable theory, and that +computations as to time based solely on this hypothesis must in the mean +time be viewed askance. + +But the time controversy having taken root, new methods were naturally +found for testing it. The geologists sought to estimate the period of +time that must have been required for the deposit of the sedimentary +rocks now observed to make up the outer crust of the earth. The amount +of sediment carried through the mouth of a great river furnishes a clew +to the rate of denudation of the area drained by that river. Thus the +studies of Messrs. Humphreys and Abbot, made for a different purpose, +show that the average level of the territory drained by the Mississippi +is being reduced by about one foot in six thousand years. The sediment +is, of course, being piled up out in the Gulf at a proportionate rate. +If, then, this be assumed to be an average rate of denudation and +deposit in the past, and if the total thickness of sedimentary deposits +of past ages were known, a simple calculation would show the age of the +earth's crust since the first continents were formed. But unfortunately +these "ifs" stand mountain-high here, all the essential factors being +indeterminate. Nevertheless, the geologists contended that they could +easily make out a case proving that the constructive and destructive +work still in evidence, to say nothing of anterior revolutions, could +not have been accomplished in less than from twenty-five to fifty +millions of years. + +This computation would have carried little weight with the physicists +had it not chanced that another computation of their own was soon made +which had even more startling results. This computation, made by Lord +Kelvin, was based on the rate of loss of heat by the earth. It thus +resembled the previous solar estimate in method. But the result was very +different, for the new estimate seemed to prove that a period of from +one hundred to two hundred millions of years has elapsed since the final +crust of the earth formed. + +With this all controversy ceased, for the most grasping geologist or +biologist would content himself with a fraction of that time. But the +case for the geologist was to receive yet another prop from the studies +of radio-activity, which seem to prove that the atom of matter has in +store a tremendous, supply of potential energy which may be drawn on +in a way to vitiate utterly all the computations to which I have just +referred. Thus a particle of radium is giving out heat incessantly +in sufficient quantity to raise its own weight of water to the +boiling-point in an hour. The demonstrated wide distribution of +radio-active matter--making it at least an open question whether all +matter does not possess this property in some degree--has led to the +suggestion that the total heat of the sun may be due to radio-active +matter in its substance. Obviously, then, all estimates of the sun's age +based on the heat-supply must for the present be held quite in abeyance. +What is more to the point, however, is the fact, which these varying +estimates have made patent, that computations of the age of the earth +based on any data at hand are little better than rough guesses. Long +before the definite estimates were undertaken, geologists had proved +that the earth is very, very old, and it can hardly be said that +the attempted computations have added much of definiteness to that +proposition. They have, indeed, proved that the period of time to be +drawn upon is not infinite; but the nebular hypothesis, to say nothing +of common-sense, carried us as far as that long ago. + +If the computations in question have failed of their direct purpose, +however, they have been by no means lacking in important collateral +results. To mention but one of these, Lord Kelvin was led by this +controversy over the earth's age to make his famous computation in which +he proved that the telluric structure, as a whole, must have at least +the rigidity of steel in order to resist the moon's tidal pull as it +does. Hopkins had, indeed, made a somewhat similar estimate as early as +1839, proving that the earth's crust must be at least eight hundred or +a thousand miles in thickness; but geologists had utterly ignored +this computation, and the idea of a thin crust on a fluid interior had +continued to be the orthodox geological doctrine. Since Lord Kelvin's +estimate was made, his claim that the final crust of the earth could +not have formed until the mass was solid throughout, or at least until +a honeycomb of solid matter had been bridged up from centre to +circumference, has gained pretty general acceptance. It still remains +an open question, however, as to what proportion the lacunas of molten +matter bear at the present day to the solidified portions, and therefore +to what extent the earth will be subject to further shrinkage and +attendant surface contortions. That some such lacunae do exist is +demonstrated daily by the phenomena of volcanoes. So, after all, the +crust theory has been supplanted by a compromise theory rather than +completely overthrown, and our knowledge of the condition of the +telluric depths is still far from definite. If so much uncertainty +attends these fundamental questions as to the earth's past and present, +it is not strange that open problems as to her future are still +more numerous. We have seen how, according to Professor Darwin's +computations, the moon threatens to come back to earth with destructive +force some day. Yet Professor Darwin himself urges that there are +elements of fallibility in the data involved that rob the computation of +all certainty. Much the same thing is true of perhaps all the estimates +that have been made as to the earth's ultimate fate. Thus it has been +suggested that, even should the sun's heat not forsake us, our day will +become month-long, and then year-long; that all the water of the globe +must ultimately filter into its depths, and all the air fly off into +space, leaving our earth as dry and as devoid of atmosphere as the moon; +and, finally, that ether-friction, if it exist, or, in default of that, +meteoric friction, must ultimately bring the earth back to the sun. But +in all these prognostications there are possible compensating factors +that vitiate the estimates and leave the exact results in doubt. The +last word of the cosmic science of our generation is a prophecy of +evil--if annihilation be an evil. But it is left for the science of +another generation to point out more clearly the exact terms in which +the prophecy is most likely to be fulfilled. + + +PHYSICAL PROBLEMS + +In regard to all these cosmic and telluric problems, it will be seen, +there is always the same appeal to one central rule of action--the law +of gravitation. When we turn from macrocosm to microcosm it would +appear as if new forces of interaction were introduced in the powers of +cohesion and of chemical action of molecules and atoms. But Lord Kelvin +has argued that it is possible to form such a conception of the forms +and space relations of the ultimate particles of matter that their +mutual attractions may be explained by invoking that same law of +gravitation which holds the stars and planets in their course. What, +then, is this all-compassing power of gravitation which occupies so +central a position in the scheme of mechanical things? + +The simple answer is that no man knows. The wisest physicist of +to-day will assure you that he knows absolutely nothing of the why of +gravitation--that he can no more explain why a stone tossed into the +air falls back to earth than can the boy who tosses the stone. But while +this statement puts in a nutshell the scientific status of explanations +of gravitation, yet it is not in human nature that speculative +scientists should refrain from the effort to explain it. Such efforts +have been made; yet, on the whole, they are surprisingly few in number; +indeed, there are but two that need claim our attention here, and one +of these has hardly more than historical interest. One of these is the +so-called ultramundane-corpuscle hypothesis of Le Sage; the other is +based on the vortex theory of matter. + +The theory of Le Sage assumes that the entire universe is filled with +infinitely minute particles flying in right lines in every direction +with inconceivable rapidity. Every mass of tangible matter in the +universe is incessantly bombarded by these particles, but any two +non-contiguous masses (whether separated by an infinitesimal space or by +the limits of the universe) are mutually shielded by one another from a +certain number of the particles, and thus impelled towards one another +by the excess of bombardment on their opposite sides. What applies to +two masses applies also, of course, to any number of masses--in short, +to all the matter in the universe. To make the hypothesis workable, so +to say, it is necessary to assume that the "ultramundane" particles are +possessed of absolute elasticity, so that they rebound from one another +on collision without loss of speed. It is also necessary to assume that +all tangible matter has to an almost unthinkable degree a sievelike +texture, so that the vast proportion of the coercive particles pass +entirely through the body of any mass they encounter--a star or world, +for example--without really touching any part of its actual substance. +This assumption is necessary because gravitation takes no account of +mere corporeal bulk, but only of mass or ultimate solidarity. Thus a +very bulky object may be so closely meshed that it retards +relatively few of the corpuscles, and hence gravitates with relative +feebleness--or, to adopt a more familiar mode of expression, is light in +weight. + +This is certainly heaping hypotheses together in a reckless way, and +it is perhaps not surprising that Le Sage's conception did not at first +arouse any very great amount of interest. It was put forward about +a century ago, but for two or three generations remained practically +unnoticed. The philosophers of the first half of our century seem +to have despaired of explaining gravitation, though Faraday long +experimented in the hope of establishing a relation between gravitation +and electricity or magnetism. But not long after the middle of +the century, when a new science of dynamics was claiming paramount +importance, and physicists were striving to express all tangible +phenomena intenus of matter in motion, the theory of Le Sage was +revived and given a large measure of attention. It seemed to have at +least the merit of explaining the facts without conflicting with any +known mechanical law, which was more than could be said of any other +guess at the question that had ever been made. + +More recently, however, another explanation has been found which also +meets this condition. It is a conception based, like most other physical +speculations of the last generation, upon the hypothesis of the vortex +atom, and was suggested, no doubt, by those speculations which consider +electricity and magnetism to be conditions of strain or twist in +the substance of the universal ether. In a word, it supposes that +gravitation also is a form of strain in this ether--a strain that may be +likened to a suction which the vortex atom is supposed to exert on the +ether in which it lies. According to this view, gravitation is not +a push from without, but a pull from within; not due to exterior +influences, but an inherent and indissoluble property of matter itself. +The conception has the further merit of correlating gravitation with +electricity, magnetism, and light, as a condition of that strange +ethereal ocean of which modern physics takes so much account. But +here, again, clearly, we are but heaping hypothesis upon hypothesis, +as before. Still, an hypothesis that violates no known law and has the +warrant of philosophical probability is always worthy of a hearing. But +we must not forget that it is hypothesis only, not conclusive theory. + +The same caution applies, manifestly, to all the other speculations +which have the vortex atom, so to say, for their foundation-stone. Thus +Professors Stewart and Tait's inferences as to the destructibility +of matter, based on the supposition that the ether is not quite +frictionless; Professor Dolbear's suggestions as to the creation of +matter through the development of new ether ripples, and the same +thinker's speculations as to an upper limit of temperature, based on the +mechanical conception of a limit to the possible vibrations of a vortex +ring, not to mention other more or less fascinating speculations based +on the vortex hypothesis, must be regarded, whatever their intrinsic +interest, as insecurely grounded, until such time as new experimental +methods shall give them another footing. Lord Kelvin himself holds all +such speculations utterly in abeyance. "The vortex theory," he says, +"is only a dream. Itself unproven, it can prove nothing, and any +speculations founded upon it are mere dreams about a dream."*1* + +That certainly must be considered an unduly modest pronouncement +regarding the only workable hypothesis of the constitution of matter +that has ever been imagined; yet the fact certainly holds that the +vortex theory, the great contribution of the nineteenth century towards +the solution of a world-old problem, has not been carried beyond +the stage of hypothesis, and must be passed on, with its burden of +interesting corollaries, to another generation for the experimental +evidence that will lead to its acceptance or its refutation. Our century +has given experimental proof of the existence of the atom, but has not +been able to fathom in the same way the exact form or nature of this +ultimate particle of matter. + +Equally in the dark are we as to the explanation of that strange +affinity for its neighbors which every atom manifests in some degree. +If we assume that the power which holds one atom to another is the same +which in the case of larger bodies we term gravitation, that answer +carries us but a little way, since, as we have seen, gravitation itself +is the greatest of mysteries. But again, how chances it that different +atoms attract one another in such varying degrees, so that, for example, +fluorine unites with everything it touches, argon with nothing? And how +is it that different kinds of atoms can hold to themselves such varying +numbers of fellow-atoms--oxygen one, hydrogen two, and so on? These +are questions for the future. The wisest chemist does not know why the +simplest chemical experiment results as it does. Take, for example, a +water-like solution of nitrate of silver, and let fall into it a few +drops of another water-like solution of hydrochloric acid; a white +insoluble precipitate of chloride of silver is formed. Any tyro in +chemistry could have predicted the result with absolute certainty. But +the prediction would have been based purely upon previous empirical +knowledge--solely upon the fact that the thing had been done before +over and over, always with the same result. Why the silver forsook the +nitrogen atom and grappled the atom of oxygen no one knows. Nor can any +one as yet explain just why it is that the new compound is an insoluble, +colored, opaque substance, whereas the antecedent ones were soluble, +colorless, and transparent. More than that, no one can explain with +certainty just what is meant by the familiar word soluble itself. That +is to say, no one knows just what happens when one drops a lump of salt +or sugar into a bowl of water. We may believe with Professor Ostwald +and his followers that the molecules of sugar merely glide everywhere +between the molecules of water, without chemical action; or, on the +other hand, dismissing this mechanical explanation, we may say with +Mendeleef that the process of solution is the most active of chemical +phenomena, involving that incessant interplay of atoms known as +dissociation. But these two explanations are mutually exclusive, and +nobody can say positively which one, if either, is right. Nor is either +theory at best more than a half explanation, for the why of the strange +mechanical or chemical activities postulated is quite ignored. How is +it, for example, that the molecules of water are able to loosen the +intermolecular bonds of the sugar particles, enabling them to scamper +apart? + +But, for that matter, what is the nature of these intermolecular bonds +in any case? And why, at the same temperature, are some substances held +together with such enormous rigidity, others so loosely? Why does not +a lump of iron dissolve as readily as the lump of sugar in our bowl +of water? Guesses may be made to-day at these riddles, to be sure, but +anything like tenable solutions will only be possible when we know much +more than at present of the nature of intermolecular forces and of the +mechanism of molecular structures. As to this last, studies are +under way that are full of promise. For the past ten or fifteen years +Professor Van 't Hoof of Amsterdam (now of Berlin), with a company of +followers, has made the space relations of atoms a special study, with +the result that so-called stereo-chemistry has attained a firm position. +A truly amazing insight has been gained into the space relations of the +molecules of carbon compounds in particular, and other compounds are +under investigation. But these results, wonderful though they seem +when the intricacy of the subject is considered, are, after all, only +tentative. It is demonstrated that some molecules have their atoms +arranged in perfectly definite and unalterable schemes, but just how +these systems are to be mechanically pictured--whether as miniature +planetary systems or what not--remains for the investigators of the +future to determine. + +It appears, then, that whichever way one turns in the realm of the atom +and molecule, one finds it a land of mysteries. In no field of science +have more startling discoveries been made in the past century than here; +yet nowhere else do there seem to lie wider realms yet unfathomed. + + +LIFE PROBLEMS + +In the life history of at least one of the myriad star systems there +has come a time when, on the surface of one of the minor members of the +group, atoms of matter have been aggregated into such associations as +to constitute what is called living matter. A question that at once +suggests itself to any one who conceives even vaguely the relative +uniformity of conditions in the different star groups is as to whether +other worlds than ours have also their complement of living forms. +The question has interested speculative science more perhaps in our +generation than ever before, but it can hardly be said that much +progress has been made towards a definite answer. At first blush the +demonstration that all the worlds known to us are composed of the same +matter, subject to the same general laws, and probably passing through +kindred stages of evolution and decay, would seem to carry with it the +reasonable presumption that to all primary planets, such as ours, a +similar life-bearing stage must come. But a moment's reflection shows +that scientific probabilities do not carry one safely so far as +this. Living matter, as we know it, notwithstanding its capacity for +variation, is conditioned within very narrow limits as to physical +surroundings. Now it is easily to be conceived that these peculiar +conditions have never been duplicated on any other of all the myriad +worlds. If not, then those more complex aggregations of atoms which we +must suppose to have been built up in some degree on all cooling globes +must be of a character so different from what we term living matter that +we should not recognize them as such. Some of them may be infinitely +more complex, more diversified in their capacities, more widely +responsive to the influences about them, than any living thing on earth, +and yet not respond at all to the conditions which we apply as tests of +the existence of life. + +This is but another way of saying that the peculiar limitations of +specialized aggregations of matter which characterize what we term +living matter may be mere incidental details of the evolution of our +particular star group, our particular planet even--having some such +relative magnitude in the cosmic order, as, for example, the exact +detail of outline of some particular leaf of a tree bears to the +entire subject of vegetable life. But, on the other hand, it is also +conceivable that the conditions on all planets comparable in position to +ours, though never absolutely identical, yet pass at some stage +through so similar an epoch that on each and every one of them there is +developed something measurably comparable, in human terms, to what +we here know as living matter; differing widely, perhaps, from any +particular form of living being here, yet still conforming broadly to +a definition of living things. In that case the life-bearing stage of +a planet must be considered as having far more general significance; +perhaps even as constituting the time of fruitage of the cosmic +organism, though nothing but human egotism gives warrant to this +particular presumption. + +Between these two opposing views every one is free to choose according +to his preconceptions, for as yet science is unable to give a deciding +vote. Equally open to discussion is that other question, as to whether +the evolution of universal atoms into a "vital" association mass from +which all the diversified forms evolved, or whether such shifting from +the so-called non-vital to the vital was many times repeated--perhaps +still goes on incessantly. It is quite true that the testimony of our +century, so far as it goes, is all against the idea of "spontaneous +generation" under existing conditions. It has been clearly enough +demonstrated that the bacteria and other low forms of familiar life +which formerly were supposed to originate "spontaneously" had a quite +different origin. But the solution of this special case leaves the +general problem still far from solved. Who knows what are the conditions +necessary to the evolution of the ever-present atoms into "vital" +associations? Perhaps extreme pressure may be one of these conditions; +and, for aught any man knows to the contrary, the "spontaneous +generation" of living protoplasms may be taking place incessantly at the +bottom of every ocean of the globe. + +This of course is a mere bald statement of possibilities. It may be met +by another statement of possibilities, to the effect that perhaps the +conditions necessary to the evolution of living matter here may have +been fulfilled but once, since which time the entire current of life on +our globe has been a diversified stream from that one source. Observe, +please, that this assumption does not fall within that category which +I mention above as contraband of science in speaking of the origin of +worlds. The existence of life on our globe is only an incident limited +to a relatively insignificant period of time, and whether the exact +conditions necessary to its evolution pertained but one second or a +hundred million years does not in the least matter in a philosophical +analysis. It is merely a question of fact, just as the particular +temperature of the earth's surface at any given epoch is a question of +fact, the one condition, like the other, being temporary and incidental. +But, as I have said, the question of fact as to the exact time of origin +of life on our globe is a question that science as yet cannot answer. + +But, in any event, what is vastly more important than this question +as to the duration of time in which living matter was evolved is a +comprehension of the philosophical status of this evolution from the +"non-vital" to the "vital." If one assumes that this evolution was +brought about by an interruption of the play of forces hitherto working +in the universe--that the correlation of forces involved was unique, +acting then and then only--by that assumption he removes the question +of the origin of life utterly from the domain of science--exactly as the +assumption of an initial push would remove the question of the origin +of worlds from the domain of science. But the science of to-day most +emphatically demurs to any such assumption. Every scientist with a wide +grasp of facts, who can think clearly and without prejudice over the +field of what is known of cosmic evolution, must be driven to believe +that the alleged wide gap between vital and non-vital matter is largely +a figment of prejudiced human understanding. In the broader view +there seem no gaps in the scheme of cosmic evolution--no break in the +incessant reciprocity of atomic actions, whether those atoms be floating +as a "fire mist" out in one part of space, or aggregated into the +brain of a man in another part. And it seems well within the range of +scientific expectation that the laboratory worker of the future will +learn how so to duplicate telluric conditions that the universal forces +will build living matter out of the inorganic in the laboratory, as they +have done, and perhaps still are doing, in the terrestrial oceans. + +To the timid reasoner that assumption of possibilities may seem +startling. But assuredly it is no more so than seemed, a century ago, +the assumption that man has evolved, through the agency of "natural +laws" only, from the lowest organism. Yet the timidity of that elder +day has been obliged by the progress of the past century to adapt its +conceptions to that assured sequence of events. And some day, in all +probability, the timidity of to-day will be obliged to take that final +logical step which to-day's knowledge foreshadows as a future if not a +present necessity. + + +THE MECHANISM OF THE CELL + +Whatever future science may be able to accomplish in this direction, +however, it must be admitted that present science finds its hands quite +full, without going farther afield than to observe the succession of +generations among existing forms of life. Since the establishment of +the doctrine of organic evolution, questions of heredity, always +sufficiently interesting, have been at the very focus of attention of +the biological world. These questions, under modern treatment, have +resolved themselves, since the mechanism of such transmission has been +proximately understood, into problems of cellular activity. And much +as has been learned about the cell of late, that interesting microcosm +still offers a multitude of intricacies for solution. + +Thus, at the very threshold, some of the most elementary principles of +mechanical construction of the cell are still matters of controversy. On +the one hand, it is held by Professor O. Butschli and his followers that +the substance of the typical cell is essentially alveolar, or foamlike, +comparable to an emulsion, and that the observed reticular structure of +the cell is due to the intersections of the walls of the minute ultimate +globules. But another equally authoritative school of workers holds to +the view, first expressed by Frommann and Arnold, that the reticulum is +really a system of threads, which constitute the most important basis of +the cell structure. It is even held that these fibres penetrate the cell +walls and connect adjoining cells, so that the entire body is a +reticulum. For the moment there is no final decision between these +opposing views. Professor Wilson of Columbia has suggested that both may +contain a measure of truth. + +Again, it is a question whether the finer granules seen within the cell +are or are not typical structures, "capable of assimilation, growth, +and division, and hence to be regarded as elementary units of structure +standing between the cell and the ultimate molecules of living matter." +The more philosophical thinkers, like Spencer, Darwin, Haeckel, +Michael Foster, August Weismann, and many others, believe that such +"intermediate units must exist, whether or not the microscope reveals +them to view." Weismann, who has most fully elaborated a hypothetical +scheme of the relations of the intracellular units, identifies the +larger of these units not with the ordinary granules of the cell, but +with a remarkable structure called chromatin, which becomes aggregated +within the cell nucleus at the time of cellular division--a structure +which divides into definite parts and goes through some most suggestive +manoeuvres in the process of cell multiplication. All these are puzzling +structures; and there is another minute body within the cell, called the +centro-some, that is quite as much so. This structure, discovered by +Van Beneden, has been regarded as essential to cell division, yet some +recent botanical studies seem to show that sometimes it is altogether +wanting in a dividing cell. + +In a word, the architecture of the cell has been shown by modern +researches to be wonderfully complicated, but the accumulating +researches are just at a point where much is obscure about many of +the observed phenomena. The immediate future seems full of promise +of advances upon present understanding of cell processes. But for the +moment it remains for us, as for preceding generations, about the most +incomprehensible, scientifically speaking, of observed phenomena, that a +single microscopic egg cell should contain within its substance all the +potentialities of a highly differentiated adult being. The fact that +it does contain such potentialities is the most familiar of every-day +biological observations, but not even a proximal explanation of the fact +is as yet attainable. + + +THE ANCESTRY OF THE MAMMALS + +Turning from the cell as an individual to the mature organism which +the cell composes when aggregated with its fellows, one finds the +usual complement of open questions, of greater or less significance, +focalizing the attention of working biologists. Thus the evolutionist, +secure as is his general position, is yet in doubt when it comes to +tracing the exact lineage of various forms. He does not know, for +example, exactly which order of invertebrates contains the type from +which vertebrates sprang, though several hotly contested opinions, +each exclusive of the rest, are in the field. Again, there is like +uncertainty and difference of opinion as to just which order of lower +vertebrates formed the direct ancestry of the mammals. Among the mammals +themselves there are several orders, such as the whales, the elephants, +and even man himself, whose exact lines of more immediate ancestry are +not as fully revealed by present paleontology as is to be desired. + + +THE NEW SCIENCE OF ANTHROPOLOGY + +All these, however, are details that hardly take rank with the general +problems that we are noticing. There are other questions, however, +concerning the history and present evolution of man himself that are +of wider scope, or at least seemingly greater importance from a human +stand-point, which within recent decades have come for the first time +within the scope of truly inductive science. These are the problems of +anthropology--a science of such wide scope, such far-reaching collateral +implications, that as yet its specific field and functions are not as +clearly defined or as generally recognized as they are probably destined +to be in the near future. The province of this new science is +to correlate the discoveries of a wide range of collateral +sciences--paleontology, biology, medicine, and so on--from the point +of view of human history and human welfare. To this end all observable +races of men are studied as to their physical characteristics, their +mental and moral traits, their manners, customs, languages, and +religions. A mass of data is already at hand, and in process of sorting +and correlating. Out of this effort will probably come all manner of +useful generalizations, perhaps in time bringing sociology, or the study +of human social relations, to the rank of a veritable science. But great +as is the promise of anthropology, it can hardly be denied that the +broader questions with which it has to deal--questions of race, of +government, of social evolution--are still this side the fixed plane +of assured generalization. No small part of its interest and importance +depends upon the fact that the great problems that engage it are as yet +unsolved problems. In a word, anthropology is perhaps the most important +science in the entire hierarchy to-day, precisely because it is an +immature science. Its position to-day is perhaps not unlike that of +paleontology at the close of the eighteenth century. May its promise +find as full fruition! + + + + +IX. RETROSPECT AND PROSPECT + + +THE SCIENTIFIC ATTITUDE OF MIND + +ANY one who has not had a rigid training in science may advantageously +reflect at some length upon the meaning of true scientific induction. +Various illustrations in our text are meant to convey the idea that +logical thinking consists simply in drawing correct conclusions as to +the probable sequence of events in nature. It will soon be evident to +any one who carefully considers the subject that we know very little +indeed about cause and effect in a rigid acceptance of these words. We +observe that certain phenomena always follow certain other phenomena, +and these observations fix the idea in our mind that such phenomena bear +to one another the relation of effect and cause. The conclusion is a +perfectly valid one so long as we remember that in the last analysis the +words "cause" and "effect" have scarcely greater force than the terms +"invariable antecedent" and "invariable consequent"--that is to say, +they express an observed sequence which our experience has never +contradicted. + +Now the whole structure of science would be hopelessly undermined +had not scientific men come to have the fullest confidence in the +invariability of certain of these sequences of events. Let us, for +example, take the familiar and fundamental observation that any +unsupported object, having what we term weight, invariably falls +directly towards the centre of the earth. We express this fact in +terms of a so-called law of gravitation, and every one, consciously or +unconsciously, gives full deference to this law. So firmly convinced +are we that the gravitation pull is a cause that works with absolute, +unvarying uniformity that we should regard it as a miracle were any +heavy body to disregard the law of gravitation and rise into the air +when not impelled by some other force of which we have knowledge. Thanks +to Newton, we know that this force of gravitation is not at all confined +to the earth, but affects the whole universe, so that every two bits +of matter, regardless of location, pull at each other with a force +proportionate to their mass and inversely as the square of their +distance. + +Were this so-called law of gravitation to cease to operate, the entire +plan of our universe would be sadly disarranged. The earth, for example, +and the other planets would leave their elliptical orbits and hurtle +away on a tangential course. We should soon be beyond the reach of the +sun's beneficent influence; an arctic chill would pervade polar and +tropical regions alike, and the term of man's existence would +come suddenly to a close. Here, then, is a force at once the most +comprehensible and most important from a human stand-point that can be +conceived; yet it cannot be too often repeated, we know nothing whatever +as to the nature of this force. We do not know that there may not be +other starlike clusters beyond our universe where this force does not +prevail. We do not know that there may not come a period when this force +will cease to operate in our universe, and when, for example, it will be +superseded by the universal domination of a force of mutual repulsion. +For aught we know to the contrary, our universe may be a pulsing +organism, or portion of an organism, all the particles of which are at +one moment pulled together and the next moment hurled apart--the moments +of this computation being, of course, myriads of years as we human +pygmies compute time. + +To us it would be a miracle if a heavy body, unsupported, should fly off +into space instead of dropping towards the centre of the earth; yet the +time may come when all such heavy objects will thus fly off into space, +and when the observer, could there be such, must marvel at the miracle +of seeing a heavy object fall towards the earth. Such thoughts as these +should command the attention of every student of science who would +really understand the meaning of what are termed natural laws. But, on +the other hand, such suggestions must be held carefully in check by the +observation that scientific imagining as to what may come to pass at +some remote future time must in no wise influence our practical faith +in the universality of certain natural laws in the present epoch. We may +imagine a time when terrestrial gravitation no longer exerts its power, +but we dare not challenge that power in the present. There could be no +science did we not accept certain constantly observed phenomena as the +effect of certain causes. The whole body of science is made up solely of +such observations and inferences. Natural science is so called because +it has to do with observed phenomena of nature. + + +NATURAL VERSUS SUPERNATURAL + +A further word must be said as to this word "natural," and its +complementary word "supernatural." I have said in an early chapter that +prehistoric man came, through a use of false inductions, to the belief +in supernatural powers. Let us examine this statement in some detail, +for it will throw much light on our later studies. The thing to get +clearly in mind is the idea that when we say "natural" phenomena we +mean merely phenomena that have been observed to occur. From a truly +scientific stand-point there is no preconception as to what manner +of phenomenon may, or may not, occur. All manner of things do occur +constantly that would seem improbable were they not matters of +familiar knowledge. The simplest facts in regard to gravitation involve +difficulties that were stumbling-blocks to many generations of thinkers, +and which continue stumbling-blocks to the minds of each generation of +present-day children. + +Thus most of us can recall a time when we first learned with +astonishment that the earth is "round like a ball"; that there are +people walking about on the other side of the world with their feet +towards ours, and that the world itself is rushing through space +and spinning rapidly about as it goes. Then we learn, further, that +numberless familiar phenomena would be quite different could we be +transported to other globes. That, for example, a man who can spring two +or three feet into the air here would be able, with the same muscular +exertion, to vault almost to the house-tops if he lived on a small +planet like the moon; but, on the other hand, would be held prone by his +own weight if transported to a great planet like Jupiter. + +When, further, we reflect that with all our capacity to measure +and estimate this strange force of gravitation we, after all, know +absolutely nothing as to its real nature; that we cannot even imagine +how one portion of matter can act on another across an infinite abysm +(or, for that matter, across the smallest space), we see at once that +our most elementary scientific studies bring us into the presence of +inscrutable mysteries. In whatever direction we turn this view is +but emphasized. Electricity, magnetism, the hypothetical ether, the +inscrutable forces manifested everywhere in the biological field--all +these are, as regard their ultimate nature, altogether mysterious. + +In a word, the student of nature is dealing everywhere with the +wonderful, the incomprehensible. Yet all the manifestations that he +observes are found to repeat themselves in certain unvarying sequences. +Certain applications of energy will produce certain movements of matter. +We may not know the nature of the so-called cause, but we learn to +measure the result, and in other allied cases we learn to reason back +or infer the cause from observation of results. The latter indeed is +the essence of scientific inquiry. When certain series of phenomena have +been classified together as obviously occurring under the domination +of the same or similar causes, we speak of having determined a law of +nature. For example, the fact that any body in motion tends to go on at +the same rate of speed in a direct line forever, expresses such a law. +The fact that the gravitation pull is directly as the mass and inversely +as the square of the distance of the bodies it involves, expresses +another such law. The fact that the planetary bodies of the solar system +revolve in elliptical orbits under the joint influence of the two laws +just named, expresses yet another law. In a word, then, these so-called +"laws" are nothing more than convenient formulae to express the +classification of observed facts. + + +INDUCTIVE VERSUS DEDUCTIVE REASONING + +The ancient thinkers indulged constantly in what we now speak of +as deductive reasoning. They gave heed to what we term metaphysical +preconceptions as to laws governing natural phenomena. The Greeks, for +example, conceived that the circle is the perfect body, and that the +universe is perfect; therefore, sun and moon must be perfect spheres +or disks, and all the orbits of the heavenly bodies must be exactly +circular. We have seen that this metaphysical conception, dominating the +world for many centuries, exerted a constantly hampering influence upon +the progress of science. There were numerous other instances of the same +retarding influence of deductive reasoning. Modern science tries to cast +aside all such preconceptions. It does not always quite succeed, but +it makes a strenuous effort to draw conclusions logically from observed +phenomena instead of trying to force observations into harmony with +a preconeived idea. Herein lies the essential difference between the +primitive method and the perfected modern method. Neither the one nor +the other is intended to transcend the bounds of the natural. That is +to say, both are concerned with the sequence of actual events, with the +observation of actual phenomena; but the modern observer has the almost +infinite advantage of being able to draw upon an immense store of +careful and accurate observations. A knowledge of the mistakes of +his predecessors has taught him the value of caution in interpreting +phenomena that seem to fall outside the range of such laws of nature +as experience has seemed to demonstrate. Again and again the old +metaphysical laws have been forced aside by observation; as, for +example, when Kepler showed that the planetary orbits are not circular, +and Galileo's telescope proved that the spot-bearing sun cannot be a +perfect body in the old Aristotelian sense. + +New means of observation have from time to time opened up new fields, +yet with all the extensions of our knowledge we come, paradoxically +enough, to realize but the more fully the limitations of that knowledge. +We seem scarcely nearer to-day to a true understanding of the real +nature of the "forces" whose operation we see manifested about us than +were our most primitive ancestors. But in one great essential we have +surely progressed. We have learned that the one true school is the +school of experience; that metaphysical causes are of absolutely no +consequence unless they can gain support through tangible observations. +Even so late as the beginning of the nineteenth century, the great +thinker, Hegel, retaining essentially the Greek cast of thought, could +make the metaphysical declaration that, since seven planets were known, +and since seven is the perfect number, it would be futile to search for +other planets. But even as he made this declaration another planet was +found. It would be safe to say that no thinker of the present day would +challenge defeat in quite the Aristotelian or Hegelian manner; but, +on the other hand, it is equally little open to doubt that, in matters +slightly less susceptible of tangible demonstration, metaphysical +conceptions still hold sway; and as regards the average minds of our +time, it is perhaps not an unfair estimate to say they surely have not +advanced a jot beyond the Aristotelian stand-point. Untrained through +actual experience in any field of inductive science, they remain easy +victims of metaphysical reasoning. Indeed, since the conditions of +civilization throw a protecting influence about us, and make the +civilized man less amenable to results of illogical action than was the +barbarian, it may almost be questioned whether the average person of +to-day is the equal, as a scientific reasoner, of the average man of the +Stone Age. + +A few of the more tangible superstitions of primitive man have been +banished from even the popular mind by the clear demonstration of +science, but a host remains. I venture to question whether, if the test +could be made in the case of ten thousand average persons throughout +Christendom, it would not be found that a majority of these persons +entertain more utterly mistaken metaphysical ideas regarding natural +phenomena than they do truly scientific conceptions. We pride ourselves +on the enlightenment of our age, but our pride is largely based on an +illusion. Mankind at large is still in the dark age. The historian +of the remote future will see no radical distinction between the +superstitions of the thirteenth century and the superstitions of the +nineteenth century. But he will probably admit that a greater change +took place in the world of thought between the year 1859 and the close +of the nineteenth century than had occurred in the lapse of two thousand +years before If this estimate be correct, it is indeed a privilege to +be living in this generation, for we are on the eve of great things, +and beyond question the revolution that is going on about us denotes the +triumph of science and its inductive method. Just in proportion as we +get away from the old metaphysical preconceptions, substituting for them +the new inductive method, just in that proportion do we progress. The +essence of the new method is to have no preconceptions as to the +bounds of nature; to regard no phenomenon, no sequence of phenomena, as +impossible; but, on the other hand, to accept no alleged law, no theory, +no hypothesis, that has not the warrant of observed phenomena in its +favor. + +The great error of the untrained mind of the primitive man was that he +did not know the value of scientific evidence. He made wide leaps from +observed phenomena to imagined causes, quite overlooking the proximal +causes that were near to hand. The untrained observer of to-day makes +the same mistake; hence the continued prevalence of those superstitious +misconceptions which primitive man foisted upon our race. But each new +generation of to-day is coming upon the field better trained in at least +the rudiments of scientific method than the preceding generation, and +this is perhaps the most hopeful feature of present-day education. Some +day every one will understand that there is no valid distinction between +the natural and the supernatural; in fact, that no such thing as a +supernatural phenomenon, in the present-day acceptance of the word, can +conceivably exist. + +All conceivable manifestations of nature are natural, nor can we +doubt that all are reducible to law--that is to say, that they can be +classified and reduced to systems. But the scientific imagination, as +already pointed out, must admit that any and every scientific law of +our present epoch may be negatived in some future epoch. It is always +possible, also, that a seeming law of to-day may be proved false +to-morrow, which is another way of saying that man's classification +improves from generation to generation. For a "natural law," let it +be repeated, is not nature's method, but man's interpretation of that +method. + + +LOGICAL INDUCTION VERSUS HASTY GENERALIZATION + +A great difficulty is found in the fact that men are forever making +generalizations--that is, formulating laws too hastily. A few phenomena +are observed and at once the hypothesis-constructing mind makes a guess +as to the proximal causes of these phenomena. The guess, once formulated +and accepted, has a certain influence in prejudicing the minds of future +observers; indeed, where the phenomena involve obscure principles the +true explanation of which is long deferred, a false generalization +may impress itself upon mankind with such force as to remain a +stumbling-block for an indefinite period. Thus the Ptolemaic conception +of the universe dominated the thought of Europe for a thousand years, +and could not be substituted by the true theory without a fierce +struggle; and, to cite an even more striking illustration, the early +generalizations of primitive man which explain numberless phenomena of +nature as due to an influence of unseen anthropomorphic beings remain +to this day one of the most powerful influences that affect our race--an +influence from which we shall never shake ourselves altogether free +until the average man--and particularly the average woman--learns to be +a good observer and a logical reasoner. + +Something towards this end is being accomplished by the introduction of +experimental research and scientific study in general in our schools +and colleges. It is hoped that something towards the same end may be +accomplished through study of the history of the development of science. +Scarcely anything is more illuminative than to observe critically the +mistakes of our predecessors, noting how natural the mistakes were and +how tenaciously they were held to, how strenuously defended. Most of +all it would be of value to note that the false inductions which +have everywhere hampered the progress of science have been, from the +stand-point of the generation in which they originated, for the most +part logical inductions. We have seen that the Ptolemaic scheme of the +universe, false though it was in its very essentials, yet explained +in what may be termed a thoroughly scientific fashion the observed +phenomena. It is one way of expressing a fact to say that the sun moves +across the heavens from the eastern to the western horizon; and for most +practical purposes this assumption answers perfectly. It is only when +we endeavor to extend the range of theoretical astronomy, and to gain a +correct conception of the mechanism of the universe as a whole, that +the essentially faulty character of the geocentric conception becomes +apparent. + +And so it is in many another field; the false generalizations and hasty +inductions serve a temporary purpose. Our only quarrel with them is that +they tend through a sort of inertia to go forever unchanged. It requires +a powerful thrust to divert the aggregate mind of our race from a given +course, nor is the effect of a new impulse immediately appreciable; that +is why the masses of the people always lag a generation or two +behind the advanced thinkers. A few receptive minds, cognizant of new +observations that refute an old generalization, accept new laws, and, +from the vantage-ground thus gained, reach out after yet other truths. +But, for the most part, the new laws thus accepted by the leaders remain +unknown to the people at large for at least one or two generations. It +required about a century for the heliocentric doctrine of Copernicus to +begin to make its way. + +In this age of steam and electricity, progress is more rapid, and the +greatest scientific conception of the nineteenth century, the Darwinian +theory, may be said to have made something that approaches an absolute +conquest within less than half a century. This seems a marvellously +sudden conquest, but it must be understood that it is only the crude and +more tangible bearings of the theory that have thus made their way. The +remoter consequences of the theory are not even suspected by the great +majority of those who call themselves Darwinians to-day. It will require +at least another century for these ideas to produce their full effect. +Then, in all probability, it will appear that the nineteenth century +was the most revolutionary epoch by far that the history of thought has +known. And it owes this proud position to the fact that it was the epoch +in all history most fully subject to the dominant influence of inductive +science. Thanks to this influence, we of the new generation are able to +start out on a course widely divergent from the path of our +ancestors. Our leaders of thought have struggled free from the bogs +of superstition, and are pressing forward calmly yet with exultation +towards the heights. + + + + +APPENDIX + + + (p. 95). J. J. Thompson, D.Sc., LL.D., Ph.D., F.R.S.,etc., Electricity + and Matter, p. 75 ff., New York, 1904. The Silli-man Lectures, delivered + at Yale University, May, 1903. + + (p. 96). Ibid., pp. 88, 89. 3 (p- 97)- Ibid., p. 89. + + (p. 97). Ibid., p. 87. + + (p. 102). George F. Kunz, "Radium and its Wonders," in the Review of + Reviews for November, 1903, p. 589. + + (p. 105). E. Rutherford, Radio-Activity, p. 330, Cambridge, 1904. + + (p. 106). Ibid., p. 330. + + (p. 106). Compte Rendu, pp. 136, 673, Paris, 1903. + + (p. 106). Revue Scientifique, April 13, 1901. 10 (p. 106). Compte Rendu, + p. 136, Paris, 1903. + + + (p. 108). J. J. Thompson, Electricity and Matter, p. 162, New York, + 1904. + + (p. --). E. Rutherford, Radio-Activity, p. 340, Cambridge, 1904. + + (p. 185). Dr. Duclaux, who was one of Pasteur's chief assistants, and + who succeeded him in the directorship of the Institute, died in 1903. He + held a professorship in the University of Paris during the later years + of his life, and his special studies had to do largely with the chemical + side of bacteriology. + + (p. 217). Lord Kelvin's estimate as quoted was expressed to the writer + verbally. I do not know whether he has anywhere given a similar written + verdict. + + + +A LIST OF SOURCES + + +I.--PERIOD COVERED BY VOLUME I. + +An ax agoras. See vol. i., p. 240. + +Archimedes. See vol. i., p. 196. + +Many of the works of Archimedes are lost, but the following have come +down to us: (1) On the Sphere and Cylinder; (2) The Measure of the +Circle; (3) Conoids and Spheroids; (4) On Spirals; (5) Equiponderants +and Centres of Gravity; (6) The Quadrature of the Parabola; (7) On +Bodies Floating in Liquids; (8) The Psammites; (9) A Collection of +Lemmas. + +Aristarchus. See vol. i., p. 212. + +Magnitudes and Distances of the Sun and Moon is the only surviving work. +In the Armarius of Archimedes another work of Aristarchus is quoted--the +one in which he anticipates the discovery of Copernicus. Delambre, in +his Histoire de Vastronomie ancienne, treats fully the discoveries of +Aristarchus. + +Aristotle. See vol. i., p. 82. + +An edition of Aristotle was published by Aldus, Venice, 1495-1498, 5 +vols. During the following eighty years seven editions of the Greek text +of the entire works were published, and many Latin translations. + +Berosus. See vol. i., p. 58. + +The fragments of Berosus have been trans, by I. P. Cory, and included +in his Ancient Fragments of Phoenician, Chaldean, Egyptian, and Other +Writers, London, 1826; second edition, 1832. + +Democritus. See vol. i., p. 161. + +Fragments only of the numerous works ascribed to Democritus have been +preserved. Democriii Abdereo operum fragmenta, Berlin, 1843, edited by +F. G. A. Mullach. Diodorus Siculus. See vol. i., p. 77. + +The Historical Library. Perhaps the best available editions of Diodorus +are Wesseling's, 2 vols.; Amstel, 1745; and Dindorf's, 5 vols., Leipzig, +1828-1831. English trans, by Booth, London, 1700. Diogenes Laertius. See +vol. i., p. 121. + +The Lives and Opinions of Eminent Philosophers (trans. by C. D. Yonge), +London, 1853. + +Eratosthenes. See vol. i., p. 225. + +The fragments of his philosophical works were published at Berlin, 1822, +under the title Eratosthenica. His poetical works were published at +Leipzig, 1872. Euclid. See vol. i., p. 193. + +His Elements of Geometry is still available as an English school +text-book. + +Galen (Claudius Galenus). See vol. i., p. 272. + +Galen's preserved works are exceedingly bulky. The best-known edition is +that of C. G. Kuhn, in 21 volumes. + +Hero. See vol. i., p. 242. + +The Pneumatics of Hero of Alexandria, from the original Greek. Trans, by +B. Woodcroft, London, 1851. Herodotus. See vol. i.t p. 103. + +History. English trans, by Beloe, 1791 and 1806. Trans, by Canon +Rawlinson, London, 1858-1860. Hipparchus. See vol. i., p. 233. + +The only work of Hipparchus which has survived was published first by +Vittorius at Florence, 1567. Hippocrates. See vol. i., p. 170. + +Numerous editions have been published of the Hippo-cratic writings, +including many works not written by the master himself. One of the best +editions is that of Littre, Paris, 1839, etc. + +Khamurabi, Codb op. See vol. i., p. 76. + +This famous inscription is on a block of black diorite nearly eight feet +in height. It was discovered at Susa by the French expedition under M. +de Morgan in December, 1901. + +Leucippus. See vol. i., p. 161. + +Pliny (Caius Plinius Secundus). See vol. i., p. 265. + +His Natural History is available in several English editions and +reprints. Perhaps the best edition of the original text is the one +published by Julius Sillig, 5 vols., Leipzig, 1854-1859. Plutarch. See +vol. i., p. 198. + +Life of Marcellus, in Parallel Lives. In this the mechanical inventions +of Archimedes are described. Polybius. See vol. i., p. 201. + +In his Histories Polybius describes the mechanical contrivances and +war-engines of Archimedes, and also gives an account of his death. +Ptolbmy (Claudius Ptolemaeus). See vol. i., p. 269. + +Geographia (or Almagest of the Arabs). The edition published by Nobbe, +in 3 vols., Leipzig, 1842, was one of the best complete editions of the +Greek text. The edition published in Didot's Bibliotheca Classicorum +Grocorum, Paris, 1883, is excellent. Earlier editions contain many +errors. + +Strabo. See vol. i., p. 255. + +The Geography of Strabo. Trans, by H. C. Hamilton and W. Falconer, 3 +vols., London, 1857. There are several other editions of Strabo's work +available in English. + +Tertullian. See vol. i., p. 195. + +Apologeticus. Theophrastus. See vol. i., p. 188. + +Utpivlaroplas, On the History of Plants. Written in 10 books. +This is one of the earliest works on botany which have come to us. +It was largely used by Pliny. In complete works, Schneider, Leipzig, +1818-1821, 5 vols. On Plants, edited by Wimmer, Breslau, 247 + +1842-1862. On Plants, edited by Slackhouse, Oxford, 1814. +atria, On the Causes of Plants, This was originally in 8 books, of +which 6 are now existant. Bibliog. vid. History of Plants. + + + +II.--PERIOD COVERED BY VOLUME II. + +Albategnius, Mohammed bbn Jabir. See vol. ii., p. 15. + +The original MS. of his principal work, Zidje Sabt, is in the Vatican. A +Latin translation was first published by Plato Tiburtinus at Nuremberg, +in 1537, under the title De scientia stellarunt. Various reprints of +this have been made. Albertus Magnus. See vol. ii., p. 127. + +Philosophic* Naturalis Isagoge, Vienna, 1514. Alhazen (full name, Abu +Ali al-Hasan Ibn Alhasan). See vol. ii., p. 18. + +Only two of his works have been printed, his Treatise on Twilight +and his Thesaurus opticae, these being available in Michael Casiri's +Bibliotheca Arabico-Hispana Escuri-alensis, 2 vols., Madrid, 1760-1770. + +Bacon, Francis. See vol. ii., p. 192. + +Novum Organum was published in London, 1620. The Letters and Life of +Lard Bacon, in 7 vols., by James Spedding, appeared in 1862-1874. Bacon, +Roger. See vol. ii., p. 44. + +Only an approximate estimate of the number of Bacon's works can be given +even now, although an infinite amount of time and labor has been +spent in collecting them. His great work is the Opus ma jus, "the +Encyclopaedia and the Organum of the Thirteenth Century." A partial list +of some of his other works is the following: Speculum alchemio, 1541 +(trans, into English); De mirabili potestate artis et naturo, 1542 +(trans, into English, 1659); Libellus de retardants se-nectutis +accidentibus, 1590 (trans, as "The Cure of Old. Age," 1683); and +Sanioris medicino Magistri d. Rogeri Baconis Anglici de arte chymio +scripta, 1603. 248 + +Boyle, Robert. See vol. ii., p. 205. + +Philosophical Works, 3 vols., London, 1738. + +Copernicus, Nicolaus. See vol. ii., p. 54. + +Ad clar. v. d. Schonerum de libris revolutionism eruditiss. viri et +mathemattci excellentiss. Rev. Doctoris Nicolai Copernici Torunnaei, +Canonici Warmiensis, per quemdam juvenem mathematico studio sum, +Narratio prima, Dantzic, 1540. This was the first published statement +of the doctrine of Copernicus, and was a letter published by Rheticus. +Three years afterwards Copernicus's De orbium colestium revolutionibus, +Libri VI., was published at Nuremberg (1543). + +Descartes, Rene. See vol. ii., p. 193. + +Traite de Vhomme (Cousins's edition, in 11 vols., Paris, 1824). + +Galilei, Galileo. See vol. ii., p. 91. + +Dialogo dei due massimi sistemi del mondo, Florence, 1632. Discorsi e +dimostrazioni matematiche intorno a due nuove scienze, Leyden, 1638. +Gilbert, William (1540-1603). See vol. ii., p. 113. + +De magnete, magneticisque corporibus, et de magno magnete tellure, +London, 1600. De magnete was trans. by P. Fleury Motteley, London, 1893. +Guericke, Otto von (1620-1686). See vol. ii., p. 213. + +Experimenta nova, ut vocant, Magdeburgica de vacuo spatio, Amsterdam, +1672. In the Phil. Trans, of the Royal Society of London, No. 88, for +1672. + +Hales, Stephen (1677-1761). See vol. ii., p. 298. + +Statical Essays, comprising Vegetable Staticks, London, 1727, and +Homostatics, London, 1733. Harvey, William. See vol. ii., p. 169. + +Exercitatio anatomica de motu cordis et sanguinis, Frankfort-on-Main, +1628. The Works of, trans, by Robert Willis, London, 1847. Hauksbeb, +Francis. See vol. ii., p. 259. + +Physico-Mechanical Experiments on Various Subjects, London, 1709. This +contains descriptions of his various discoveries in electricity, many of +which are given in the Phil. Trans. + +Hooee, Robert. See vol. ii., p. 215. + +Micrographia, or Some Philosophical Descriptions of Some Minute Bodies, +London, 1665. An Attempt to Prove the Motion of the Earth, London, 1674. +Microscopical Observations, London, 1780. Most of Hooke's important +discoveries were contributed as papers to the Royal Society and are +available in the Phil. Trans. + +Huygens, Christian (1629-1695). See vol. ii., p. 218. + +Traite de la lumiere, Leyden, 1690. Complete works were published at +The Hague in 1888, under thetit le Ouvres completes, by the Societe +Hollandaise des Sciences. These books have not been translated into +English. Huygens's famous paper on the laws governing the collision of +elastic bodies appeared in the Phil. Trans, of the Royal Society for +1669. + +Kepler, Johann. See vol. ii., p. 70. + +Astronomia nova de motibus Stella Mortis, Leipzig, 1609, contains +Kepler's two first laws; and Harmonices mundi, 1619, contains the third +law, Phomomenon singulare, seu Mercurius in sole, Leipzig, 1609. Joannis +KepUri opera omnia, in 8 vols., Frankfort, 1858-1871. + +Leeuwenhoek, Anthony van. See vol. ii., p. 179. + +His discoveries are mostly recorded in the Phil. Trans. of the Royal +Society, between the years 1673 and 1723--one hundred and twelve papers +in all. His discovery of bacteria is recorded in Phil. Trans, for 1683; +and that of the discovery of the capillary circulation of the blood in +Phil. Trans, for 1790. + +LiNNiEus, Carolus (1707-1778). See vol. ii., p. 299. + +His Systema natures was published in 1735. Tro years later (1737) +he published Genera plantarum, which is generally considered as the +starting-point of modern botany. His published works amount to more than +one hundred and eighty. + +Mariotte, Edme (died 1684). See vol. ii., p. 210. + +Essais de physique (four essays), Paris, 1676-1679. 250 + +His De la nature de l'air, containing his statement of the law +connecting the volume and pressure of a gas, is contained in the second +essay. + +Newton, Sir Isaac. See vol. ii., p. 241. + +Philosophies naturalis principia mathematica, completed in July of +1687. The first edition was exhausted in a few months. There are several +translations, among others one by Andrew Motte, New York, 1848. + +Paracelsus. See vol. ii., p. 159. + +The Hermetic and Alchemical Writings of Paracelsus, trans, by A. E. +Waite, 2 vols., London, 1894. Pascal, Blaise. See vol. ii., p. 122. + +Recit de la grande experience de Vequilibre de liqueurs, Paris, 1648. + +Sawtree, John. See vol. ii., p. 124 ff. + +Of the Philosopher's Stone, London, 1652. Swammerdam, John. See vol. +ii., p. 297. + +Bibel der Natur, trans, into German, Leipzig, 1752. Sydenham, Thomas. +See vol. ii., p. 189. + +His first work, Methodus curandi febres, was published in 1666. His last +work, Processus integri, appeared in 1692. His complete works, in Latin, +were published by the Sydenham Society, London, 1844, which published +also an English translation by Pr. R. G. Latham in 1848. There are +several other English translations. + +Torricelli, Evanoelista. See vol. ii., p. 120. + +Opera geometrica, Florence, 1644. Tycho Brahe. See vol. ii., p. 65. + +De mundi aetherei recentioribus phonomenis, Prague, 1603. This has been +trans, into German by M. Bruns, Karlsruhe, 1894. + +Vinci, Leonardo da. See vol. ii., p. 47. + +Leonardo da Vinci, Artist, Thinker, and Man of Science, by Eugene Muntz, +2 vols., New York, 1892, is perhaps the most complete treatment of all +phases of Leonardo's work as a scientist as well as an artist. The older +French work, Essai sur les ouvrages physico-mathematiques de Leonard +de Vinci, by J. B. Venturi, Paris, 1797, is excellent. In German, H. +Grothe's Leonardo da Vinci als Ingenieur und Philosophy Berlin, 1874, is +good. + + + +III.--MODERN COSMICAL AND TELLURIC SCIENCES + +Agassiz, L. See vol. iii., p. 147. + +Etudes sur les glaciers, Neuchatel, 1840. Arago, Francois J. D. See vol. +Hi., p. 67. + +Ouvres (complete), if vols., Paris, 1854-1862. Arago's Meteorological +Essays, trans, into English, London, 1855. This has an introduction by +Humboldt. + +Boscovich, Roger Joseph. See vol. iii., p. 293. + +Theoria philosophio naturalis redacta ad unicam legem virium in natura +existentium, Vienna, 1758. Bradley, James. See vol. iii., p. 13. + +Concerning an Apparent Motion Observed in Sotne of the Fixed Stars, +London, 1748, Phil. Trans., vol. xlv., pp. 8,9. + +Cuvier,*Baron de. See vol. iv., p. 103. + +Recherches sur les ossements fossiles de quadrupedes, 4 vols., Paris, +1812. (The introduction to this work was translated and published as a +volume bearing title of Theory of the Earth, New York, 1818.) + +Delambre, Jean Baptiste Joseph. See vol. iii., p. 16. + +Histoire d'astronomie, Paris, 1817-1821. This work contains not only +the history of the discoveries in astronomy, but is also a complete +text-book of astronomy as understood at this period. + +Falconer, Hugh. See vol. iii., p. 99. + +In Paloontological Memoirs, vol. ii., pp. 596-598. 252 + +Herschbl, William. See vol. iii., p. 20 ff. + +On the Proper Motion of the Solar System, Phil. Trans., vol. 73, for +1783. (This paper was read in March, 1783.) The Constitution of the +Heavens, Phil. Trans, for 1785, vol. 75, p. 213. Howard, Luke. See vol. +iii., p. 182. + +Philosophical Magazine, 1803. Humboldt, Alexander von. See vol. iii., p. +192. + +Des lignes isothermes et de la distribution de la chaleur sur le globe, +published in vol. iii., of Memoires de physique et de chimie de la +Societe d'Arcueil, Paris, 1819. Hutton, James. See vol. iii., p. 178. + +Theory of Rain, in Transactions of the Royal Society of Edinburgh, 1788, +vol. i., pp. 53-56. See vol. iii., p. 121. From Transactions of the +Royal Society of Edinburgh, 1788, vol. i., pp. 214-304. A paper on the +"Theory of the Earth," read before the society in 1781. + +Kant, Immanuel (i724-1804). See vol. iii., p. 27. + +Allgemeine Naturgeschichte und Theorie des Himmels, 1755. Cosmogony, ed. +and trans, by W. Hartie, D.D., Glasgow, 1900. + +Laplace, M. le Marquis de. See vol. iii., p. 32. + +Exposition du systeme du monde, Paris, 1796, is available in Ouvres +completes, in 12 vols., Paris, 1825-1833^01. vi., p. 498. Lyell, +Charles. See vol. iii., p. 88. + +Principles of Geology, 4 vols., London, 1834. + +Marsh, O. C. See vol. Hi., p. 107. + +Fossil Horses in America (reprinted from American Naturalist, vol. +viii., May, 1874), pp. 288, 289. + +Playpair, John. See vol. iii., pp. 131, 165. + +Illustrations of the Huttonian Theory, 1802. + +Scrope, G. Poulett. See vol. iii., p. 132. + +Consideration of Volcanoes, London, 1823, pp. 228-234. + +Wells, W. C. See vol. iii., p. 185. Essay on Dew, London, 1818. + + + + +IV.--MODERN PHYSICAL AND CHEMICAL SCIENCES + +Black, Joseph. See vol. iv., p. 12. + +De acido e cibis orlo, et de magnesia, reprinted at Edinburgh, 1854. In +this he sketched his discovery of carbonic acid. Later this paper +was incorporated in his Experiments on Magnesia, Quicklime, and Other +Alkaltne Substances. + +Bunsen, William. See vol. iv., p. 69. + +Cavendish, Henry. See vol. iv., p. 15. + +"Experiments on Air," in Phil. Trans., 1784, p. 119. This paper contains +Cavendish's discovery of the composition of water and of nitric acid. + +Daguerre, Louis J. M. See vol. iv., p. 70. + +Historique et description des procedes du daguerreotype et du diorama, +Paris, 1839. (This was translated into English.) + +Dalton, John. See vol. iv., p. 40. + +"On the Absorption of Gases by Water," read before the Literary +and Philosophical Society of Manchester, October 21, 1803. This +was published in 1805, and contains the atomic weight of twenty-one +substances, some of which were probably added, or corrected, between the +date of the first reading and the publication. + +Davy, Sir Humphry. See vol. iv., pp. 48, 209. + +"Some Chemical Agencies of Electricity," in Phil. Trans, for 1806, vol. +viii. Researches, Chemical and Philosophical, chiefly concerning Nitrous +Oxide or De-phlogisticated Nitrous Air and its Respiration, London, +1800. + +Dewar, James. See vol. v., p. 39. + +"Solid Hydrogen," in Proc. Roy. Inst, for 1900. "The Nadir of +Temperature and Allied Problems " (Bakerian Lecture), Proc. Roy. Soc, +1901. + +Dufay, Cisternay. See vol. ii., p. 267. + +Histoire de l'Academie Royale des Sciences, between 1733 and 1737, +contains Dufay's principal papers. + +Eulbr, Leonard (1707-1783). See vol. iii., p. 17. + +Lettres a une Princesse d'Allemagne sur quelques sujets de physique et +de philosophie, St. Petersburg, 1768. + +Faraday, Michael. See vol. iii., p. 241. + +On the Induction of Electric Currents, in Phil. Trans. of Royal Society +for 1832, pp. 126-128. Explication of Arago's Magnetic Phenomena, by +Michael Faraday, F.R.S., Phil. Trans, of Royal Society for 1832, pp. +146-149. Franklin, Benjamin. See vol. ii., p. 286. + +New Experiments and Observations on Electricity, London, 1760. + +Galvani, Luigi (1737-1798). See vol. iii., p. 229. + +De viribus electricitatis in motu musculari commentatio, Bologna, 1791. +This discovery of Galvani was first brought to notice by Volta's famous +paper to the Royal Society, entitled "An Account of some Discoveries +made by Mr. Galvani, of Bologna," published in the Phil. Trans, for +1793, pp. 10-44. + +Gay-Lussac, Joseph Louis. See vol. iv., p. 41. + +Memoire sur la combinaison des substances gazeuses, Mem. Soc. d'Arcueil, +1809. + +Halley, Edmund. See vol. iii., p. 7. + +An Account of Several Extraordinary Meteors or Lights in the Sky, in +Phil. Trans., vol. xxix., pp. 159-162, London, 1714. Helmholtz, H. L. F. +See vol. iii., p. 280. + +Handbuch der physiologische Optik, Leipzig, 1867. + +Joule, J. P. See vol. iii., p. 269. + +On the Calorific Effects of Magneto-Electricity and the Mechanical Value +of Heat, in Report of the British Association for the Advancement of +Science, 1843, vol. xii" p. 33- + +Kirwan, R. See vol. iv., p. 3 ff. + +An Essay on Phlogiston and the Constitution of Acids, London, 1789. +This is interesting, written as it was just before Lavoisier's Elements +treated the same subject from the stand-point of the anti-phlogistic +chemists. + +Kleist, Dean von. See vol. ii., p. 280. + +In the Danzick Memoirs, vol. i. contains the description given by Von +Kleist of his discovery of the Leyden jar. A translation is given also +in Priestley's History of Electricity. + +Lavoisier, Antoine Laurent. See vol. iv., p. 33. + +Traite elementaire de chimie, Paris, 1774, trans, as Elements of +Chemistry, by Robert Kerr, London and Edinburgh, 1790. Lister, Joseph +Jackson. See vol. iv., p. 113. + +On Some Properties in Achromatic Object Glasses Applicable to the +Improvement of the Microscope, in Phil. Trans, for 1830. + +Maxwell, James Clerk-. See vol. iii., p. 45. + +" On the Motions and Collisions of Perfectly Elastic Spheres " in +Philosophical Magazine for January and July, i860. The Scientific Papers +of J. Clerk-Maxwell, edited by W. D. Nevin (2 vols.), vol. i., pp. +372-374, Cambridge, 1896. This is a reprint of Maxwell's prize paper of +1859. Mayer, Dr. Julius Robert. See vol. iii., p. 259. + +The Forces of Inorganic Nature, 1842. This is Mayer's statement of the +conservation of energy. Mendeleepp, Dmitri Ivanovitch. See vol. iv., p. +68. + +Principles of Chemistry, 2 vols., London, 1868-1870. (There have been +several subsequent editions.) + +Oersted, Hans Christian. See vol. iii., p. 236. + +Experiments with the Effects of the Electric Current on the Magnetic +Needle, published at Berlin, 1816. + +Priestley, Joseph. See vol. iv., pp. 20, 36. + +Experiments and Observations on Different Kinds of Air, 3 vols., +Birmingham, 1790. History of Electricity, 256 vol. ii., p. 280, London, +1775. The Doctrine of Phlogiston Established, 1800. + +Ramsay and Ravlbigh. See vol. v., p. 86. + +"On an Anomaly Encountered in Determining the Density of Nitrogen Gas," +in Proc. Roy. Soc, April, 1894. A statement of the properties of argon +was made by the discoverers to the Royal Society, given in Phil. Trans., +clxxxvi., p. 187, January, 1895. + +ScHBBLB, Karl William. See vol. iv., p. 23. + +Om Brunsten, eller Magnesia, och dess Egenakaper, Stockholm,1774. This +contains his discovery of chlorine. His book, Chemische Abhandlung von +der Luft und dent Feuer, was published in 1777. + +Thompson, Benjamin (Count Rumford). See vol. iii., p. 208. Essays +Political, Economical, and Philosophical (2 vols.), vol. ii., pp. +470-493, London, T. Cadell, Jr., and W. Davies, 1797. Thomson, William +(Lord Kelvin). See vol. iii., p. 276. + +On a Universal Tendency in Nature to the Dissipation of Mechanical +Energy, in Transactions of the Royal Society of Edinburgh, 1852. + +Wollaston, William Hyde. See vol. iv., p. 41. + +Phil. Trans, for 1814, vol. civ., p. i, contains a synoptic scale of +chemical equivalents. This paper was confirmatory of Dalton's theory. + +Young, Thomas. See vol. iii., p. 218. + +On the Colors of Thin Plates" I.e. in Phil. Trans, for 1802, pp. 35-37. + + + +V.--MODERN BIOLOGICAL SCIENCES + +Avenbruggbr, Lbopold. See vol. iv., p. 200. + +Inventum novum ex percussione thoracis humant interni pectoris morbos +detegendi, Vienna, 1761. vot. V.-17 257 + +Bell, Sir Charles See vol. iv., p. 249. + +An Exposition of the Natural System of Nerves of the Human Body, being +a Republication of the Papers delivered to the Royal Society on the +Subject of the Nerves in 1811, etc. + +Bernard, Claude. See vol. iv., p. 137. + +BOERHAAVB, HERMANN. See Vol. IV., p. 182. + +Institutions medicos, Leyden, 1708; and De chemie expurgante suos +errores, Lugduni Batavorum, 1718. Brown, Robert. See vol. iv., p. 115. + +On the Organs and Mode of Fecundation of Orchideo and Asclepiadeo, in +Miscellaneous Botanical Works, London, 1866. + +Chambers, Robert. See vol. iv., p. 161. + +Vestiges of the Natural History of Creation, London, 1844 (published +anonymously). His Sequel to Vestiges was published a year later. +Charcot, Jean Martin. See vol. iv., p. 269. + +Lecons sur Us maladies du systeme nerveux, Paris, beginning in 1873. +Cuvier, George, Baron de. See vol. iv., p. 159. + +Histoire naturelle des animaux sans vertebres, Paris, 1815. Systeme des +connaissances positives de Vhomme, Paris, 1820. + +Darwin, Erasmus. See vol. iv., pp. 94, 147. + +The Botanic Garden, London, 1799. The Temple of Nature, or The Origin +of Society, edition published in London, 1807. Darwin, Charles. See vol. +iii., p. 95, and vol. iv., p. 173. The Origin of Species, London, 1859. + +Pechner, Gustav. See vol. iv., p. 263. Elemente du Psychophysik, i860. +Flourens, Marie Jean Pierre. See vol. iv., p. 270. + +Experiences sur le systeme nerveux, Paris, 1825. Cours sur la +generation, Vovologie, et Vembryologie, Paris, 1836, etc. + +Gall, Franz Joseph. See vol. iv., p. 248. + +Recherches sur le systeme nerveux en general, et sur celui du cerveau en +particulier, Paris, 1809. (This paper was laid before the Institute of +France in March, 1808.) Goethe, Johann Wolfgang. See vol. iv., p. 140. + +Die Metamorphose der Pflanzen, 1790. Gray, Stephen. See vol. ii.t p. +262. + +Most of his original papers appeared in the PhU. Trans, between 1720 and +1737. + +Haeckel, Ernst Heinrich. See vol. v., p. 144. + +Naturlich Schopfungsgeschichte, 1866, rewritten in a more popular +style two years later as Natural History of Creation. Some of his more +important monographs are: Radiolaria (1862), Siphonophora (1869), +Monera (1870), Calcarious Sponges (1872), Arabian Corals (1876), another +Radiolaria, enumerating several thousand new species, accompanied by one +hundred and forty plates (1887), and Die Weltrathsel, trans, in 1900 +as The Riddle of the Universe. Hahnemann, Wilhelm von. See vol. iv., p. +189. + +Organon der rationellen Heilkunde, Dresden, 1810. Hall, Marshall, M.D., +F.R.S.L. See vol. iv., p. 251. + +On the Reflex Functions of the Medulla Oblongata and the Medulla +Spinalis, in Phil. Trans, of Royal Society, vol. xxxiii., 1833. Hunter, +John. See vol. iv., p. 92. + +On the Digestion of the Stomach after Death, first edition, pp. 183-188. + +Jenner, Edward. See vol. iv., p. 190. + +An Inquiry into the Causes and Effects of the Variolo Vaccino, London, +1799. + +Laennec, Rene Theophile Hyacinthe. See vol. iv., p. 201. + +Traite d'auscultation mediate, Paris, 1819. Lamarck, Jean Baptiste de. +See vol. iv., p. 152. + +Philosophie zoologique, 8 vols., Paris, 1801. His famous statement of +the supposed origin of species occurs on p. 235 of vol. i., as follows: +"Everything which nature has caused individuals to acquire or lose by +the influence of the circumstance to which their race is long exposed, +and consequently by the influence of the predominant employment of such +organ, or its constant disuse, she preserves by generation to the new +individuals proceeding from them, provided that the changes are +common to the two sexes, or to those which have produced these new +individuals." + +Libbig, Justin. See vol. iv., p. 131. + +Animal Chemistry, London, 1843. + +Libbig and Wohler. See vol. iv., p. 56. + +The important work of Liebig and Wohler appeared until 183a mostly in +Poggendorff's Armalen, but after 1832 most of Liebig's work appeared in +his own Annalen. About the earliest as well as one of his most important +separate works is Anleitung zur Analyse organischen, Korper, 1837. + +Lotze, Hermann. See vol. iv., p. 263. + +Medizinische Psychologie, oder Physiologie der Seele, Leipzig, 1852. + +Mohl, Hugo von. See vol. iv., p. 125. + +Uber der Saftbewegung im Innern d. Zelle, Bot. Zei-tung, 1846. Morgagni, +Giovanni Battista. See vol. iv., p. 76. + +De sedibus et causis ntorborum, 2 vols., Venice, 1761. + +Oken, Lorenz. See vol. iv., p. 160. + +Philosophie der Natur, Zurich, 1802. + +Pasteur, Louis. See vol. iv., pp. 217, 233. + +Studies on Fermentation, London, 1879. His famous paper on attenuation +and inoculation was published in the Compte Rendu of the Academy of +Science, Paris, 1881 (vol. xcii.). + +Saint-Hilaire, Etienne Geoffroy. See vol. iv., p. 160. + +Philosophie anatomique, vol. i., Paris, 1818. Schwann, Theodor. See vol. +iv., p. 119. + +Mikroskopische Untersuchungen uber die Ubereinstim-mung in der Structur +und dem Wachsthum der Thiere und Pflanzen, Berlin, 1839. Trans, by +Sydenham Soc., 1847. Spencer, Herbert. See vol. iv., p. 268. + +Principles of Psychology, London, 1855. 260 + +Treviranus, Gottfried Reinhold. See vol. iv.t p. 159. Biologie, oder +Philosophie der lebenden Natur, 1802. + +Weber, E. H. See vol. iv., p. 263. + +The statement of "Weber's Law*' was first made in articles by Weber +contributed to Wagner's Handwarter-buch der Physiologie, but is +again stated and elaborated in Fechner's Psychophysik. (See Fechner.) +Weismann, August. See vol. iv., p. 179. + +Studies in the Theories of Descent. Trans, by Professor R. Meldola, +London, 1882. The introduction to this work was written by Darwin. +Wohler, Friedrich. ' (See Liebig and Wohler.) Wundt, Wilhelm Max. See +vol. iv., p. 268. + +Grundzuge der physiologischen Psychologie, 1874. Many articles by Wundt +have appeared in the Philosophische Studien, published at Leipzig. + + + +V.--ASTRONOMY + +Astronomische G es disc haft. + +A quarterly journal of astronomy published in Leipzig. + +Berry, Arthur. + +A Short History of Astronomy, New York, 1899. Bertrand, J. L. F. + +Les fondateurs de Vastronomie modern: Copernic, Tycho Brake, Kepler, +Galileo, et Newton, Paris, 1865. This gives an interesting account of +the lives and works of these philosophers. + +Flammarion, C. + +Vie de Copernic, et histoire de la decouverte du systeme du monde, +Paris, 1872. Forster, W. + +Johann Kepler und die Harmonie der Sphcren, Berlin, 1862. + +Jensen, P. + +Die Kosmologie der Babylonier, Strasburg, 1890. 261 + +Lockyer, Joseph Norman. + +The Dawn of Astronomy; a Study of the Temple Worship and Mythology of +the Ancient Egyptians, London, 1894. Loom is. + +History of Astronomy, New York, 1855. + +Rothmann. + +History of Astronomy (in the Library of Useful Knowledge), London, 1834. + +Societe Astronomique de France. Monthly bulletin, Paris. + +Thompson, R. Campbell. + +Reports of the Magicians and Astrologers of Nineveh and Babylon, p. 19, +London, 1900. + +Wolf, R. + +Geschichte der Astronomie, Munich, 1877. + + + +VI.--PHYSICS (ELECTRICITY) + +Annalen der Physik, Leipzig. Edited by Dr. Paul Drude. (Note--Heavy, +scientific, up-to-date. Is apparently under the patronage of all the big +physicists, such as Roentgen, etc.) + +A tit della Associazione Elethotecnica Italiana (at Rome). A large +bi-monthly magazine, strictly technical, devoted largely to theoretical +problems of electricity and allied subjects. + +Bulletin International de VElectricite et Journal de VElectricite +{reunis). A semi-monthly four-page paper dealing with the technical +application of electricity in its various fields. + +Die Dissozuerung und Umwandlung chemischer Atome, by Dr. Johannes Stark, +1903. Price 150 m. "A comprehensive view of the application of the +electron theory to certain phenomena."--Nature, May, 1904. + +Die Kathodenstrahlen, by G. C. Schmidt, Brunswick, 1904. + +"A concise and complete account of the properties of the cathode +rays."--Nature, June, 1904. + +Electrical Engineer. + +Electrical Magazine. + +Electricity. A weekly journal, published by the Electricity Newspaper +Co., New York. Devoted largely to questions of the practical application +of electricity, but dealing also with the theoretical side. + +Elements of Electro-magnetic Theory, by S. J. Barnett, Le-land Stanford, +Junior, University. Macmillan & Co., 1904. + +($3.) + +Handbuch der Physik, by Dr. A. Winkelmann, Leipzig, 1904. "An +indispensable storehouse of expert knowledge."--Nature, July, 1904. + +Hardin. + +Rise and Development of the Liquefaction of Gases, New York, 1899. + +La theorie de Maxwell et les oscillations hertziennes, la Telegraphie +sans flt by H. Poincare, Paris, 1904 (price 2 fr.). Interesting studies +of light, etc. An interesting brochure.--Revue Scientifique, July, 1904. + +Le radium et la radioactivite, by Paul Besson, Paris, 1904 (price 2 +fr. 75). A good exposition of the known properties of radium, marred, +however, by an attempt to put in accord science and religion--a propos +du radium! --Revue Scientifique, July, 1904. + +Lehrbuch der Physik, by Von O. D. Chwolson, St. Petersburg, 1904. 2 +vols. out. First vol. covers general physics and mechanics. Second vol. +sound and radiant energy. "Excellent and quite comprehensive."--Science, +review. + +Park, Benjamin. + +The Intellectual Rise in Electricity, New York, 1895. This is a popular +account of the progress in the field of electricity from Gilbert to +Franklin. + +Radium and all About It, by S. Bottone, London, 1904. Published by +Whittaker & Co. Price is. "An accurate account of the most important +phenomena."--Nature, June, 1904. + +The Physical Review. A monthly journal of experimental and theoretical +physics. Published for Cornell University by the Macmillan Company. 263 + +Theory of Heat, by Thomas Preston, F.R.S. Second edition just out. +Macmillan & Co., 185. + + + +VII.-CHEMISTRY + +American Chemical Journal. Edited by Ira Remsen, president of Johns +Hopkins University. Published monthly at Baltimore, Maryland. Price $5 +per annum. A strictly technical journal. + +Bacon, Roger. + +Mirror of Alchemy, and Admirable Power of Art and Nature, London, 1597. + +Berthblot, P. E. M. + +Introduction a l'etude de la chimie des anciens et du moyen age, Paris, +1889. + +Les origines de l'alchimie, Paris, 1885. + +Bulletin de la Societe Chimique de Paris. A monthly technical journal, +treating all phases of the science of chemistry. + +Food Inspection and Analysis, by Albert E. Leach, S. B. (John Wiley & +Sons, N. Y., $7.50). Note. --This book is designed for the use of public +analysts, health officers, food economists, etc. + +Hoefer, J. C. F. + +Histoire de la chimie, Paris, 1866-1869. This gives biographical +sketches of many of the great chemists as well as the history of the +development of chemistry. + +Jahresbericht uber die Fortschritte der Chemie. A journal of the +progress in chemistry, published irregularly in Brunswick. + +Kopp, H. + +Geschichte der Chemie (4 vols.), Brunswick, 1843-1847. This is an +exhaustive history of the development of chemistry. + +Lehrbuch der Stereochemie, by A. Werner, Jena, 1904, price 10 m. "Should +be in the hands of every organic chemist."--Nature for August, 1904. + +Lemoine, Y. F. + +La vitalism et l'aminisme de Stahl, Paris, 1864. This discusses fully +Stahl's famous theories of matter and life. Meyer, E. von. + +A History of Chemistry from the Earliest Times to the Present Day, +London, 1898. This treats fully the subject of the phlogiston theory and +its influence in the development of chemistry. Muir, M. P. + +Story of Alchemy and the Beginnings of Chemistry, London and New York, +1899. A popular account of the development of the phlogiston theory +from alchemy, giving explanations of the curious beliefs and methods of +working of the alchemists. Rodwell, G. F. + +The Birth of Chemistry, London, 1874. Thompson, C. J. S. + +The Mystery and Romance of Alchemy and Pharmacy, in the Scientific +Press, London, 1897. This is very interesting and readable. Thompson, T. + +The History of Chemistry, London, 1830, 1831. Waite, Arthur Edward. + +Lives of Alchemisttcal Philosophers, London, 1888. A biographical +account of the most noted alchemists. This is very complete. Waite has +also collected a list of the principal works of the alchemists, this +list filling about thirty pages of fine print. + + + +VIII.--GEOLOGY. BIOLOGY, PALEONTOLOGY + +American Geologist. + +American Museum of Natural History Bulletins, New York. + +A merican Naturalist. + +Annales de l'Institut Pasteur (18 fr. per annum). A monthly bulletin of +the Pasteur Institute, containing mostly technical articles, but also +articles of interest to persons interested in problems of immunization +and immune sera. + +Annales des sciences naturelles: zoologie et paleontologie, Paris. + +Annals and Magazine of Natural History, including zoology, botany, and +geology. Monthly. London. A technical magazine. Of little interest to +the general reader. + +Archiv fur Naturgeschichte. A journal of natural history published +bi-monthly at Berlin. + +Archiv fur Rassen-und--Gesellschaft--Biologie einschliefslich +Rassen--und Gesell.-Hygiene. + +Archives de biologie (quarterly), Liege. + +Archives des sciences biologiques. St. Petersburg. Five numbers a year. + +Archives Italiennes de biologie. Turin. Bi-monthly. + +Biological Bulletin of the Marine Biological Laboratory, Wood's Holl, +Massachusetts. Published monthly by the laboratory. Managing editor, +Prank R. Lillie. Scientific and technical--very good. + +Biologie generale des bacteries, by E. Bodin, professor of bacteriology, +University of Rennes, Paris, 1904. Price 2 It. 50. Studies of bacteria +in general treated in a semi-popular manner. Some new ideas prepared to +explain bacterial action in normal life--very good.--Revue Scientifique, +review, August, 1904. + +Biometrika. A journal for the statistical study of biological problems +(quarterly), 305. per annum. Edited, in consultation with Francis +Galton, by W. F. R. Weldon, Karl Pearson, and C. B. Davenport. A bulky +journal, beautifully illustrated with plates and line cuts. Largely +technical, but containing many articles of interest to general readers +on laws of inheritance, hereditary influences, etc. + +Bulletin of the Geological Society of America. Published irregularly at +Rochester. + +Gcologische und Paloontologische Abhandlungen, Jena. + +Johns Hopkins University, Memoirs from the Biological ^ Laboratory. + +L'Echange Revue Linnienne, fondee par le Docteur Jacquet. Directeur, +M. Pic. A monthly journal of natural history, devoted largely to +entomology--small and technical. Of interest to entomologists only. + +Les lois naturelles, par Felix le Danteg, charge du cours d'embryologie +generale a la Sorbonne, Paris, 1904. Price 6 fr. A study in biology. +"The name corresponds exactly with the contents of this admirable +work."--Revue Scientifique, review, September, 1904. + +Marine Biological Association of the United Kingdom, Plymouth. + +Societe Dauphinoise d'Ethnologie et d'Anthropologie. Quarterly bulletin. +Grenoble. + +Societe Zoologique de France. Monthly bulletin. + +Text-book of Geology, by Sir Archibald Geikie, a vols. Fourth edition. +$10. Macmillan & Co., 1904. + +Text-book of Paleontology (Macmillan, 1904, $3), by Carl A. von Zittel, +University of Michigan. + +The Geological Magazine, or Monthly Journal of Geology, edited by Henry +Woodward, LL.D., F.R.S., etc. London, 15. ed. per copy. A high-class +technical magazine. + +The American Journal of Psychology, edited by G. Stanley Hall, E. C. +Sanford, and E. B. Titchnener. Published at Worcester, Massachusetts, +monthly. A technical journal devoted to psychological researches. + +The Naturalist, London. A monthly journal for the north of England. +Edited by J. Sheppard, P.G.S., and T. W. Woodhead, F.L.S. Annual +subscription, 65. 6d. A local journal, but containing general articles +of interest. Semi-popular. + +The Quarterly Journal of Microscopical Science, edited by E. Ray +Lankester, M.A., LL.D., F.R.S. + + + +IX.--MEDICINE + +American Journal of Insanity. + +American Journal of the Medical Sciences, Philadelphia. + +Annales medico-psychologiques, Paris. + +Arbeiten aus dem leaiserlichen Gesundheitsamte. A journal of hygiene +published irregularly at Berlin. + +Archiv fur Anatomie und Physiologic. A semi-monthly journal of the +progress in anatomy and physiology, published at Leipzig. + +Archiv fur die gesammte Physiologie, Bonn. + +British Medical Journal, London. + +Immune Sera, by Professor A. Wassermann, M.D., trans, by Charles +Bolduan, M.D., New York and London, 1904. "We confidently commend this +little book to all persons desirous of acquainting themselves with the +essential facts on the subject of immune sera."--Nature, July, 1904. + +Lancet, London. + +Leclerc, Lucien. + +Histoire de la medecine arabe, 2 vols., Paris, 1876. This work is very +complete and well written. + +Medical Record, New York. + +Medical Times, New York. + +Pagel, Julius. + +Einfuhrung in die Geschichte der Medicin, Berlin, 1898. This is not as +exhaustive as Baas's book, but is written in a much more readable style. + +Park, Roswell. + +Epitome of thf History of Medicine, Philadelphia, 1899. + +Paul of AEgina. + +The Works of, published by the Sydenham Society, London, 1841, are well +worth reading, as giving a clear understanding of the status of medicine +in the seventh century. + +Sprengal, K. P. J. + +Histoire de la medecine depuis son origine jusqu'au dix-neuvieme siecle, +8 vols., Paris, 1815-1820. This is a French translation of the German +work, and is more available than the original volumes. It is, perhaps, +the most exhaustive history of medicine ever attempted. + +The Journal of Hygiene, edited by George H. F. Nuttall, M.D., Ph.D. +A quarterly journal of hygiene (2 is. per annum), containing many +interesting articles on subjects connected with hygiene and of interest +to general readers. + +The Journal of Physiology, edited by Sir Michael Foster, K.C.B., M.D., +F.R.S., and J. N. Langley, Sc.D., F.R.S. Issued quarterly. Price Ss. C. +J. Clay & Sons, London. + + + +X.--ANTHROPOLOGY AND ARCHAEOLOGY + +American Anthropologist. F. W. Hodge, editor, Washington, D. C. +Published quarterly for the American Anthropological Association ($4.50 +per annum). Technical (or semi-technical). "A medium of communication +between students of all branches of anthropology." Much space devoted +to Indian language, etc.--;a very good journal. American Journal of +Archoology. American Journal of Sociology. + +Archivo per V antropologia e V etnologia, Florence. Three numbers a +year. A journal devoted to anthropology and ethnology. Avebury, Lord +(Sir John Lubbock). + +The Origin of Civilization and the Primitive Condition of Man. Mental +and social condition of modern savages. New York, 1870. Brinton, Daniel +Garrison, M.D. + +The Basis of Social Relation, a Study in Ethnic Psycliol-ogy, edited by +L. Farrand, New York, 1902. Clodd, Edward. + +Myths and Dreams, London. 1885. Story of Primitive Man, 3d edition, +London, 1897. The Childhood, of tlte World. A simple account of man in +early times. London, 1893. Dawkins, W. Boyd. + +Early Man in Britain, London, 1880. Cave Hunting. Researches on the +evidence of caves respecting the early inhabitants of Europe. London, +1874. Dellenbaugh, Frederick S. + +The North Americans of Yesterday, New York, 1901. Deniker, Joseph. + +Races of Man. An outline of anthropology and ethnology. London, 1900. +Grierson, P. J. H. Hamilton. + +The Silent Trade. A contribution to the early history of human +intercourse. London, 1903. Haeckel, Dr. Ernst Heinrich. + +Anthropogenic; oder Entwickelungsgeschichtc des Men-schen, 4th edition, +2 vols., Leipzig, 1891. 269 + +Mueller, Friedrich. + +Ethnographie; auf Grund des von K. von Scherzer gesammetten Materials. +Vienna, 1868. + +Murtillbt, Gabriel de. + +Le prehistorique antiquite de Vhomme. Paris, 1883. + +Powell, John Wesley. + +"Relation of Primitive Peoples to Environment." In Smithsonian +Institution Report. Washington, 1896. Reports of American Ethnology, in +the annual reports of the U. S. Bureau of Ethnology since 1877. + +Quatrepages (A. de Q. de Brun). + +Histoire generale des races humaines. Paris, 1889. + +Ratzel, Friedrich. + +The History of Mankind, 3 vols., trans, by A. J. Bubler, London, +1896-1898. + +Revue de l'Ecole d'Anthropologie de Paris. Monthly. Published by the +professors. Treats all phases and branches of anthropology. + +Science de l'homme et methode anthropologique, by Alphonse Cels, Paris +and Brussels, 1904. 7 francs. "As a highly abstract and suggestive +exposition of the nature and scope of anthropology, this book deserves +a place in the library of the anthropologist."--Nature, September 24, +1904. + +Societe Academique d'Archeologie, Paris. + + + + + + +End of the Project Gutenberg EBook of A History of Science, Volume 5(of 5), by +Henry Smith Williams + +*** END OF THIS PROJECT GUTENBERG EBOOK HISTORY OF SCIENCE, V5 *** + +***** This file should be named 30495.txt or 30495.zip ***** +This and all associated files of various formats will be found in: + http://www.gutenberg.org/3/0/4/9/30495/ + +Produced by David Widger + +Updated editions will replace the previous one--the old editions +will be renamed. + +Creating the works from public domain print editions means that no +one owns a United States copyright in these works, so the Foundation +(and you!) can copy and distribute it in the United States without +permission and without paying copyright royalties. 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