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| author | nfenwick <nfenwick@pglaf.org> | 2025-01-21 19:40:09 -0800 |
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| committer | nfenwick <nfenwick@pglaf.org> | 2025-01-21 19:40:09 -0800 |
| commit | 3e1ed94196ba7b3a987117dfd329fa950f1e7efb (patch) | |
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| parent | c2269ed51b95adf3d9e25092118d947aa4c72bf3 (diff) | |
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diff --git a/.gitattributes b/.gitattributes new file mode 100644 index 0000000..d7b82bc --- /dev/null +++ b/.gitattributes @@ -0,0 +1,4 @@ +*.txt text eol=lf +*.htm text eol=lf +*.html text eol=lf +*.md text eol=lf diff --git a/LICENSE.txt b/LICENSE.txt new file mode 100644 index 0000000..6312041 --- /dev/null +++ b/LICENSE.txt @@ -0,0 +1,11 @@ +This eBook, including all associated images, markup, improvements, +metadata, and any other content or labor, has been confirmed to be +in the PUBLIC DOMAIN IN THE UNITED STATES. + +Procedures for determining public domain status are described in +the "Copyright How-To" at https://www.gutenberg.org. + +No investigation has been made concerning possible copyrights in +jurisdictions other than the United States. Anyone seeking to utilize +this eBook outside of the United States should confirm copyright +status under the laws that apply to them. diff --git a/README.md b/README.md new file mode 100644 index 0000000..4999e61 --- /dev/null +++ b/README.md @@ -0,0 +1,2 @@ +Project Gutenberg (https://www.gutenberg.org) public repository for +eBook #68326 (https://www.gutenberg.org/ebooks/68326) diff --git a/old/68326-0.txt b/old/68326-0.txt deleted file mode 100644 index b82fc85..0000000 --- a/old/68326-0.txt +++ /dev/null @@ -1,3848 +0,0 @@ -The Project Gutenberg eBook of History of electric light, by Henry -Schroeder - -This eBook is for the use of anyone anywhere in the United States and -most other parts of the world 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. If you are not located in the United States, you -will have to check the laws of the country where you are located before -using this eBook. - -Title: History of electric light - -Author: Henry Schroeder - -Release Date: June 16, 2022 [eBook #68326] - -Language: English - -Produced by: Charlene Taylor, Charlie Howard, and the Online Distributed - Proofreading Team at https://www.pgdp.net (This file was - produced from images generously made available by The - Internet Archive/American Libraries.) - -*** START OF THE PROJECT GUTENBERG EBOOK HISTORY OF ELECTRIC -LIGHT *** - - - - - -Transcriber’s Notes - - -In this Plain Text version of this eBook, italics are enclosed within -~tildas~, superscripts and subscripts are enclosed in curly braces and -preceded by a caret ^{superscript} or an underscore _{subscript}. - -Other notes will be found at the end of this eBook. - - - - - SMITHSONIAN MISCELLANEOUS COLLECTIONS - VOLUME 76, NUMBER 2 - - - HISTORY OF ELECTRIC LIGHT - - - BY - HENRY SCHROEDER - Harrison, New Jersey - - [Illustration: FOR THE INCREASE - AND DIFFVSION OF - KNOWLEDGE AMONG MEN - - SMITHSONIAN - INSTITVTION - WASHINGTON 1846] - - (PUBLICATION 2717) - - - CITY OF WASHINGTON - PUBLISHED BY THE SMITHSONIAN INSTITUTION - AUGUST 15, 1923 - - - - - The Lord Baltimore Press - BALTIMORE, MD., U. S. A. - - - - -CONTENTS - - - PAGE - - List of Illustrations v - - Foreword ix - - Chronology of Electric Light xi - - Early Records of Electricity and Magnetism 1 - - Machines Generating Electricity by Friction 2 - - The Leyden Jar 3 - - Electricity Generated by Chemical Means 3 - - Improvement of Volta’s Battery 5 - - Davy’s Discoveries 5 - - Researches of Oersted, Ampère, Schweigger and Sturgeon 6 - - Ohm’s Law 7 - - Invention of the Dynamo 7 - - Daniell’s Battery 10 - - Grove’s Battery 11 - - Grove’s Demonstration of Incandescent Lighting 12 - - Grenet Battery 13 - - De Moleyns’ Incandescent Lamp 13 - - Early Developments of the Arc Lamp 14 - - Joule’s Law 16 - - Starr’s Incandescent Lamp 17 - - Other Early Incandescent Lamps 19 - - Further Arc Lamp Developments 20 - - Development of the Dynamo, 1840–1860 24 - - The First Commercial Installation of an Electric Light 25 - - Further Dynamo Developments 27 - - Russian Incandescent Lamp Inventors 30 - - The Jablochkoff “Candle” 31 - - Commercial Introduction of the Differentially Controlled Arc Lamp 33 - - Arc Lighting in the United States 33 - - Other American Arc Light Systems 40 - - “Sub-Dividing the Electric Light” 42 - - Edison’s Invention of a Practical Incandescent Lamp 43 - - Edison’s Three-Wire System 53 - - Development of the Alternating Current Constant Potential System 54 - - Incandescent Lamp Developments, 1884–1894 56 - - The Edison “Municipal” Street Lighting System 62 - - The Shunt Box System for Series Incandescent Lamps 64 - - The Enclosed Arc Lamp 65 - - The Flame Arc Lamp 67 - - The Constant Current Transformer for Series Circuits 69 - - Enclosed Series Alternating Current Arc Lamps 69 - - Series Incandescent Lamps on Constant Current Transformers 70 - - The Nernst Lamp 71 - - The Cooper-Hewitt Lamp 72 - - The Luminous or Magnetite Arc Lamp 74 - - Mercury Arc Rectifier for Magnetite Arc Lamps 77 - - Incandescent Lamp Developments, 1894–1904 78 - - The Moore Tube Light 79 - - The Osmium Lamp 82 - - The Gem Lamp 82 - - The Tantalum Lamp 84 - - Invention of the Tungsten Lamp 85 - - Drawn Tungsten Wire 87 - - The Quartz Mercury Vapor Arc Lamp 88 - - The Gas-Filled Tungsten Lamp 89 - - Types and Sizes of Tungsten Lamps Now Made 91 - - Standard Voltages 93 - - Cost of Incandescent Electric Light 93 - - Statistics Regarding the Present Demand for Lamps 94 - - Selected Bibliography 95 - - - - -LIST OF ILLUSTRATIONS - - - PAGE - - Portion of the Electrical Exhibit in the United States National - Museum viii - - Otto Von Guericke’s Electric Machine, 1650 2 - - Voltaic Pile, 1799 4 - - Faraday’s Dynamo, 1831 8 - - Pixii’s Dynamo, 1832 9 - - Daniell’s Cell, 1836 10 - - Grove’s Cell, 1838 11 - - Grove’s Incandescent Lamp, 1840 13 - - De Moleyns’ Incandescent Lamp, 1841 14 - - Wright’s Arc Lamp, 1845 15 - - Archereau’s Arc Lamp, 1848 16 - - Starr’s Incandescent Lamp, 1845 18 - - Staite’s Incandescent Lamp, 1848 19 - - Roberts’ Incandescent Lamp, 1852 19 - - Farmer’s Incandescent Lamp, 1859 20 - - Roberts’ Arc Lamp, 1852 21 - - Slater and Watson’s Arc Lamp, 1852 21 - - Diagram of “Differential” Method of Control of an Arc Lamp 22 - - Lacassagne and Thiers’ Differentially Controlled Arc Lamp, 1856 23 - - Serrin’s Arc Lamp, 1857 24 - - Siemens’ Dynamo, 1856 25 - - Alliance Dynamo, 1862 26 - - Wheatstone’s Self-Excited Dynamo, 1866 27 - - Gramme’s Dynamo, 1871 28 - - Gramme’s “Ring” Armature 28 - - Alteneck’s Dynamo with “Drum” Wound Armature, 1872 29 - - Lodyguine’s Incandescent Lamp, 1872 30 - - Konn’s Incandescent Lamp, 1875 30 - - Bouliguine’s Incandescent Lamp, 1876 31 - - Jablochkoff “Candle,” 1876 32 - - Jablochkoff’s Alternating Current Dynamo, 1876 33 - - Wallace-Farmer Arc Lamp, 1875 34 - - Wallace-Farmer Dynamo, 1875 34 - - Weston’s Arc Lamp, 1876 35 - - Brush’s Dynamo, 1877 36 - - Diagram of Brush Armature 36 - - Brush’s Arc Lamp, 1877 37 - - Thomson-Houston Arc Dynamo, 1878 38 - - Diagram of T-H Arc Lighting System 39 - - Thomson-Houston Arc Lamp, 1878 40 - - Thomson Double Carbon Arc Lamp 40 - - Maxim Dynamo 41 - - Sawyer’s Incandescent Lamp, 1878 42 - - Farmer’s Incandescent Lamp, 1878 42 - - Maxim’s Incandescent Lamp, 1878 43 - - Edison’s First Experimental Lamp, 1878 44 - - Diagram of Constant Current Series System 45 - - Diagram of Edison’s Multiple System, 1879 45 - - Edison Dynamo, 1879 46 - - Edison’s High Resistance Platinum Lamp, 1879 47 - - Edison’s High Resistance Platinum in Vacuum Lamp, 1879 47 - - Edison’s Carbon Lamp of October 21, 1879 48 - - Demonstration of Edison’s Incandescent Lighting System 49 - - Dynamo Room, S. S. Columbia 50 - - Original Socket for Incandescent Lamps 51 - - Wire Terminal Base Lamp, 1880 51 - - Original Screw Base Lamp, 1880 52 - - Improved Screw Base Lamp, 1881 52 - - Final Form of Screw Base, 1881 53 - - Diagram of Edison’s Three Wire System, 1881 54 - - Diagram of Stanley’s Alternating Current Multiple System, 1885 55 - - Standard Edison Lamp, 1884 56 - - Standard Edison Lamp, 1888 56 - - Standard Edison Lamp, 1894 57 - - Various Bases in Use, 1892 58 - - Thomson-Houston Socket 59 - - Westinghouse Socket 59 - - Adapters for Edison Screw Sockets, 1892 60 - - Various Series Bases in Use, 1892 61 - - Edison “Municipal” System, 1885 62 - - Edison “Municipal” Lamp, 1885 63 - - Shunt Box System, 1887 64 - - Enclosed Arc Lamp, 1893 65 - - Open Flame Arc Lamp, 1898 66 - - Enclosed Flame Arc Lamp, 1908 66 - - Constant Current Transformer, 1900 68 - - Series Incandescent Lamp Socket with Film Cutout, 1900 70 - - Nernst Lamp, 1900 71 - - Diagram of Nernst Lamp 72 - - Cooper-Hewitt Mercury Vapor Arc Lamp, 1901 73 - - Diagram of Cooper-Hewitt Lamp for Use on Alternating Current 74 - - Luminous or Magnetite Arc Lamp, 1902 75 - - Diagram of Series Magnetite Arc Lamp 76 - - Mercury Arc Rectifier Tube for Series Magnetite Arc Circuits, 1902 77 - - Early Mercury Arc Rectifier Installation 78 - - The Moore Tube Light, 1904 79 - - Diagram of Feeder Valve of Moore Tube 80 - - Osmium Lamp, 1905 82 - - Gem Lamp, 1905 83 - - Tantalum Lamp, 1906 84 - - Tungsten Lamp, 1907 86 - - Drawn Tungsten Wire Lamp, 1911 87 - - Quartz Mercury Vapor Lamp, 1912 88 - - Gas Filled Tungsten Lamp, 1913 89 - - Gas Filled Tungsten Lamp, 1923 90 - - Standard Tungsten Lamps, 1923 92 - - -[Illustration: PORTION OF THE ELECTRICAL EXHIBIT IN THE UNITED STATES -NATIONAL MUSEUM. - -Section devoted to the historical development of the electric light and -dynamo.] - - - - -FOREWORD - - -In the year 1884 a Section of Transportation was organized in the -United States National Museum for the purpose of preparing and -assembling educational exhibits of a few objects of railroad machinery -which had been obtained both from the Centennial Exhibition held in -Philadelphia in 1876 and still earlier as incidentals to ethnological -collections, and to secure other collections relating to the railway -industry. - -From this beginning the section was expanded to include the whole -field of engineering and is designated at present as the Divisions of -Mineral and Mechanical Technology. The growth and enlargement of the -collections has been particularly marked in the fields of mining and -mineral industries; mechanical engineering, especially pertaining to -the steam engine, internal combustion engine and locomotive; naval -architecture, and electrical engineering, particularly the development -of the telegraph, telephone and the electric light. - -In the acquisition of objects visualizing the history of electric -light the Museum has been rather fortunate, particularly as regards -the developments in the United States. Thus mention may be made of -the original Patent Office models of the more important dynamos, arc -lights and incandescent lights, together with original commercial -apparatus after these models; a unit of the equipment used in the -first commercially successful installation on land of an incandescent -lighting system, presented by Joseph E. Hinds in whose engraving -establishment in New York City the installation was made in 1881; and -a large series of incandescent lights, mainly originals, visualizing -chronologically the developments of the Edison light from its -inception, presented at intervals since the year 1898 by the General -Electric Company. - -The object of all collections in the Divisions is to visualize -broadly the steps by which advances have been made in each field of -engineering; to show the layman the fundamental and general principles -which are the basis for the developments; and to familiarize the -engineer with branches of engineering other than his own. Normally -when a subject is completely covered by a collection of objects, a -paper is prepared and published describing the collection and the -story it portrays. In the present instance, however, on account of -the uncertainty of the time of completing the collection, if it is -possible ever to bring this about, it was thought advisable to publish -Mr. Schroeder’s paper which draws upon the Museum collection as -completely as possible. - - CARL W. MITMAN, - ~Curator, Divisions of Mineral and - Mechanical Technology, - U. S. National Museum~. - - - - -CHRONOLOGY OF ELECTRIC LIGHT - - - 1800--Allesandro Volta demonstrated his discovery that electricity - can be generated by chemical means. The VOLT, the unit of - electric pressure, is named in his honor for this discovery - of the electric battery. - - 1802--Sir Humphry Davy demonstrated that electric current can heat - carbon and strips of metal to incandescence and give light. - - 1809--Sir Humphry Davy demonstrated that current will give a - brilliant flame between the ends of two carbon pencils - which are first allowed to touch each other and then pulled - apart. This light he called the “arc” on account of its - arch shape. - - 1820--André Marie Ampère discovered that current flowing through - a coiled wire gives it the properties of a magnet. The - AMPERE, the unit of flow of electric current, is named in - his honor for this discovery. - - 1825--Georg Simon Ohm discovered the relation between the voltage, - ampereage and resistance in an electric circuit, which is - called Ohm’s Law. The OHM, the unit of electric resistance, - is named in his honor for this discovery. - - 1831--Michael Faraday discovered that electricity can be generated - by moving a wire in the neighborhood of a magnet, the - principle of the dynamo. - - 1840--Sir William Robert Grove demonstrated his experimental - incandescent lamp in which platinum is made incandescent by - current flowing through it. - - 1841--Frederick De Moleyns obtained the first patent on an - incandescent lamp. The burner was powdered charcoal - operating in an exhausted glass globe. - - 1845--Thomas Wright obtained the first patent on an arc light. - - 1845--J. W. Starr invented an incandescent lamp consisting of a - carbon pencil operating in the vacuum above a column of - mercury. - - 1856--Joseph Lacassagne and Henry Thiers invented the - “differential” method of control of the arc which was - universally used twenty years later when the arc lamp was - commercially established. - - 1862--The first commercial installation of an electric light. An - arc light was put in a lighthouse in England. - - 1866--Sir Charles Wheatstone invented the “self-excited” dynamo, - now universally used. - - 1872--Lodyguine invented an incandescent lamp having a graphite - burner operating in nitrogen gas. - - 1876--Paul Jablochkoff invented the “electric candle,” an arc light - commercially used for lighting the boulevards in Paris. - - 1877–8--Arc light systems commercially established in the United - States by William Wallace and Prof. Moses Farmer, Edward - Weston, Charles F. Brush and Prof. Elihu Thomson and Edwin - J. Houston. - - 1879--Thomas Alva Edison invented an incandescent lamp consisting - of a high resistance carbon filament operating in a - high vacuum maintained by an all glass globe. These - principles are used in all incandescent lamps made today. - He also invented a completely new system of distributing - electricity at constant pressure, now universally used. - - 1882--Lucien Goulard and John D. Gibbs invented a series - alternating current system of distributing electric - current. This has not been commercially used. - - 1886--William Stanley invented a constant pressure alternating - current system of distribution. This is universally used - where current is to be distributed long distances. - - 1893--Louis B. Marks invented the enclosed carbon arc lamp. - - 1898--Bremer’s invention of the flame arc lamp, having carbons - impregnated with various salts, commercially established. - - 1900--Dr. Walther Nernst’s invention of the Nernst lamp - commercially established. The burner consisted of various - oxides, such as zirconia, which operated in the open air. - - 1901--Dr. Peter Cooper Hewitt’s invention of the mercury arc light - commercially established. - - 1902--The magnetite arc lamp was developed by C. A. B. Halvorson, - Jr. This has a new method of control of the arc. The - negative electrode consists of a mixture of magnetite and - other substances packed in an iron tube. - - 1904--D. McFarlan Moore’s invention of the Moore vacuum tube light - commercially established. This consisted of a long tube, - made in lengths up to 200 feet, from which the air had been - exhausted to about a thousandth of an atmosphere. High - voltage current passing through this rarefied atmosphere - caused it to glow. Rarefied carbon dioxide gas was later - used. - - 1905--Dr. Auer von Welsbach’s invention of the osmium incandescent - lamp commercially established, but only on a small scale - in Europe. The metal osmium, used for the filament which - operated in vacuum, is rarer and more expensive than - platinum. - - 1905--Dr. Willis R. Whitney’s invention of the Gem incandescent - lamp commercially established. The carbon filament had been - heated to a very high temperature in an electric resistance - furnace invented by him. The lamp was 25 per cent more - efficient than the regular carbon lamp. - - 1906--Dr. Werner von Bolton’s invention of the tantalum - incandescent lamp commercially established. - - 1907--Alexander Just and Franz Hanaman’s invention of the tungsten - filament incandescent lamp commercially established. - - 1911--Dr. William D. Coolidge’s invention of drawn tungsten wire - commercially established. - - 1913--Dr. Irving Langmuir’s invention of the gas-filled tungsten - filament incandescent lamp commercially established. - - - - - HISTORY OF ELECTRIC LIGHT - - BY HENRY SCHROEDER, - HARRISON, NEW JERSEY. - - - - -EARLY RECORDS OF ELECTRICITY AND MAGNETISM - - -About twenty-five centuries ago, Thales, a Greek philosopher, recorded -the fact that if amber is rubbed it will attract light objects. -The Greeks called amber “elektron,” from which we get the word -“electricity.” About two hundred and fifty years later, Aristotle, -another Greek philosopher, mentioned that the lodestone would attract -iron. Lodestone is an iron ore (Fe_{3}O_{4}), having magnetic qualities -and is now called magnetite. The word “magnet” comes from the fact that -the best specimens of lodestones came from Magnesia, a city in Asia -Minor. Plutarch, a Greek biographer, wrote about 100 A. D., that iron -is sometimes attracted and at other times repelled by a lodestone. This -indicates that the piece of iron was magnetised by the lodestone. - -In 1180, Alexander Neckham, an English Monk, described the compass, -which probably had been invented by sailors of the northern countries -of Europe, although its invention has been credited to the Chinese. -Early compasses probably consisted of an iron needle, magnetised by -a lodestone, mounted on a piece of wood floating in water. The word -lodestone or “leading stone” comes from the fact that it would point -towards the north if suspended like a compass. - -William Gilbert, physician to Queen Elizabeth of England, wrote a -book about the year 1600 giving all the information then known on -the subject. He also described his experiments, showing, among other -things, the existence of magnetic lines of force and of north and south -poles in a magnet. Robert Norman had discovered a few years previously -that a compass needle mounted on a horizontal axis would dip downward. -Gilbert cut a large lodestone into a sphere, and observed that the -needle did not dip at the equator of this sphere, the dip increasing -to 90 degrees as the poles were approached. From this he deduced that -the earth was a magnet with the magnetic north pole at the geographic -north pole. It has since been determined that these two poles do not -coincide. Gilbert suggested the use of the dipping needle to determine -latitude. He also discovered that other substances, beside amber, would -attract light objects if rubbed. - - - - -MACHINES GENERATING ELECTRICITY BY FRICTION - - -Otto Von Guericke was mayor of the city of Magdeburg as well as a -philosopher. About 1650 he made a machine consisting of a ball of -sulphur mounted on a shaft which could be rotated. Electricity was -generated when the hand was pressed against the globe as it rotated. -He also discovered that electricity could be conducted away from the -globe by a chain and would appear at the other end of the chain. Von -Guericke also invented the vacuum air pump. In 1709, Francis Hawksbee, -an Englishman, made a similar machine, using a hollow glass globe which -could be exhausted. The exhausted globe when rotated at high speed and -rubbed by hand would produce a glowing light. This “electric light” as -it was called, created great excitement when it was shown before the -Royal Society, a gathering of scientists, in London. - -[Illustration: OTTO VON GUERICKE’S ELECTRIC MACHINE, 1650. - -A ball of sulphur was rotated, electricity being generated when it -rubbed against the hand.] - -Stephen Gray, twenty years later, showed the Royal Society that -electricity could be conducted about a thousand feet by a hemp thread, -supported by silk threads. If metal supports were used, this could not -be done. Charles du Fay, a Frenchman, repeated Gray’s experiments, -and showed in 1733 that the substances which were insulators, and -which Gilbert had discovered, would become electrified if rubbed. -Those substances which Gilbert could not electrify were conductors of -electricity. - - - - -THE LEYDEN JAR - - -The thought came to Von Kleist, Bishop of Pomerania, Germany, about -1745, that electricity could be stored. The frictional machines -generated so small an amount of electricity (though, as is now known, -at a very high pressure--several thousand volts) that he thought he -could increase the quantity by storing it. Knowing that glass was -an insulator and water a conductor, he filled a glass bottle partly -full of water with a nail in the cork to connect the machine with the -water. Holding the bottle in one hand and turning the machine with -the other for a few minutes, he then disconnected the bottle from the -machine. When he touched the nail with his other hand he received a -shock which nearly stunned him. This was called the Leyden jar, the -forerunner of the present condenser. It received its name from the fact -that its discovery was also made a short time after by experimenters -in the University of Leyden. Further experiments showed that the hand -holding the bottle was as essential as the water inside, so these were -substituted by tin foil coatings inside and outside the bottle. - -Benjamin Franklin, American statesman, scientist and printer, made -numerous experiments with the Leyden jar. He connected several jars -in parallel, as he called it, which gave a discharge strong enough to -kill a turkey. He also connected the jars in series, or “in cascade” as -he called it, thus establishing the principle of parallel and series -connections. Noticing the similarity between the electric spark and -lightning, Franklin in 1752, performed his famous kite experiment. -Flying a kite in a thunderstorm, he drew electricity from the clouds to -charge Leyden jars, which were later discharged, proving that lightning -and electricity were the same. This led him to invent the lightning rod. - - - - -ELECTRICITY GENERATED BY CHEMICAL MEANS - - -Luigi Galvani was an Italian scientist. About 1785, so the story goes, -his wife was in delicate health, and some frog legs were being skinned -to make her a nourishing soup. An assistant holding the legs with a -metal clamp and cutting the skin with a scalpel, happened to let the -clamp and scalpel touch each other. To his amazement the frog legs -twitched. Galvani repeated the experiment many times by touching -the nerve with a metal rod and the muscle with a different metal rod -and allowing the rods to touch, and propounded the theory of animal -electricity in a paper he published in 1791. - -Allesandro Volta, a professor of physics in the University of Pavia, -Italy, read about Galvani’s work and repeated his experiments. He -found that the extent of the movement of the frog legs depended on the -metals used for the rods, and thus believed that the electric charge -was produced by the contact of dissimilar metals with the moisture in -the muscles. To prove his point he made a pile of silver and zinc discs -with cloths, wet with salt water, between them. This was in 1799, and -he described his pile in March, 1800, in a letter to the Royal Society -in London. - -[Illustration: VOLTAIC PILE, 1799. - -Volta discovered that electricity could be generated by chemical means -and made a pile of silver and zinc discs with cloths, wet with salt -water, between them. This was the forerunner of the present-day dry -battery. Photograph courtesy Prof. Chas. F. Chandler Museum, Columbia -University, New York.] - -This was an epoch-making discovery as it was the forerunner of the -present-day primary battery. Volta soon found that the generation of -electricity became weaker as the cloths became dry, so to overcome -this he made his “crown of cups.” This consisted of a series of cups -containing salt water in which strips of silver and zinc were dipped. -Each strip of silver in one cup was connected to the zinc strip in -the next cup, the end strips of silver and zinc being terminals of -the battery. This was the first time that a continuous supply of -electricity in reasonable quantities was made available, so the VOLT, -the unit of electrical pressure was named in his honor. It was later -shown that the chemical affinity of one of the metals in the liquid was -converted into electric energy. The chemical action of Volta’s battery -is that the salt water attacks the zinc when the circuit is closed -forming zinc chloride, caustic soda and hydrogen gas. The chemical -equation is: - - Zn + 2NaCl + 2H_{2}O = ZnCl_{2} + 2NaOH + H_{2} - - - - -IMPROVEMENT OF VOLTA’S BATTERY - - -It was early suggested that sheets of silver and zinc be soldered -together back to back and that a trough be divided into cells by these -bimetal sheets being put into grooves cut in the sides and bottom of -the trough. This is the reason why one unit of a battery is called a -“cell.” It was soon found that a more powerful cell could be made if -copper, zinc and dilute sulphuric acid were used. The zinc is dissolved -by the acid forming zinc sulphate and hydrogen gas, thus: - - Zn + H_{2}SO_{4} = ZnSO_{4} + H_{2} - -The hydrogen gas appears as bubbles on the copper and reduces the open -circuit voltage (about 0.8 volt per cell) as current is taken from the -battery. This is called “polarization.” Owing to minute impurities in -the zinc, it is attacked by the acid even when no current is taken from -the battery, the impurities forming with the zinc a short circuited -local cell. This is called “local action,” and this difficulty was at -first overcome by removing the zinc from the acid when the battery was -not in use. - - - - -DAVY’S DISCOVERIES - - -Sir Humphry Davy was a well-known English chemist, and with the aid of -powerful batteries constructed for the Royal Institution in London, -he made numerous experiments on the chemical effects of electricity. -He decomposed a number of substances and discovered the elements -boron, potassium and sodium. He heated strips of various metals to -incandescence by passing current through them, and showed that platinum -would stay incandescent for some time without oxidizing. This was about -1802. - -In the early frictional machines, the presence of electricity was shown -by the fact that sparks could be obtained. Similarly the breaking -of the circuit of a battery would give a spark. Davy, about 1809, -demonstrated that this spark could be maintained for a long time with -the large battery of 2000 cells he had had constructed. Using two -sticks of charcoal connected by wires to the terminals of this very -powerful battery, he demonstrated before the Royal Society the light -produced by touching the sticks together and then holding them apart -horizontally about three inches. The brilliant flame obtained he called -an “arc” because of its arch shape, the heated gases, rising, assuming -this form. Davy was given the degree of LL. D. for his distinguished -research work, and was knighted on the eve of his marriage, April 11, -1812. - - - - -RESEARCHES OF OERSTED, AMPÈRE, SCHWEIGGER AND STURGEON - - -Hans Christian Oersted was a professor of physics at the University of -Copenhagen in Denmark. One day in 1819, while addressing his students, -he happened to hold a wire, through which current was flowing, over -a large compass. To his surprise he saw the compass was deflected -from its true position. He promptly made a number of experiments and -discovered that by reversing the current the compass was deflected in -the opposite direction. Oersted announced his discovery in 1820. - -André Marie Ampère was a professor of mathematics in the Ecole -Polytechnic in Paris. Hearing of Oersted’s discovery, he immediately -made some experiments and made the further discovery in 1820 that if -the wire is coiled and current passed through it, the coil had all the -properties of a magnet. - -These two discoveries led to the invention of Schweigger in 1820, -of the galvanometer (or “multiplier” as it was then called), a very -sensitive instrument for measuring electric currents. It consisted of -a delicate compass needle suspended in a coil of many turns of wire. -Current in the coil deflected the needle, the direction and amount of -deflection indicating the direction and strength of the current. Ampère -further made the discovery that currents in opposite directions repel -and in the same directions attract each other. He also gave a rule -for determining the direction of the current by the deflection of the -compass needle. He developed the theory that magnetism is caused by -electricity flowing around the circumference of the body magnetised. -The AMPERE, the unit of flow of electric current, was named in honor of -his discoveries. - -In 1825 it was shown by Sturgeon that if a bar of iron were placed in -the coil, its magnetic strength would be very greatly increased, which -he called an electro-magnet. - - - - -OHM’S LAW - - -Georg Simon Ohm was born in Bavaria, the oldest son of a poor -blacksmith. With the aid of friends he went to college and became a -teacher. It had been shown that the rate of transfer of heat from one -end to the other of a metal bar is proportional to the difference -of temperature between the ends. About 1825, Ohm, by analogy and -experiment, found that the current in a conductor is proportional to -the difference of electric pressure (voltage) between its ends. He -further showed that with a given difference of voltage, the current -in different conductors is inversely proportional to the resistance -of the conductor. Ohm therefore propounded the law that the current -flowing in a circuit is equal to the voltage on that circuit divided by -the resistance of the circuit. In honor of this discovery, the unit of -electrical resistance is called the OHM. This law is usually expressed -as: - - C = E/R - -“C” meaning current (in amperes), “E” meaning electromotive force or -voltage (in volts) and “R” meaning resistance (in ohms). - -This is one of the fundamental laws of electricity and if thoroughly -understood, will solve many electrical problems. Thus, if any two of -the above units are known, the third can be determined. Examples: An -incandescent lamp on a 120-volt circuit consumes 0.4 ampere, hence its -resistance under such conditions is 300 ohms. Several trolley cars at -the end of a line take 100 amperes to run them and the resistance of -the overhead wire from the power house to the trolley cars is half -an ohm; the drop in voltage on the line between the power house and -trolley cars is therefore 50 volts, so that if the voltage at the power -house were 600, it would be 550 volts at the end of the line. - -Critics derided Ohm’s law so that he was forced out of his position -as teacher in the High School in Cologne. Finally after ten years Ohm -began to find supporters and in 1841 his law was publicly recognized by -the Royal Society of London which presented him with the Copley medal. - - - - -INVENTION OF THE DYNAMO - - -Michael Faraday was an English scientist. Born of parents in poor -circumstances, he became a bookbinder and studied books on electricity -and chemistry. He finally obtained a position as laboratory assistant -to Sir Humphry Davy helping him with his lectures and experiments. He -also made a number of experiments himself and succeeded in liquifying -chlorine gas for which he was elected to a Fellowship in the Royal -Institution in 1824. Following up Oersted’s and Ampère’s work, he -endeavored to find the relation between electricity and magnetism. -Finally on Oct. 17, 1831, he made the experiment of moving a permanent -bar magnet in and out of a coil of wire connected to a galvanometer. -This generated electricity in the coil which deflected the galvanometer -needle. A few days after, Oct. 28, 1831, he mounted a copper disk -on a shaft so that the disk could be rotated between the poles of -a permanent horseshoe magnet. The shaft and edge of the disk were -connected by brushes and wires to a galvanometer, the needle of which -was deflected as the disk was rotated. A paper on his invention was -read before the Royal Society on November 24, 1831, which appeared in -printed form in January, 1832. - -[Illustration: FARADAY’S DYNAMO, 1831. - -Faraday discovered that electricity could be generated by means of a -permanent magnet. This principle is used in all dynamos.] - -Faraday did not develop his invention any further, being satisfied, -as in all his work, in pure research. His was a notable invention but -it remained for others to make it practicable. Hippolyte Pixii, a -Frenchman, made a dynamo in 1832 consisting of a permanent horseshoe -magnet which could be rotated between two wire bobbins mounted on a -soft iron core. The wires from the bobbins were connected to a pair of -brushes touching a commutator mounted on the shaft holding the magnet, -and other brushes carried the current from the commutator so that the -alternating current generated was rectified into direct current. - -[Illustration: PIXII’S DYNAMO, 1832. - -Pixii made an improvement by rotating a permanent magnet in the -neighborhood of coils of wire mounted on a soft iron core. A commutator -rectified the alternating current generated into direct current. This -dynamo is in the collection of the Smithsonian Institution.] - -E. M. Clarke, an Englishman made, in 1834, another dynamo in which the -bobbins rotated alongside of the poles of a permanent horseshoe magnet. -He also made a commutator so that the machine produced direct current. -None of these machines gave more than feeble current at low pressure. -The large primary batteries that had been made were much more powerful, -although expensive to operate. It has been estimated that the cost of -current from the 2000-cell battery to operate the demonstration of the -arc light by Davy, was six dollars a minute. At present retail rates -for electricity sold by lighting companies, six dollars would operate -Davy’s arc light about 500 hours or 30,000 times as long. - - - - -DANIELL’S BATTERY - - -[Illustration: DANIELL’S CELL, 1836. - -Daniell invented a battery consisting of zinc, copper and copper -sulphate. Later the porous cup was dispensed with, which was used to -keep the sulphuric acid formed separate from the solution of copper -sulphate, the two liquids then being kept apart by their difference in -specific gravity. It was then called the Gravity Battery and for years -was used in telegraphy.] - -It was soon discovered that if the zinc electrode were rubbed with -mercury (amalgamated), the local action would practically cease, and if -the hydrogen bubbles were removed, the operating voltage of the cell -would be increased. John Frederic Daniell, an English chemist, invented -a cell in 1836 to overcome these difficulties. His cell consisted -of a glass jar containing a saturated solution of copper sulphate -(CuSO_{4}). A copper cylinder, open at both ends and perforated with -holes, was put into this solution. On the outside of the copper -cylinder there was a copper ring, located below the surface of the -solution, acting as a shelf to support crystals of copper sulphate. -Inside the cylinder there was a porous earthenware jar containing -dilute sulphuric acid and an amalgamated zinc rod. The two liquids were -therefore kept apart but in contact with each other through the pores -of the jar. The hydrogen gas given off by the action of the sulphuric -acid on the zinc, combined with the dissolved copper sulphate, formed -sulphuric acid and metallic copper. The latter was deposited on the -copper cylinder which acted as the other electrode. Thus the copper -sulphate acted as a depolarizer. - -The chemical reactions in this cell are, - - In inner porous jar: Zn + H_{2}SO_{4} = ZnSO_{4} + H_{2} - In outer glass jar: H_{2} + CuSO_{4} = H_{2}SO_{4} + Cu - -This cell had an open circuit voltage of a little over one volt. Later -the porous cup was dispensed with, the two liquids being kept apart -by the difference of their specific gravities. This was known as the -Gravity cell, and for years was used in telegraphy. - -[Illustration: GROVE’S CELL, 1838. - -This consisted of zinc, sulphuric acid, nitric acid and platinum. It -made a very powerful battery. The nitric acid is called the depolarizer -as it absorbs the hydrogen gas formed, thus improving the operating -voltage.] - - - - -GROVE’S BATTERY - - -Sir William Robert Grove, an English Judge and scientist, invented a -cell in 1838 consisting of a platinum electrode in strong nitric acid -in a porous earthenware jar. This jar was put in dilute sulphuric acid -in a glass jar in which there was an amalgamated zinc plate for the -other electrode. This had an open circuit voltage of about 1.9 volts. -The porous jar was used to prevent the nitric acid from attacking the -zinc. The nitric acid was used for the purpose of combining with the -hydrogen gas set free by the action of the sulphuric acid on the zinc, -and hence was the depolarizing agent. Hydrogen combining with nitric -acid forms nitrous peroxide and water. Part of the nitrous peroxide is -dissolved in the water, and the rest escapes as fumes which, however, -are very suffocating. - -The chemical equations of this cell are as follows: - - In outer glass jar: Zn + H_{2}SO_{4} = ZnSO_{4} + H_{2} - In inner porous jar: H_{2} + 2HNO_{3} = N_{2}O_{4} + 2H_{2}O - -An interesting thing about Grove’s cell is that it was planned in -accordance with a theory. Grove knew that the electrical energy of -the zinc-sulphuric acid cell came from the chemical affinity of the -two reagents, and if the hydrogen gas set free could be combined with -oxygen (to form water--H_{2}O), such chemical affinity should increase -the strength of the cell. As the hydrogen gas appears at the other -electrode, the oxidizing agent should surround that electrode. Nitric -acid was known at that time as one of the most powerful oxidizing -liquids, but as it attacks copper, he used platinum for the other -electrode. Thus he not only overcame the difficulty of polarization by -the hydrogen gas, but also increased the voltage of the cell by the -added chemical action of the combination of hydrogen and oxygen. - - - - -GROVE’S DEMONSTRATION OF INCANDESCENT LIGHTING - - -In 1840 Grove made an experimental lamp by attaching the ends of a coil -of platinum wire to copper wires, the lower parts of which were well -varnished for insulation. The platinum wire was covered by a glass -tumbler, the open end set in a glass dish partly filled with water. -This prevented draughts of air from cooling the incandescent platinum, -and the small amount of oxygen of the air in the tumbler reduced the -amount of oxidization of the platinum that would otherwise occur. With -current supplied by a large number of cells of his battery, he lighted -the auditorium of the Royal Institution with these lamps during one -of the lectures he gave. This lamp gave only a feeble light as there -was danger of melting the platinum and platinum gives but little light -unless operated close to its melting temperature. It also required a -lot of current to operate it as the air tended to cool the incandescent -platinum. The demonstration was only of scientific interest, the cost -of current being much too great (estimated at several hundred dollars a -kilowatt hour) to make it commercial. - - - - -GRENET BATTERY - - -It was discovered that chromic anhydride gives up oxygen easier than -nitric acid and consequently if used would give a higher voltage than -Grove’s nitric acid battery. It also has the advantage of a lesser -tendency to attack zinc directly if it happens to come in contact with -it. Grenet developed a cell having a liquid consisting of a mixture of -potassium bichromate (K_{2}Cr_{2}O_{7}) and sulphuric acid. A porous -cell was therefore not used to keep the two liquids apart. This had the -advantage of reducing the internal resistance. The chemical reaction -was: - - K_{2}Cr_{2}O_{7} (potassium bichromate) + 7H_{2}SO_{4} (sulphuric - acid) + 3Zn (zinc) = 3ZnSO_{4} (zinc sulphate) + K_{2}SO_{4} - (potassium sulphate) + Cr_{2} (SO_{4})_{3} (chromium sulphate) - + 7H_{2}O (water). - -In order to prevent the useless consumption of zinc on open circuit, -the zinc was attached to a sliding rod and could be drawn up into the -neck of the bottle-shaped jar containing the liquid. - -[Illustration: GROVE’S INCANDESCENT LAMP, 1840. - -Grove made an experimental lamp, using platinum for the burner which -was protected from draughts of air by a glass tumbler.] - - - - -DE MOLEYNS’ INCANDESCENT LAMP - - -Frederick De Moleyns, an Englishman, has the honor of having obtained -the first patent on an incandescent lamp. This was in 1841 and his -lamp was quite novel. It consisted of a spherical glass globe, in the -upper part of which was a tube containing powdered charcoal. This tube -was open at the bottom inside the globe and through it ran a platinum -wire, the end below the tube being coiled. Another platinum wire coiled -at its upper end came up through the lower part of the globe but did -not quite touch the other platinum coil. The powdered charcoal filled -the two coils of platinum wire and bridged the gap between. Current -passing through this charcoal bridge heated it to incandescence. The -air in the globe having been removed as far as was possible with the -hand air pumps then available, the charcoal did not immediately burn -up, the small amount consumed being replaced by the supply in the -tube. The idea was ingenious but the lamp was impractical as the globe -rapidly blackened from the evaporation of the incandescent charcoal. - -[Illustration: DE MOLEYNS’ INCANDESCENT LAMP, 1841. - -This consisted of two coils of platinum wire containing powdered -charcoal operating in a vacuum. It is only of interest as the first -incandescent lamp on which a patent (British) was granted.] - - - - -EARLY DEVELOPMENTS OF THE ARC LAMP - - -It had been found that most of the light of the arc came from the -tip of the positive electrode, and that the charcoal electrodes were -rapidly consumed, the positive electrode about twice as fast as the -negative. Mechanisms were designed to take care of this, together with -devices to start the arc by allowing the electrodes to touch each other -and then pulling them apart the proper distance. This distance varied -from one-eighth to three-quarters of an inch. - -In 1840 Bunsen, the German chemist who invented the bunsen burner, -devised a process for making hard dense carbon pencils which lasted -much longer than the charcoal previously used. The dense carbon from -the inside of the retorts of gas making plants was ground up and mixed -with molasses, moulded into shape and baked at a high temperature. -Bunsen also, in 1843, cheapened Grove’s battery by substituting a hard -carbon plate in place of the platinum electrode. - -[Illustration: WRIGHT’S ARC LAMP, 1845. - -This lamp is also only of interest as the first arc lamp on which a -patent (British) was granted. Four arcs played between the five carbon -discs.] - -Thomas Wright, an Englishman, was the first to patent an arc lamp. -This was in 1845, and the lamp was a hand regulated device consisting -of five carbon disks normally touching each other and rotated by -clockwork. Two of the disks could be drawn outward by thumb screws, -which was to be done after the current was turned on thus establishing -four arcs, one between each pair of disks. The next year, 1846, W. E. -Staite, another Englishman, made an arc lamp having two vertical carbon -pencils. The upper was stationary. The lower was movable and actuated -by clockwork directed by ratchets which in turn were regulated by an -electro-magnet controlled by the current flowing through the arc. Thus -the lower carbon would be moved up or down as required. - -Archereau, a Frenchman, made a very simple arc lamp in 1848. The upper -carbon was fixed and the lower one was mounted on a piece of iron -which could be drawn down into a coil of wire. The weight of the lower -electrode was overbalanced by a counterweight, so that when no current -was flowing the two carbons would touch. When current was turned on, it -flowed through the two carbons and through the coil of wire (solenoid) -which then became energized and pulled the lower carbon down, thus -striking the arc. Two of these arc lamps were installed in Paris -and caused considerable excitement. After a few weeks of unreliable -operation, it was found that the cost of current from the batteries was -much too great to continue their use commercially. The dynamo had not -progressed far enough to permit its use. - -[Illustration: ARCHEREAU’S ARC LAMP, 1848. - -This simple arc was controlled by an electro-magnet, and two lamps were -installed for street lighting in Paris, current being obtained from -batteries.] - - - - -JOULE’S LAW - - -Joule was an Englishman, and in 1842 began investigating the relation -between mechanical energy and heat. He first showed that, by allowing -a weight to drop from a considerable height and turn a paddle wheel in -water, the temperature of the water would increase in relation to the -work done in turning the wheel. It is now known that 778 foot-pounds -(1 lb. falling 778 feet, 10 lbs. falling 77.8 feet or 778 lbs. falling -one foot, etc.) is the mechanical equivalent of energy equal to raising -one pound of water one degree Fahrenheit. The rate of energy (power) -is the energy divided by a unit of time; thus one horsepower is 33,000 -foot-pounds per minute. Joule next investigated the relation between -heat and electric current. He made a device consisting of a vessel of -water in which there were a thermometer and an insulated coil of wire -having a considerable resistance. He found that an electric current -heated the water, and making many combinations of the amount and length -of time of current flowing and of the resistance of the wire, he -deduced the law that the energy in an electric circuit is proportional -to the square of the amount of current flowing multiplied by the length -of time and multiplied by the resistance of the wire. - -The rate of electrical energy (electric power) is therefore -proportional to the square of current multiplied by the resistance. -The electrical unit of power is now called the WATT, named in honor of -James Watt, the Englishman, who made great improvements to the steam -engine about a century ago. Thus, watts = C^{2}R and substituting the -value of R from Ohm’s law, C = E/R, we get - - Watts = Volts × Amperes - -The watt is a small unit of electric power, as can be seen from the -fact that 746 watts are equal to one horsepower. The kilowatt, kilo -being the Greek word for thousand, is 1000 watts. - -This term is an important one in the electrical industry. For example, -dynamos are rated in kilowatts, expressed as KW; the largest one -made so far is 50,000 KW which is 66,666 horsepower. Edison’s first -commercial dynamo had a capacity of 6 KW although the terms watts -and kilowatts were not in use at that time. The ordinary sizes of -incandescent lamps now used in the home are 25, 40 and 50 watts. - - - - -STARR’S INCANDESCENT LAMP - - -[Illustration: STARR’S INCANDESCENT LAMP, 1845. - -This consisted of a short carbon pencil operating in the vacuum above a -column of mercury.] - -J. W. Starr, an American, of Cincinnati, Ohio, assisted financially by -Peabody, the philanthropist, went to England where he obtained a patent -in 1845 on the lamps he had invented, although the patent was taken -out under the name of King, his attorney. One is of passing interest -only. It consisted of a strip of platinum, the active length of which -could be adjusted to fit the battery strength used, and was covered -by a glass globe to protect it from draughts of air. The other, a -carbon lamp, was the first real contribution to the art. It consisted -of a rod of carbon operating in the vacuum above a column of mercury -(Torrecellium vacuum) as in a barometer. A heavy platinum wire was -sealed in the upper closed end of a large glass tube, and connected -to the carbon rod by an iron clamp. The lower end of the carbon rod -was fastened to another iron clamp, the two clamps being held in place -and insulated from each other by a porcelain rod. Attached to the -lower clamp was a long copper wire. Just below the lower clamp, the -glass tube was narrowed down and had a length of more than 30 inches. -The tube was then filled with mercury, the bottom of the tube being -put into a vessel partly full of mercury. The mercury ran out of the -enlarged upper part of the tube, coming to rest in the narrow part -of the tube as in a barometer, so that the carbon rod was then in a -vacuum. One lamp terminal was the platinum wire extending through the -top of the tube, and the other was the mercury. Several of these lamps -were put on exhibition in London, but were not a commercial success -as they blackened very rapidly. Starr started his return trip to the -United States the next year, but died on board the ship when he was but -25 years old. - - - - -OTHER EARLY INCANDESCENT LAMPS - - -[Illustration: STAITE’S INCANDESCENT LAMP, 1848. - -The burner was of platinum and iridium.] - -[Illustration: ROBERTS’ INCANDESCENT LAMP, 1852. - -It had a graphite burner operating in vacuum.] - -In 1848 W. E. Staite, who two years previously had made an arc lamp, -invented an incandescent lamp. This consisted of a platinum-iridium -burner in the shape of an inverted U, covered by a glass globe. It had -a thumb screw for a switch, the whole device being mounted on a bracket -which was used for the return wire. E. C. Shepard, another Englishman, -obtained a patent two years later on an incandescent lamp consisting of -a weighted hollow charcoal cylinder the end of which pressed against a -charcoal cone. Current passing through this high resistance contact, -heated the charcoal to incandescence. It operated in a glass globe from -which the air could be exhausted. M. J. Roberts obtained an English -patent in 1852 on an incandescent lamp. This had a graphite rod for a -burner, which could be renewed, mounted in a glass globe. The globe was -cemented to a metallic cap fastened to a piece of pipe through which -the air could be exhausted. After being exhausted, the pipe, having a -stop cock, could be screwed on a stand to support the lamp. - -Moses G. Farmer, a professor at the Naval Training Station at Newport, -Rhode Island, lighted the parlor of his home at 11 Pearl Street, Salem, -Mass., during July, 1859, with several incandescent lamps having a -strip of platinum for the burner. The novel feature of this lamp was -that the platinum strip was narrower at the terminals than in the -center. Heat is conducted away from the terminals and by making the -burner thin at these points, the greater resistance of the ends of -the burner absorbed more electrical energy thus offsetting the heat -being conducted away. This made a more uniform degree of incandescence -throughout the length of the burner, and Prof. Farmer obtained a patent -on this principle many years later (1882). - -[Illustration: FARMER’S INCANDESCENT LAMP, 1859. - -This experimental platinum lamp was made by Professor Farmer and -several of them lighted the parlor of his home in Salem, Mass.] - - - - -FURTHER ARC LAMP DEVELOPMENTS - - -During the ten years, 1850 to 1860, several inventors developed arc -lamp mechanisms. Among them was M. J. Roberts, who had invented the -graphite incandescent lamp. In Roberts’ arc lamp, which he patented in -1852, the lower carbon was stationary. The upper carbon fitted snugly -into an iron tube. In the tube was a brass covered iron rod, which -by its weight could push the upper carbon down the tube so the two -carbons normally were in contact. An electro-magnet in series with the -arc was so located that, when energized, it pulled up the iron tube. -This magnet also held the brass covered iron rod from pushing the -upper carbon down the tube so that the two carbons were pulled apart, -striking the arc. When the arc went out, the iron tube dropped back -into its original position, the brass covered iron rod was released, -pushing the upper carbon down the tube until the two carbons again -touched. This closed the circuit again, striking the arc as before. - -[Illustration: ROBERTS’ ARC LAMP, 1852. - -The arc was controlled by an electro-magnet which held an iron tube to -which the upper carbon was fastened.] - -[Illustration: SLATER AND WATSON’S ARC LAMP, 1852. - -Clutches were used for the first time in this arc lamp to feed the -carbons.] - -In the same year (1852) Slater and Watson obtained an English patent -on an arc lamp in which the upper carbon was movable and held in place -by two clutches actuated by electro-magnets. The lower carbon was -fixed, and normally the two carbons touched each other. When current -was turned on, the electro-magnet lifted the clutches which gripped the -upper carbon, pulling it up and striking the arc. This was the first -time that a clutch was used to allow the carbon to feed as it became -consumed. - -Henry Chapman, in 1855, made an arc in which the upper carbon was -allowed to feed by gravity, but held in place by a chain wound around -a wheel. On this wheel was a brake actuated by an electro-magnet. The -lower carbon was pulled down by an electro-magnet working against a -spring. When no current was flowing or when the arc went out, the two -carbons touched. With current on, one electro-magnet set the brake and -held the upper carbon stationary. The other electro-magnet pulled the -lower carbon down, thus striking the arc. - -None of these mechanisms regulated the length of the arc. It was not -until 1856 that Joseph Lacassagne and Henry Thiers, Frenchmen, invented -the so-called “differential” method of control, which made the carbons -feed when the arc voltage, and hence length, became too great. This -principle was used in commercial arc lamps several years afterward when -they were operated on series circuits, as it had the added advantage -of preventing the feeding of one arc lamp affecting another on the -same circuit. This differential control consists in principle of two -electro-magnets, one in series with, and opposing the pull of the other -which is in shunt with the arc. The series magnet pulls the carbons -apart and strikes the arc. As the arc increases in length, its voltage -rises, thereby increasing the current flowing through the shunt magnet. -This increases the strength of the shunt magnet and, when the arc -becomes too long, the strength of the shunt becomes greater than that -of the series magnet, thus making the carbons feed. - -[Illustration: DIAGRAM OF “DIFFERENTIAL” METHOD OF CONTROL OF AN ARC -LAMP. - -This principle, invented by Lacassagne and Thiers, was used in all arc -lamps when they were commercially introduced on a large scale more than -twenty years later.] - -The actual method adopted by Lacassagne and Thiers was different from -this, but it had this principle. They used a column of mercury on -which the lower carbon floated. The upper carbon was stationary. The -height of the mercury column was regulated by a valve connected with -a reservoir of mercury. The pull of the series magnet closed the valve -fixing the height of the column. The pull of the shunt magnet tended -to open the valve, and when it overcame the pull of the series magnet -it allowed mercury to flow from the reservoir, raising the height of -the column bringing the carbons nearer together. This reduced the -arc voltage and shunt magnet strength until the valve closed again. -Thus the carbons were always kept the proper distance apart. In first -starting the arc, or if the arc should go out, current would only flow -through the shunt magnet, bringing the two carbons together until they -touched. Current would then flow through the contact of the two carbons -and through the series magnet, shutting the valve. There were no means -of pulling the carbons apart to strike the arc. Current flowing through -the high resistance of the poor contact of the two carbons, heated -their tips to incandescence. The incandescent tips would begin to burn -away, thus after a time starting an arc. The arc, however, once started -was maintained the proper length. - -[Illustration: LACASSAGNE AND THIERS’ DIFFERENTIALLY CONTROLLED ARC -LAMP, 1856. - -The lower carbon floated on a column of mercury whose height was -“differentially” controlled by series and shunt magnets.] - -In 1857, Serrin took out his first patent on an arc lamp, the general -principles of which were the same as in others he made. The mechanism -consisted of two drums, one double the diameter of the other. Both -carbons were movable, the upper one feeding down, and the lower one -feeding up, being connected with chains wound around the drums. The -difference in consumption of the two carbons was therefore compensated -for by the difference in size of the drums, thus maintaining the -location of the arc in a fixed position. A train of wheels controlled -by a pawl and regulated by an electro-magnet, controlled the movement -of the carbons. The weight of the upper carbon and its holder actuates -the train of wheels. - -[Illustration: SERRIN’S ARC LAMP, 1857. - -This type of arc was not differentially controlled but was the first -commercial lamp later used. Both carbons were movable, held by chains -wound around drums which were controlled by ratchets actuated by an -electro-magnet.] - - - - -DEVELOPMENT OF THE DYNAMO, 1840–1860 - - -During the first few years after 1840 the dynamo was only a laboratory -experiment. Woolrich devised a machine which had several pairs of -magnets and double the number of coils in order to make the current -obtained less pulsating. Wheatstone in 1845 patented the use of -electro-magnets in place of permanent magnets. Brett in 1848 suggested -that the current, generated in the coils, be allowed to flow through -a coil surrounding each permanent magnet to further strengthen the -magnets. Pulvermacher in 1849 proposed the use of thin plates of iron -for the bobbins, to reduce the eddy currents generated in the iron. -Sinsteden in 1851 suggested that the current from a permanent magnet -machine be used to excite the field coils of an electro-magnet machine. - -In 1855 Soren Hjorth, of Copenhagen, Denmark, patented a dynamo having -both permanent and electro-magnets, the latter being excited by -currents first induced in the bobbins by the permanent magnets. In 1856 -Dr. Werner Siemens invented the shuttle wound armature. This consisted -of a single coil of wire wound lengthwise and counter sunk in a long -cylindrical piece of iron. This revolved between the magnet poles which -were shaped to fit the cylindrical armature. - -[Illustration: SIEMENS’ DYNAMO, 1856. - -This dynamo was an improvement over others on account of the -construction of its “shuttle” armature.] - - - - -THE FIRST COMMERCIAL INSTALLATION OF AN ELECTRIC LIGHT - - -In 1862 a Serrin type of arc lamp was installed in the Dungeness -lighthouse in England. Current was supplied by a dynamo made by the -Alliance Company, which had been originally designed in 1850 by Nollet, -a professor of Physics in the Military School in Brussels. Nollet’s -original design was of a dynamo having several rows of permanent -magnets mounted radially on a stationary frame, with an equal number -of bobbins mounted on a shaft which rotated and had a commutator so -direct current could be obtained. A company was formed to sell hydrogen -gas for illuminating purposes, the gas to be made by the decomposition -of water with current from this machine. Nollet died and the company -failed, but it was reorganized as the Alliance Company a few years -later to exploit the arc lamp. - -[Illustration: ALLIANCE DYNAMO, 1862. - -This was the dynamo used in the first commercial installation of an arc -light in the Dungeness Lighthouse, England, 1862.] - -About the only change made in the dynamo was to substitute collector -rings for the commutator to overcome the difficulties of commutation. -Alternating current was therefore generated in this first commercial -machine. It had a capacity for but one arc light, which probably -consumed less than ten amperes at about 45 volts, hence delivered -in the present terminology not over 450 watts or about two-thirds -of a horsepower. As the bobbins of the armature undoubtedly had a -considerable resistance, the machine had an efficiency of not over 50 -per cent and therefore required at least one and a quarter horsepower -to drive it. - - - - -FURTHER DYNAMO DEVELOPMENTS - - -In the summer of 1886 Sir Charles Wheatstone constructed a self-excited -machine on the principle of using the residual magnetism in the field -poles to set up a feeble current in the armature which, passing through -the field coils, gradually strengthened the fields until they built up -to normal strength. It was later found that this idea had been thought -of by an unknown man, being disclosed by a clause in a provisional -1858 English patent taken out by his agent. Wheatstone’s machine was -shown to the Royal Society in London and a paper on it read before the -Society on February 14, 1867. The field coils were shunt wound. - -[Illustration: WHEATSTONE’S SELF-EXCITED DYNAMO, 1866. - -This machine was the first self-excited dynamo by use of the residual -magnetism in the field poles.] - -Dr. Werner Siemens also made a self-excited machine, having series -fields, a paper on which was read before the Academy of Sciences -in Berlin on January 17, 1867. This paper was forwarded to the -Royal Society in London and presented at the same meeting at which -Wheatstone’s dynamo was described. Wheatstone probably preceded Siemens -in this re-discovery of the principle of self-excitation, but both are -given the merit of it. However, S. A. Varley on December 24, 1866, -obtained a provisional English patent on this, which was not published -until July, 1867. - -[Illustration: GRAMME’S DYNAMO, 1871. - -These were commercially used, their main feature being the “ring” wound -armature.] - -[Illustration: GRAMME’S “RING” ARMATURE. - -Wire coils, surrounding an iron wire core, were all connected together -in an endless ring, each coil being tapped with a wire connected to a -commutator bar.] - -In 1870 Gramme, a Frenchman, patented his well-known ring armature. The -idea had been previously thought of by Elias, a Hollander, in 1842, and -by Pacinnotti, an Italian, as shown by the crude motors (not dynamos) -they had made. Gramme’s armature consisted of an iron wire core coated -with a bituminous compound in order to reduce the eddy currents. This -core was wound with insulated wire coils, all connected together in -series as one single endless coil. Each coil was tapped with a wire -connected to a commutator bar. His first machine, having permanent -magnets for fields, was submitted to the French Academy of Sciences in -1871. Later machines were made with self-excited field coils, which -were used in commercial service. They had, however a high resistance -armature, so that their efficiency did not exceed 50 per cent. - -[Illustration: ALTENECK’S DYNAMO WITH “DRUM” WOUND ARMATURE, 1872. - -The armature winding was entirely on the surface of the armature core, -a principle now used in all dynamos.] - -Von Hefner Alteneck, an engineer with Siemens, invented the drum wound -armature in 1872. The wires of the armature were all on the surface -of the armature core, the wires being tapped at frequent points for -connection with the commutator bars. Thus in the early seventies, -commercial dynamos were available for use in arc lighting, and a few -installations were made in Europe. - - - - -RUSSIAN INCANDESCENT LAMP INVENTORS - - -In 1872 Lodyguine, a Russian scientist, made an incandescent lamp -consisting of a “V” shaped piece of graphite for a burner, which -operated in nitrogen gas. He lighted the Admiralty Dockyard at St. -Petersburg with about two hundred of these lamps. In 1872 the Russian -Academy of Sciences awarded him a prize of 50,000 rubles (a lot of -real money at that time) for his invention. A company with a capital -of 200,000 rubles (then equal to about $100,000) was formed but as -the lamp was so expensive to operate and had such a short life, about -twelve hours, the project failed. - -[Illustration: LODYGUINE’S INCANDESCENT LAMP, 1872. - -The burner was made of graphite and operated in nitrogen gas.] - -[Illustration: KONN’S INCANDESCENT LAMP, 1875. - -In this lamp the graphite rods operated in a vacuum.] - -Kosloff, another Russian, in 1875 patented a graphite in nitrogen -incandescent lamp, which had several graphite rods for burners, so -arranged that when one failed another was automatically connected. -Konn, also a Russian, made a lamp similar to Kosloff’s except that -the graphite rods operated in a vacuum. Bouliguine, another Russian, -in 1876 made an incandescent lamp having a long graphite rod, only -the upper part of which was in circuit. As this part burned out, the -rod was automatically pushed up so that a fresh portion then was in -circuit. It operated in a vacuum. None of these lamps was commercial as -they blackened rapidly and were too expensive to maintain. - -[Illustration: BOULIGUINE’S INCANDESCENT LAMP, 1876. - -A long graphite rod, the upper part of which only was in circuit, -operated in vacuum. As this part burned out, the rod was automatically -shoved up, a fresh portion then being in the circuit.] - - - - -THE JABLOCHKOFF “CANDLE” - - -Paul Jablochkoff was a Russian army officer and an engineer. In the -early seventies he came to Paris and developed a novel arc light. This -consisted of a pair of carbons held together side by side and insulated -from each other by a mineral known as kaolin which vaporized as the -carbons were consumed. There was no mechanism, the arc being started -by a thin piece of carbon across the tips of the carbons. Current -burned this bridge, starting the arc. The early carbons were about -five inches long, and the positive carbon was twice as thick as the -negative to compensate for the unequal consumption on direct current. -This, however, did not work satisfactorily. Later the length of the -carbons was increased, the carbon made of equal thickness and burned -on alternating current of about eight or nine amperes at about 45 -volts. He made an alternating current generator which had a stationary -exterior armature with interior revolving field poles. Several -“candles,” as they were called, were put in one fixture to permit all -night service and an automatic device was developed, located in each -fixture, so that should one “candle” go out for any reason, another was -switched into service. - -[Illustration: JABLOCHKOFF “CANDLE,” 1876. - -This simple arc consisted of a pair of carbons held together side by -side and insulated from each other by kaolin. Several boulevards in -Paris were lighted with these arc lights. This arc lamp is in the -collection of the Smithsonian Institution.] - -In 1876 many of these “candles” were installed and later several of the -boulevards in Paris were lighted with them. This was the first large -installation of the arc light, and was the beginning of its commercial -introduction. Henry Wilde made some improvements in the candle by -eliminating the kaolin between the carbons which gave Jablochkoff’s arc -its peculiar color. Wilde’s arc was started by allowing the ends of the -carbons to touch each other, a magnet swinging them apart thus striking -the arc. - -[Illustration: JABLOCHKOFF’S ALTERNATING CURRENT DYNAMO, 1876. - -This dynamo had a stationary exterior armature and internal revolving -field poles. Alternating current was used for the Jablochkoff “candle” -to overcome the difficulties of unequal consumption of the carbons on -direct current.] - - -COMMERCIAL INTRODUCTION OF THE DIFFERENTIALLY CONTROLLED ARC LAMP - -About the same time Lontin, a Frenchman, improved Serrin’s arc lamp -mechanism by the application of series and shunt magnets. This is the -differential principle which was invented by Lacassagne and Thiers in -1855 but which apparently had been forgotten. Several of these lamps -were commercially installed in France beginning with 1876. - - - - -ARC LIGHTING IN THE UNITED STATES - - -[Illustration: WALLACE-FARMER ARC LAMP, 1875. - -This “differentially controlled” arc lamp consisted of two slabs of -carbon between which the arc played. In the original lamp the carbon -slabs were mounted on pieces of wood held in place by bolts, adjustment -being made by hitting the upper carbon slab with a hammer. This lamp is -in the collection of the Smithsonian Institution.] - -[Illustration: WALLACE-FARMER DYNAMO, 1875. - -This was the first commercial dynamo used in the United States for -arc lighting. This dynamo is in the collection of the Smithsonian -Institution.] - -About 1875 William Wallace of Ansonia, Connecticut, made an arc light -consisting of two rectangular carbon plates mounted on a wooden frame. -The arc played between the two edges of the plates, which lasted much -longer than rods. When the edges had burned away so that the arc then -became unduly long, the carbon plates were brought closer together by -hitting them with a hammer. Wallace became associated with Moses G. -Farmer, and they improved this crude arc by fastening the upper carbon -plate to a rod which was held by a clutch controlled by a magnet. This -magnet had two coils in one, the inner winding in series with the arc, -and outer one in shunt and opposing the series winding. The arc was -therefore differentially controlled. - -[Illustration: WESTON’S ARC LAMP, 1876. - -This lamp is in the collection of the Smithsonian Institution.] - -They also developed a series wound direct current dynamo. The armature -consisted of a number of bobbins, all connected together in an endless -ring. Each bobbin was also connected to a commutator bar. There were -two sets of bobbins, commutators and field poles, the equivalent of two -machines in one, which could be connected either to separate circuits, -or together in series on one circuit. The Wallace-Farmer system was -commercially used. The arc consumed about 20 amperes at about 35 volts, -but as the carbon plates cooled the arc, the efficiency was poor. -The arc flickered back and forth on the edges of the carbons casting -dancing shadows. The carbons, while lasting about 50 hours, were not -uniform in density, so the arc would flare up and cast off soot and -sparks. - -Edward Weston of Newark, New Jersey, also developed an arc lighting -system. His commercial lamp had carbon rods, one above the other, and -the arc was also differentially controlled. An oil dash pot prevented -undue pumping of the carbons. His dynamo had a drum-wound armature, and -had several horizontal field coils on each side of one pair of poles -between which the armature revolved. The system was designed for about -20 amperes, each are taking about 35 volts. - -[Illustration: BRUSH’S DYNAMO, 1877. - -This dynamo was used for many years for commercial arc lighting.] - -[Illustration: DIAGRAM OF BRUSH ARMATURE. - -The armature was not a closed circuit. For description of its -operation, see text.] - -Charles F. Brush made a very successful arc lighting system in 1878. -His dynamo was unique in that the armature had eight coils, one end of -each pair of opposite coils being connected together and the other ends -connected to a commutator segment. Thus the armature itself was not a -closed circuit. The machine had two pairs of horizontal poles between -which the coils revolved. One end of the one pair of coils in the most -active position was connected, by means of two of the four brushes, -in series with one end of the two pairs of coils in the lesser active -position. The latter two pairs of coils were connected in multiple -with each other by means of the brushes touching adjacent commutator -segments. The outside circuit was connected to the other two brushes, -one of which was connected to the other end of the most active pair -of coils. The other brush was connected to the other end of the two -lesser active pairs of coils. The one pair of coils in the least active -position was out of circuit. The field coils were connected in series -with the outside circuit. - -[Illustration: BRUSH’S ARC LAMP, 1877. - -The carbons were differentially controlled. This lamp was used for many -years. This lamp is in the collection of the Smithsonian Institution.] - -Brush’s arc lamp was also differentially controlled. It was designed -for about 10 amperes at about 45 volts. The carbons were copper -plated to increase their conductivity. Two pairs of carbons were used -for all-night service, each pair lasting about eight hours. A very -simple device was used to automatically switch the arc from one to -the other pair of carbons, when the first pair was consumed. This -device consisted of a triangular-shaped piece of iron connected to the -solenoid controlling the arc. There was a groove on each of the outer -two corners of this triangle, one groove wider than the other. An iron -washer surrounded each upper carbon. The edge of each washer rested -in a groove. The washer in the narrow groove made a comparatively -tight fit about its carbon. The other washer in the wider groove had -a loose fit about its carbon. Pins prevented the washer from falling -below given points. Both pairs of carbons touched each other at the -start. When current was turned on, the solenoid lifted the triangle, -the loose-fitting washer gripped its carbon first, so that current then -only passed through the other pair of carbons which were still touching -each other. The further movement of the solenoid then separated these -carbons, the arc starting between them. When this pair of carbons -became consumed, they could not feed any more so that the solenoid -would then allow the other pair of carbons to touch, transferring the -arc to that pair. - -[Illustration: THOMSON-HOUSTON ARC DYNAMO, 1878. - -This dynamo was standard for many years. This machine is in the -collection of the Smithsonian Institution.] - -Elihu Thomson and Edwin J. Houston in 1878 made a very successful and -complete arc light system. Their dynamo was specially designed to fit -the requirements of the series arc lamp. The Thomson-Houston machine -was a bipolar, having an armature consisting of three coils, one end of -each of the three coils having a common terminal, or “Y” connected, as -it is called. The other end of each coil was connected to a commutator -segment. The machine was to a great extent self-regulating, that is the -current was inherently constant with fluctuating load, as occurs when -the lamps feed or when the number of lamps burning at one time should -change for any reason. This regulation was accomplished by what is -called “armature reaction,” which is the effect the magnetization of -the armature has on the field strength. Close regulation was obtained -by a separate electro-magnet, in series with the circuit, which shifted -the brushes as the load changed. As there were but three commutator -segments, one for each coil, excessive sparking was prevented by an air -blast. - -[Illustration: DIAGRAM OF T-H ARC LIGHTING SYSTEM.] - -The “T-H” (Thompson-Houston) lamp employed the shunt feed principle. -The carbons were normally separated, being in most types drawn apart -by a spring. A high resistance magnet, shunted around the arc, served -to draw the carbons together. This occurred on starting the lamp and -thereafter the voltage of the arc was held constant by the balance -between the spring and the shunt magnet. As the carbon burned away the -mechanism advanced to a point where a clutch was tripped, the carbons -brought together, and the cycle repeated. Both the T-H and Brush -systems were extensively used in street lighting, for which they were -the standard when the open arc was superseded by the enclosed. - - - - -OTHER AMERICAN ARC LIGHT SYSTEMS - - -[Illustration: THOMSON-HOUSTON ARC LAMP, 1878. - -This is an early model with a single pair of carbons.] - -[Illustration: THOMSON DOUBLE CARBON ARC LAMP. - -This later model, having two pairs of carbons, was commercially used -for many years. This lamp is in the collection of the Smithsonian -Institution.] - -Beginning with about 1880, several arc light systems were developed. -Among these were the Vanderpoele, Hochausen, Waterhouse, Maxim, -Schuyler and Wood. The direct current carbon arc is inherently more -efficient than the alternating current lamp, owing to the fact that the -continuous flow of current in one direction maintains on the positive -carbon a larger crater at the vaporizing point of carbon. This source -furnishes the largest proportion of light, the smaller crater in the -negative carbon much less. With the alternating current arc, the large -crater is formed first on the upper and then on the lower carbon. On -account of the cooling between alternations, the mean temperature falls -below the vaporizing point of carbon, thus accounting for the lower -efficiency of the alternating current arc. - -[Illustration: MAXIM DYNAMO. - -This dynamo is in the collection of the Smithsonian Institution.] - -For this reason all these systems used direct current and the 10 ampere -ultimately displaced the 20 ampere system. The 10 ampere circuit -was later standardized at 9.6 amperes, 50 volts per lamp. The lamp -therefore consumed 480 watts giving an efficiency of about 15 lumens -per watt. This lamp gave an average of 575 candlepower (spherical) in -all directions, though it was called the 2000 cp (candlepower) arc as -under the best possible conditions it could give this candlepower in -one direction. Later a 6.6 ampere arc was developed. This was called -the “1200 cp” lamp and was not quite as efficient as the 9.6 ampere -lamp. - - - - -“SUB-DIVIDING THE ELECTRIC LIGHT” - - -While the arc lamp was being commercially established, it was at once -seen that it was too large a unit for household use. Many inventors -attacked the problem of making a smaller unit, or, as it was called, -“sub-dividing the electric light.” In the United States there were four -men prominent in this work: William E. Sawyer, Moses G. Farmer, Hiram -S. Maxim and Thomas A. Edison. These men did not make smaller arc lamps -but all attempted to make an incandescent lamp that would operate on -the arc circuits. - -[Illustration: SAWYER’S INCANDESCENT LAMP, 1878. - -This had a graphite burner operating in nitrogen gas.] - -[Illustration: FARMER’S INCANDESCENT LAMP, 1878. - -The graphite burner operated in nitrogen gas. This lamp is in the -collection of the Smithsonian Institution.] - -Sawyer made several lamps in the years 1878–79 along the lines of the -Russian scientists. All his lamps had a thick carbon burner operating -in nitrogen gas. They had a long glass tube closed at one end and the -other cemented to a brass base through which the gas was put in. Heavy -fluted wires connected the burner with the base to radiate the heat, -in order to keep the joint in the base cool. The burner was renewable -by opening the cemented joint. Farmer’s lamp consisted of a pair of -heavy copper rods mounted on a rubber cork, between which a graphite -rod was mounted. This was inserted in a glass bulb and operated in -nitrogen gas. Maxim made a lamp having a carbon burner operating in a -rarefied hydrocarbon vapor. He also made a lamp consisting of a sheet -of platinum operating in air. - - - - -EDISON’S INVENTION OF A PRACTICAL INCANDESCENT LAMP - - -Edison began the study of the problem in the spring of 1878. He had a -well-equipped laboratory at Menlo Park, New Jersey, with several able -assistants and a number of workmen, about a hundred people all told. -He had made a number of well-known inventions, among which were the -quadruplex telegraph whereby four messages could be sent simultaneously -over one wire, the carbon telephone transmitter without which Bell’s -telephone receiver would have been impracticable, and the phonograph. -All of these are in use today, so Edison was eminently fitted to attack -the problem. - -[Illustration: MAXIM’S INCANDESCENT LAMP, 1878. - -The carbon burner operated in a rarefied hydrocarbon vapor. This lamp -is in the collection of the Smithsonian Institution.] - -Edison’s first experiments were to confirm the failures of other -experimenters. Convinced of the seeming impossibility of carbon, he -turned his attention to platinum as a light giving element. Realizing -the importance of operating platinum close to its melting temperature, -he designed a lamp which had a thermostatic arrangement so that -the burner would be automatically short circuited the moment its -temperature became dangerously close to melting. The burner consisted -of a double helix of platinum wire within which was a rod. When the -temperature of the platinum became too high, the rod in expanding -would short circuit the platinum. The platinum cooled at once, the -rod contracted opening the short circuit and allowing current to flow -through the burner again. His first incandescent lamp patent covered -this lamp. His next patent covered a similar lamp with an improved -thermostat consisting of an expanding diaphragm. Both of these lamps -were designed for use on series circuits. - -[Illustration: EDISON’S FIRST EXPERIMENTAL LAMP, 1878. - -The burner was a coil of platinum wire which was protected from -operating at too high a temperature by a thermostat.] - -The only system of distributing electricity, known at that time, was -the series system. In this system current generated in the dynamo -armature flowed through the field coils, out to one lamp after another -over a wire, and then back to the dynamo. There were no means by which -one lamp could be turned on and off without doing the same with all the -others on the circuit. Edison realized that while this was satisfactory -for street lighting where arcs were generally used, it never would -be commercial for household lighting. He therefore decided that a -practical incandescent electric lighting system must be patterned -after gas lighting with which it would compete. He therefore made -an intensive study of gas distribution and reasoned that a constant -pressure electrical system could be made similar to that of gas. - -The first problem was therefore to design a dynamo that would give a -constant pressure instead of constant current. He therefore reasoned -that the internal resistance of the armature must be very low or the -voltage would fall as current was taken from the dynamo. Scientists -had shown that the most economical use of electricity from a primary -battery was where the external resistance of the load was the same as -the internal resistance of the battery, or in other words, 50 per cent -was the maximum possible efficiency. - -[Illustration: DIAGRAM OF CONSTANT CURRENT SERIES SYSTEM. - -This, in 1878, was the only method of distributing electric current.] - -[Illustration: DIAGRAM OF EDISON’S MULTIPLE SYSTEM, 1879. - -Edison invented the multiple system of distributing electric current, -now universally used.] - -When Edison proposed a very low resistance armature so that the dynamo -would have an efficiency of 90 per cent at full load, he was ridiculed. -Nevertheless he went ahead and made one which attained this. The -armature consisted of drum-wound insulated copper rods, the armature -core having circular sheets of iron with paper between to reduce the -eddy currents. There were two vertical fields above and connected in -shunt with the armature. It generated electricity at about a hundred -volts constant pressure and could supply current up to about 60 -amperes at this pressure. It therefore had a capacity, in the present -terminology, of about 6 kilowatts (or 8 horsepower). - -[Illustration: EDISON DYNAMO, 1879. - -Edison made a dynamo that was 90 per cent efficient which scientists -said was impossible. This dynamo is in the collection of the -Smithsonian Institution and was one of the machines on the steamship -Columbia, the first commercial installation of the Edison lamp.] - -A multiple system of distribution would make each lamp independent of -every other and with a dynamo made for such a system, the next thing -was to design a lamp for it. Having a pressure of about a hundred volts -to contend with, the lamp, in order to take a small amount of current, -must, to comply with Ohm’s law, have a high resistance. He therefore -wound many feet of fine platinum wire on a spool of pipe clay and -made his first high resistance lamp. He used his diaphragm thermostat -to protect the platinum from melting, and, as now seems obvious but -was not to all so-called electricians at that time, the thermostat -was arranged to open circuit instead of short circuit the burner when -it became too hot. This lamp apparently solved the problem, and, in -order to protect the platinum from the oxygen of the air, he coated -it with oxide of zirconium. Unfortunately zirconia, while an insulator -at ordinary temperatures, becomes, as is now known, a conductor of -electricity when heated, so that the lamp short circuited itself when -it was lighted. - -[Illustration: EDISON’S HIGH RESISTANCE PLATINUM LAMP, 1879. - -This lamp had a high resistance burner, necessary for the multiple -system.] - -[Illustration: EDISON’S HIGH RESISTANCE PLATINUM IN VACUUM LAMP, 1879. - -This experimental lamp led to the invention of the successful carbon -filament lamp.] - -During his experiments he had found that platinum became exceedingly -hard after it had been heated several times to incandescence by current -flowing through it. This apparently raised its melting temperature so -he was able to increase the operating temperature and therefore greatly -increase the candlepower of his lamps after they had been heated a few -times. Examination of the platinum under a microscope showed it to be -much less porous after heating, so he reasoned that gases were occluded -throughout the platinum and were driven out by the heat. This led him -to make a lamp with a platinum wire to operate in vacuum, as he thought -that more of the occluded gases would come out under such circumstances. - -[Illustration: EDISON’S CARBON LAMP OF OCTOBER 21, 1879. - -This experimental lamp, having a high resistance carbon filament -operating in a high vacuum maintained by an all-glass globe, was the -keystone of Edison’s successful incandescent lighting system. All -incandescent lamps made today embody the basic features of this lamp. -This replica is in the Smithsonian Institution exhibit of Edison lamps. -The original was destroyed.] - -These lamps were expensive to make, and, knowing that he could get the -requisite high resistance at much less cost from a long and slender -piece of carbon, he thought he might be able to make the carbon last -in the high vacuum he had been able to obtain from the newly invented -Geissler and Sprengel mercury air pumps. After several trials he -finally was able to carbonize a piece of ordinary sewing thread. This -he mounted in a one-piece all glass globe, all joints fused by melting -the glass together, which he considered was essential in order to -maintain the high vacuum. Platinum wires were fused in the glass to -connect the carbonized thread inside the bulb with the circuit outside -as platinum has the same coefficient of expansion as glass and hence -maintains an airtight joint. He reasoned that there would be occluded -gases in the carbonized thread which would immediately burn up if the -slightest trace of oxygen were present, so he heated the lamp while it -was still on the exhaust pump after a high degree of vacuum had been -obtained. This was accomplished by passing a small amount of current -through the “filament,” as he called it, gently heating it. Immediately -the gases started coming out, and it took eight hours more on the pump -before they stopped. The lamp was then sealed and ready for trial. - -[Illustration: DEMONSTRATION OF EDISON’S INCANDESCENT LIGHTING SYSTEM. - -Showing view of Menlo Park Laboratory Buildings, 1880.] - -On October 21, 1879, current was turned into the lamp and it lasted -forty-five hours before it failed. A patent was applied for on November -4th of that year and granted January 27, 1880. All incandescent lamps -made today embody the basic features of this lamp. Edison immediately -began a searching investigation of the best material for a filament and -soon found that carbonized paper gave several hundred hours life. This -made it commercially possible, so in December, 1879, it was decided -that a public demonstration of his incandescent lighting system should -be made. Wires were run to several houses in Menlo Park, N. J., and -lamps were also mounted on poles, lighting the country roads in the -neighborhood. An article appeared in the New York Herald on Sunday, -December 21, 1879, describing Edison’s invention and telling of the -public demonstration to be given during the Christmas holidays. This -occupied the entire first page of the paper, and created such a furor -that the Pennsylvania Railroad had to run special trains to Menlo -Park to accommodate the crowds. The first commercially successful -installation of the Edison incandescent lamps and lighting system was -made on the steamship Columbia, which started May 2, 1880, on a voyage -around Cape Horn to San Francisco, Calif. - -The carbonized paper filament of the first commercial incandescent lamp -was quite fragile. Early in 1880 carbonized bamboo was found to be not -only sturdy but made an even better filament than paper. The shape of -the bulb was also changed from round to pear shape, being blown from -one inch tubing. Later the bulbs were blown directly from molten glass. - -[Illustration: DYNAMO ROOM, S. S. COLUMBIA. - -The first commercial installation of the Edison Lamp, started May 2, -1880. One of these original dynamos is on exhibit at the Smithsonian -Institution.] - -As it was inconvenient to connect the wires to the binding posts of -a new lamp every time a burned out lamp had to be replaced, a base -and socket for it were developed. The earliest form of base consisted -simply of bending the two wires of the lamp back on the neck of the -bulb and holding them in place by wrapping string around the neck. The -socket consisted of two pieces of sheet copper in a hollow piece of -wood. The lamp was inserted in this, the two-wire terminals of the lamp -making contact with the two-sheet copper terminals of the socket, the -lamp being rigidly held in the socket by a thumb screw which forced -the socket terminals tight against the neck of the bulb. - -[Illustration: ORIGINAL SOCKET FOR INCANDESCENT LAMPS, 1880.] - -[Illustration: WIRE TERMINAL BASE LAMP, 1880. - -This crude form of lamp base fitted the original form of lamp socket -pictured above. This lamp is in the exhibit of Edison lamps in the -Smithsonian Institution.] - -This crude arrangement was changed in the latter part of 1880 to a -screw shell and a ring for the base terminals, wood being used for -insulation. The socket was correspondingly changed. This was a very -bulky affair, so the base was changed to a cone-shaped ring and a -screw shell for terminals. Wood was used for insulation, which a short -time after was changed to plaster of Paris as this was also used to -fasten the base to the bulb. It was soon found that the tension created -between the two terminals of the base when the lamp was firmly screwed -in the socket often caused the plaster base to pull apart, so the shape -of the base was again changed early in 1881, to the form in use today. - -An improved method of connecting the ends of the filament to the -leading-in wires was adopted early in 1881. Formerly this was -accomplished by a delicate clamp having a bolt and nut. The improvement -consisted of copper plating the filament to the leading-in wire. - -[Illustration: ORIGINAL SCREW BASE LAMP, 1880. - -This first screw base, consisting of a screw shell and ring for -terminals with wood for insulation, was a very bulky affair. This lamp -is in the exhibit of Edison lamps in the Smithsonian Institution.] - -[Illustration: IMPROVED SCREW BASE LAMP, 1881. - -The terminals of this base consisted of a cone shaped ring and a screw -shell. At first wood was used for insulation, later plaster of paris -which was also used to fasten the base to the bulb. This lamp is in the -exhibit of Edison lamps in the Smithsonian Institution.] - -In the early part of the year 1881 the lamps were made “eight to -the horsepower.” Each lamp, therefore, consumed a little less than -100 watts, and was designed to give 16 candlepower in a horizontal -direction. The average candlepower (spherical) in all directions was -about 77 per cent of this, hence as the modern term “lumen” is 12.57 -spherical candlepower, these lamps had an initial efficiency of about -1.7 lumens per watt. The lamps blackened considerably during their life -so that just before they burned out their candlepower was less than -half that when new. Thus their mean efficiency throughout life was -about 1.1 l-p-w (lumens per watt). These figures are interesting in -comparison with the modern 100-watt gas-filled tungsten-filament lamp -which has an initial efficiency of 12.9, and a mean efficiency of 11.8, -l-p-w. In other words the equivalent (wattage) size of modern lamp -gives over seven times when new, and eleven times on the average, as -much light for the same energy consumption as Edison’s first commercial -lamp. In the latter part of 1881 the efficiency was changed to “ten -lamps per horsepower,” equivalent to 2¼ l-p-w initially. Two sizes of -lamps were made: 16 cp for use on 110-volt circuits and 8 cp for use -either direct on 55 volts or two in series on 110-volt circuits. - -[Illustration: FINAL FORM OF SCREW BASE, 1881. - -With plaster of paris, the previous form of base was apt to pull apart -when the lamp was firmly screwed into the socket. The form of the base -was therefore changed to that shown, which overcame these difficulties, -and which has been used ever since. The lamp shown was standard for -three years and is in the exhibit of Edison lamps in the Smithsonian -Institution.] - - - - -EDISON’S THREE-WIRE SYSTEM - - -The distance at which current can be economically delivered at 110 -volts pressure is limited, as will be seen from a study of Ohm’s law. -The loss of power in the distributing wires is proportional to the -square of the current flowing. If the voltage be doubled, the amount -of current is halved, for a given amount of electric power delivered, -so that the size of the distributing wires can then be reduced to -one-quarter for a given loss in them. At that time (1881) it was -impossible to make 220-volt lamps, and though they are now available, -their use is uneconomical, as their efficiency is much poorer than that -of 110-volt incandescent lamps. - -Edison invented a distributing system that had two 110-volt circuits, -with one wire called the neutral, common to both circuits so that the -pressure on the two outside wires was 220 volts. The neutral wire had -only to be large enough to carry the difference between the currents -flowing in the two circuits. As the load could be so arranged that it -would be approximately equal at all times on both circuits, the neutral -wire could be relatively small in size. Thus the three-wire system -resulted in a saving of 60 per cent in copper over the two-wire system -or, for the same amount of copper, the distance that current could be -delivered was more than doubled. - -[Illustration: DIAGRAM OF EDISON’S THREE-WIRE SYSTEM, 1881. - -This system reduced the cost of copper in the multiple distributing -system 60 per cent.] - - -DEVELOPMENT OF THE ALTERNATING CURRENT CONSTANT POTENTIAL SYSTEM - -The distance that current can be economically distributed, as has -been shown, depends upon the voltage used. If, therefore, current -could be sent out at a high voltage and the pressure brought down to -that desired at the various points to which it is distributed, such -distribution could cover a much greater area. Lucien Gaulard was a -French inventor and was backed by an Englishman named John D. Gibbs. -About 1882 they patented a series alternating-current system of -distribution. They had invented what is now called a transformer which -consisted of two separate coils of wire mounted on an iron core. All -the primary coils were connected in series, which, when current went -through them, induced a current in the secondary coils. Lamps were -connected in multiple on each of the secondary coils. An American -patent was applied for on the transformer, but was refused on the basis -that “more current cannot be taken from it than is put in.” While -this is true if the word energy were used, the transformer can supply -a greater current at a lower voltage (or vice versa) than is put in, -the ratio being in proportion to the relative number of turns in the -primary and secondary coils. The transformer was treated with ridicule -and Gaulard died under distressing circumstances. - -[Illustration: DIAGRAM OF STANLEY’S ALTERNATING CURRENT MULTIPLE -SYSTEM, 1885. - -This system is now universally used for distributing electric current -long distances.] - -Information regarding the transformer came to the attention of -William Stanley, an American, in the latter part of 1885. He made an -intensive study of the scheme, and developed a transformer in which -the primary coil was connected in multiple on a constant potential -alternating-current high-voltage system. From the secondary coil a -lower constant voltage was obtained. An experimental installation -was made at Great Barrington, Mass., in the early part of 1886, the -first commercial installation being made in Buffalo, New York, in the -latter part of the year. This scheme enabled current to be economically -distributed to much greater distances. The voltage of the high-tension -circuit has been gradually increased as the art has progressed from -about a thousand volts to over two hundred thousand volts pressure in a -recent installation in California, where electric power is transmitted -over two hundred miles. - - - - -INCANDESCENT LAMP DEVELOPMENTS, 1884–1894 - - -In 1884 the ring of plaster around the top of the base was omitted; in -1886 an improvement was made by pasting the filament to the leading-in -wires with a carbon paste instead of the electro-plating method; and -in 1888 the length of the base was increased so that it had more -threads. Several concerns started making incandescent lamps, the -filaments being made by carbonizing various substances. “Parchmentized” -thread consisted of ordinary thread passed through sulphuric acid. -“Tamadine” was cellulose in the sheet form, punched out in the shape -of the filament. Squirted cellulose in the form of a thread was also -used. This was made by dissolving absorbent cotton in zinc chloride, -the resulting syrup being squirted through a die into alcohol which -hardened the thread thus formed. This thread was washed in water, dried -in the air and then cut to proper length and carbonized. - -[Illustration: STANDARD EDISON LAMP, 1884. - -The ring of plaster around the neck of previous lamps was omitted. This -lamp is in the exhibit of Edison lamps in the Smithsonian Institution.] - -[Illustration: STANDARD EDISON LAMP, 1888. - -The length of the base was increased so it had more threads. This lamp -is in the exhibit of Edison lamps in the Smithsonian Institution.] - -The filament was improved by coating it with graphite. One method, -adopted about 1888, was to dip it in a hydrocarbon liquid before -carbonizing. Another, more generally adopted in 1893 was a process -originally invented by Sawyer, one of the Americans who had attempted -to “sub-divide the electric light” in 1878–79. This process consisted -of passing current through a carbonized filament in an atmosphere of -hydrocarbon vapor. The hot filament decomposed the vapor, depositing -graphite on the filament. The graphite coated filament improved it so -it could operate at 3½ lumens per watt (initial efficiency). Lamps of -20, 24, 32 and 50 candlepower were developed for 110-volt circuits. -Lamps in various sizes from 12 to 36 cp were made for use on storage -batteries having various numbers of cells and giving a voltage of -from 20 to 40 volts. Miniature lamps of from ½ to 2 cp for use on dry -batteries of from 2½ to 5½ volts, and 3 to 6 cp on 5½ to 12 volts, were -also made. These could also be connected in series on 110 volts for -festoons. Very small lamps of ½ cp of 2 to 4 volts for use in dentistry -and surgery were made available. These miniature lamps had no bases, -wires being used to connect them to the circuit. - -[Illustration: STANDARD EDISON LAMP, 1894. - -This lamp had a “treated” cellulose filament, permitting an efficiency -of 3½ lumens per watt which has never been exceeded in a carbon -lamp. This lamp is in the exhibit of Edison lamps in the Smithsonian -Institution.] - -Lamps for 220-volt circuits were developed as this voltage was -desirable for power purposes, electric motors being used, and a few -lamps were needed on such circuits. They are less efficient and more -expensive than 110-volt lamps, their use being justified however -only when it is uneconomical to have a separate 110-volt circuit for -lighting. The lamps were made in sizes from 16 to 50 candlepower. - -[Illustration: - - Edison. Thomson-Houston. Westinghouse. Brush-Swan. - - Edi-Swan Edi-Swan United States. Hawkeye. - (single contact). (double contact). - - Ft. Wayne Jenny. Mather or Perkins. Loomis. - - Schaeffer or National. Indianapolis Jenny. Siemens & Halske. - -VARIOUS STANDARD BASES IN USE, 1892.] - -[Illustration: THOMSON-HOUSTON SOCKET.] - -[Illustration: WESTINGHOUSE SOCKET.] - -Electric street railway systems used a voltage in the neighborhood of -550, and lamps were designed to burn five in series on this voltage. -These lamps were different from the standard 110-volt lamps although -they were made for about this voltage. As they were burned in series, -the lamps were selected to operate at a definite current instead of -at a definite voltage, so that the lamps when burned in series would -operate at the proper temperature to give proper life results. Such -lamps would therefore vary considerably in individual volts, and -hence would not give good service if burned on 110-volt circuits. The -candelabra screw base and socket and the miniature screw base and -socket were later developed. Ornamental candelabra base lamps were made -for use direct on 110 volts, smaller sizes being operated in series -on this voltage. The former gave about 10 cp, the latter in various -sizes from 4 to 8 cp. The miniature screw base lamps were for low volt -lighting. - -[Illustration: - - Thomson-Houston. Westinghouse. - -ADAPTERS FOR EDISON SCREW SOCKETS, 1892. - -Next to the Edison base, the Thomson-Houston and Westinghouse bases -were the most popular. By use of these adapters, Edison base lamps -could be used in T-H and Westinghouse sockets.] - -The various manufacturers of lamps in nearly every instance made bases -that were very different from one another. No less than fourteen -different standard bases and sockets came into commercial use. -These were known as, Brush-Swan, Edison, Edi-Swan (double contact), -Edi-Swan (single contact), Fort Wayne Jenny, Hawkeye, Indianapolis -Jenny, Loomis, Mather or Perkins, Schaeffer or National, Siemens & -Halske, Thomson-Houston, United States and Westinghouse. In addition -there were later larger sized bases made for use on series circuits. -These were called the Bernstein, Heisler, Large Edison, Municipal -Bernstein, Municipal Edison, Thomson-Houston (alternating circuit) and -Thomson-Houston (arc circuit). Some of these bases disappeared from -use and in 1900 the proportion in the United States was about 70 per -cent Edison, 15 per cent Westinghouse, 10 per cent Thomson-Houston -and 5 per cent for all the others remaining. A campaign was started -to standardize the Edison base, adapters being sold at cost for the -Westinghouse and Thomson-Houston sockets so that Edison base lamps -could be used. In a few years the desired results were obtained so that -now there are no other sockets in the United States but the Edison -screw type for standard lighting service. This applies also to all -other countries in the world except England where the bayonet form of -base and socket is still popular. - -[Illustration: - - Bernstein. Heisler. Thomson-Houston - (alternating current). - - Thomson-Houston Municipal Edison. Municipal Bernstein. - (arc circuit). - -VARIOUS SERIES BASES IN USE, 1892. - -The above six bases have been superseded by the “Large Edison,” now -called the Mogul Screw base.] - - - - -THE EDISON “MUNICIPAL” STREET LIGHTING SYSTEM - - - - -[Illustration: EDISON “MUNICIPAL” SYSTEM, 1885. - - -High voltage direct current was generated, several circuits operating -in multiple, three ampere lamps burning in series on each circuit. -Photograph courtesy of Association of Edison Illuminating Companies.] - -The arc lamp could not practically be made in a unit smaller than -the so-called “1200 candlepower” (6.6 ampere) or “half” size, which -really gave about 350 spherical candlepower. A demand therefore arose -for a small street lighting unit, and Edison designed his “Municipal” -street lighting system to fill this requirement. His experience in the -making of dynamos enabled him to make a direct current bipolar constant -potential machine that would deliver 1000 volts which later was -increased to 1200 volts. They were first made in two sizes having an -output of 12 and 30 amperes respectively. Incandescent lamps were made -for 3 amperes in several sizes from 16 to 50 candlepower. These lamps -were burned in series on the 1200-volt direct current system. Thus the -12-ampere machine had a capacity for four series circuits, each taking -3 amperes, the series circuits being connected in multiple across the -1200 volts. The number of lamps on each series circuit depended upon -their size, as the voltage of each lamp was different for each size, -being about 1½ volts per cp. - -A popular size was the 32-candlepower unit, which therefore required -about 45 volts and hence at 3 amperes consumed about 135 watts. -Allowing 5 per cent loss in the wires of each circuit, there was -therefore 1140 of the 1200 volts left for the lamps. Hence about 25 -32-candlepower or 50 16-candlepower lamps could be put on each series -circuit. Different sizes of lamps could also be put on the same -circuit, the number depending upon the aggregate voltage of the lamps. - -[Illustration: EDISON MUNICIPAL LAMP, 1885. - -Inside the base was an arrangement by which the lamp was automatically -short circuited when it burned out.] - -A device was put in the base of each lamp to short circuit the lamp -when it burned out so as to prevent all the other lamps on that circuit -from going out. This device consisted of a piece of wire put inside -the lamp bulb between the two ends of the filament. Connected to this -wire was a very thin wire inside the base which held a piece of metal -compressed against a spring. The spring was connected to one terminal -of the base. Should the lamp burn out, current would jump from the -filament to the wire in the bulb, and the current then flowed through -the thin wire to the other terminal of the base. The thin wire was -melted by the current, and the spring pushed the piece of metal up -short circuiting the terminals of the base. This scheme was later -simplified by omitting the wire, spring, etc., and substituting a piece -of metal which was prevented from short circuiting the terminals of -the base by a thin piece of paper. When the lamp burned out the entire -1200 volts was impressed across this piece of paper, puncturing it and -so short circuiting the base terminals. Should one or more lamps go -out on a circuit, the increase in current above the normal 3 amperes -was prevented by an adjustable resistance, or an extra lot of lamps -which could be turned on one at a time, connected to each circuit and -located in the power station under the control of the operator. This -system disappeared from use with the advent of the constant current -transformer. - - - - -THE SHUNT BOX SYSTEM FOR SERIES INCANDESCENT LAMPS - - -[Illustration: SHUNT BOX SYSTEM, 1887. - -Lamps were burned in series on a high voltage alternating current, and -when a lamp burned out all the current then went through its “shunt -box,” a reactance coil in multiple with each lamp.] - -Soon after the commercial development of the alternating current -constant potential system, a scheme was developed to permit the use -of lamps in series on such circuits without the necessity for short -circuiting a lamp should it burn out. A reactance, called a “shunt box” -and consisting of a coil of wire wound on an iron core, was connected -across each lamp. The shunt box consumed but little current while the -lamp was burning. Should one lamp go out, the entire current would -flow through its shunt box and so maintain the current approximately -constant. It had the difficulty, however, that if several lamps went -out, the current would be materially increased tending to burn out the -remaining lamps on the circuit. This system also disappeared from use -with the development of the constant current transformer. - - - - -THE ENCLOSED ARC LAMP - - -Up to 1893 the carbons of an arc lamp operated in the open air, so -that they were rapidly consumed, lasting from eight to sixteen hours -depending on their length and thickness. Louis B. Marks, an American, -found that by placing a tight fitting globe about the arc, the life -of the carbons was increased ten to twelve times. This was due to the -restricted amount of oxygen of the air in the presence of the hot -carbon tips and thus retarded their consumption. The amount of light -was somewhat decreased, but this was more than offset by the lesser -expense of trimming which also justified the use of more expensive -better quality carbons. Satisfactory operation required that the arc -voltage be increased to about 80 volts. - -[Illustration: ENCLOSED ARC LAMP, 1893. - -Enclosing the arc lengthened the life of the carbons, thereby greatly -reducing the cost of maintenance.] - -This lamp rapidly displaced the series open arc. An enclosed arc lamp -for use on 110-volt constant potential circuits was also developed. A -resistance was put in series with the arc for use on 110-volt direct -current circuits, to act as a ballast in order to prevent the arc from -taking too much current and also to use up the difference between the -arc voltage (80) and the line voltage (110). On alternating current, a -reactance was used in place of the resistance. - -The efficiencies in lumens per watt of these arcs (with clear -glassware), all of which have now disappeared from the market, were -about as follows: - - 6.6 ampere 510 watt direct current (D.C.) series arc, 8¼ l-p-w. - 5.0 ampere 550 watt direct current multiple (110-volt) arc, 4½ l-p-w. - 7.5 ampere 540 watt alternating current (A.C.) multiple (110-volt) - arc, 4¼ l-p-w. - -[Illustration: OPEN FLAME ARC LAMP, 1898. - -Certain salts impregnated in the carbons produced a brilliantly -luminous flame in the arc stream which enormously increased the -efficiency of the lamp.] - -[Illustration: ENCLOSED FLAME ARC LAMP, 1908. - -By condensing the smoke from the arc in a cooling chamber it was -practical to enclose the flame arc, thereby increasing the life of the -carbons.] - -The reason for the big difference in efficiency between the series -and multiple direct-current arc is that in the latter a large amount -of electrical energy (watts) is lost in the ballast resistance. While -there is a considerable difference between the inherent efficiencies -of the D. C. and A. C. arcs themselves, this difference is reduced in -the multiple D. C. and A. C. arc lamps as more watts are lost in the -resistance ballast of the multiple D. C. lamp than are lost in the -reactance ballast of the multiple A. C. lamp. - -This reactance gives the A. C. lamp what is called a “power-factor.” -The product of the amperes (7.5) times the volts (110) does not give -the true wattage (540) of the lamp, so that the actual volt-amperes -(825) has to be multiplied by a power factor, in this case about 65 -per cent, to obtain the actual power (watts) consumed. The reason -is that the instantaneous varying values of the alternating current -and pressure, if multiplied and averaged throughout the complete -alternating cycle, do not equal the average amperes (measured by an -ammeter) multiplied by the average voltage (measured by a volt-meter). -That is, the maximum value of the current flowing (amperes) does not -occur at the same instant that the maximum pressure (voltage) is on the -circuit. - - - - -THE FLAME ARC LAMP - - -About 1844 Bunsen investigated the effect of introducing various -chemicals in the carbon arc. Nothing was done, however, until Bremer, -a German, experimented with various salts impregnated in the carbon -electrodes. In 1898 he produced the so-called flame arc, which -consisted of carbons impregnated with calcium fluoride. This gave a -brilliant yellow light most of which came from the arc flame, and -practically none from the carbon tips. The arc operated in the open air -and produced smoke which condensed into a white powder. - -The two carbons were inclined downward at about a 30-degree angle with -each other, and were of small diameter but long, 18 to 30 inches, -having a life of about 12 to 15 hours. The tips of the carbons -projected through an inverted earthenware cup, called the “economizer,” -the white powder condensing on this and acting not only as an excellent -reflector but making a dead air space above the arc. The arc was -maintained at the tips of the carbons by an electro-magnet whose -magnetic field “blew” the arc down. - -Two flame arc lamps were burned in series on 110-volt circuits. They -consumed 550 watts each, giving an efficiency of about 35 lumens per -watt on direct current. On alternating current the efficiency was about -30 l-p-w. By use of barium salts impregnated in the carbons, a white -light was obtained, giving an efficiency of about 18 l-p-w on direct -current and about 15½ on alternating current. These figures cover lamps -equipped with clear glassware. Using strontium salts in the carbons, -a red light was obtained at a considerably lower efficiency, such -arcs on account of their color being used only to a limited extent for -advertising purposes. - -[Illustration: CONSTANT CURRENT TRANSFORMER, 1900. - -This converted alternating current of constant voltage into constant -current, for use on series circuits.] - -These arcs were remarkably efficient but their maintenance expense was -high. Later, about 1908, enclosed flame arcs with vertical carbons were -made which increased the life of the carbons, the smoke being condensed -in cooling chambers. However, their maintenance expense was still high. -They have now disappeared from the market, having been displaced by the -very efficient gas-filled tungsten filament incandescent lamp which -appeared in 1913. - - - - -THE CONSTANT CURRENT TRANSFORMER FOR SERIES CIRCUITS - - -About 1900 the constant current transformer was developed by Elihu -Thomson. This transforms current taken from a constant potential -alternating current circuit into a constant alternating current for -series circuits, whose voltage varies with the load on the circuit. -The transformer has two separate coils; the primary being stationary -and connected to the constant potential circuit and the secondary -being movable and connected to the series circuit. The weight of the -secondary coil is slightly underbalanced by a counter weight. Current -flowing in the primary induces current in the secondary, the two coils -repelling each other. The strength of the repelling force depends -upon the amount of current flowing in the two coils. The core of the -transformer is so designed that the central part, which the two coils -surround, is magnetically more powerful close to the primary coil than -it is further away. - -When the two coils are close together a higher voltage is induced in -the secondary than if the later were further away from the primary -coil. In starting, the two coils are pulled apart by hand to prevent -too large a current flowing in the series circuit. The secondary -coil is allowed to gradually fall and will come to rest at a point -where the voltage induced in it produces the normal current in the -series circuit, the repelling force between the two coils holding the -secondary at this point. Should the load in the series circuit change -for any reason, the current in the series circuit would also change, -thus changing the force repelling the two coils. The secondary would -therefore move until the current in the series circuit again becomes -normal. The action is therefore automatic, and the actual current -in the series circuit can be adjusted within limits to the desired -amount, by varying the counterweight. A dash pot is used to prevent the -secondary coil from oscillating (pumping) too much. - -In the constant current transformer, the series circuit is insulated -from the constant potential circuit. This has many advantages. A -similar device, called an automatic regulating reactance was developed -which is slightly less expensive, but it does not have the advantage of -insulating the two circuits from each other. - - - - -ENCLOSED SERIES ALTERNATING CURRENT ARC LAMPS - - -The simplicity of the constant current transformer soon drove the -constant direct-current dynamo from the market. An enclosed arc lamp -was therefore developed for use on alternating constant current. Two -sizes of lamps were made; one for 6.6 amperes consuming 450 watts -and having an efficiency of about 4½ lumens per watt, and the other -7.5 amperes, 480 watts and 5 l-p-w (clear glassware). These lamps -soon superseded the direct current series arcs. They have now been -superseded by the more efficient magnetite arc and tungsten filament -incandescent lamps. - - - - -SERIES INCANDESCENT LAMPS ON CONSTANT CURRENT TRANSFORMERS - - -Series incandescent lamps were made for use on constant current -transformers superseding the “Municipal” and “Shunt Box” systems. The -large Edison, now called the Mogul Screw base, was adopted and the -short circuiting film cut-out was removed from the base and placed -between prongs attached to the socket. - -[Illustration: - - Holder. Socket. Holder and socket. - -SERIES INCANDESCENT LAMP SOCKET WITH FILM CUTOUT, 1900. - -The “Large Edison,” now called Mogul Screw, base was standardized and -the short circuiting device put on the socket terminals.] - -The transformers made for the two sizes of arc lamps, produced 6.6 -and 7.5 amperes and incandescent lamps, in various sizes from 16 to -50 cp, were made for these currents so that the incandescent lamps -could be operated on the same circuit with the arc lamps. The carbon -series incandescent lamp, however, was more efficient if made for lower -currents, so 3½-, 4- and 5½-ampere constant current transformers were -made for incandescent lamps designed for these amperes. Later, however, -with the advent of the tungsten filament, the 6.6-ampere series -tungsten lamp was made the standard, as it was slightly more efficient -than the lower current lamps, and was made in sizes from 32 to 400 cp. -When the more efficient gas-filled tungsten lamps were developed, the -sizes were further increased; the standard 6.6-ampere lamps now made -are from 60 to 2500 cp. - - - - -THE NERNST LAMP - - -Dr. Walther Nernst, of Germany, investigating the rare earths used in -the Welsbach mantle, developed an electric lamp having a burner, or -“glower” as it was called, consisting of a mixture of these oxides. The -main ingredient was zirconia, and the glower operated in the open air. -It is a non-conductor when cold, so had to be heated before current -would flow through it. This was accomplished by an electric heating -coil, made of platinum wire, located just above the glower. As the -glower became heated and current flowed through it, the heater was -automatically disconnected by an electro-magnet cut-out. - -[Illustration: NERNST LAMP, 1900. - -The burners consisted mainly of zirconium oxide which had to be heated -before current could go through them.] - -The resistance of the glower decreases with increase in current, so a -steadying resistance was put in series with it. This consisted of an -iron wire mounted in a bulb filled with hydrogen gas and was called -a “ballast.” Iron has the property of increasing in resistance with -increase in current flowing through it, this increase being very -marked between certain temperatures at which the ballast was operated. -The lamp was put on the American market in 1900 for use on 220-volt -alternating current circuits. The glower consumed 0.4 ampere. One, two, -three, four and six glower lamps were made, consuming 88, 196, 274, 392 -and 528 watts respectively. As most of the light is thrown downward, -their light output was generally given in mean lower hemispherical -candlepower. The multiple glower lamps were more efficient than the -single glower, owing to the heat radiated from one glower to another. -Their efficiencies, depending on the size, were from about 3½ to 5 -lumens per watt, and their average candlepower throughout life was -about 80 per cent of initial. The lamp disappeared from the market -about 1912. - -[Illustration: DIAGRAM OF NERNST LAMP.] - - - - -THE COOPER-HEWITT LAMP - - -In 1860 Way discovered that if an electric circuit was opened between -mercury contacts a brilliant greenish colored arc was produced. -Mercury was an expensive metal and as the carbon arc seemed to give -the most desirable results, nothing further was done for many years -until Dr. Peter Cooper Hewitt, an American, began experimenting with -it. He finally produced an arc in vacuum in a one-inch glass tube -about 50 inches long for 110 volts direct current circuits, which was -commercialized in 1901. The tube hangs at about 15 degrees from the -horizontal. The lower end contains a small quantity of mercury. The -terminals are at each end of the tube, and the arc was first started -by tilting the tube by hand so that a thin stream of mercury bridged -the two terminals. Current immediately vaporized the mercury, starting -the arc. A resistance is put in series with the arc to maintain the -current constant on direct current constant voltage circuits. Automatic -starting devices were later developed, one of which consisted of an -electro-magnet that tilted the lamp, and the other of an induction coil -giving a high voltage which, in discharging, started the arc. - -[Illustration: COOPER-HEWITT MERCURY VAPOR ARC LAMP, 1901. - -This gives a very efficient light, practically devoid of red but of -high actinic value, so useful in photography.] - -This lamp is particularly useful in photography on account of the -high actinic value of its light. Its light is very diffused and is -practically devoid of red rays, so that red objects appear black in its -light. The lamp consumes 3½ amperes at 110 volts direct current (385 -watts) having an efficiency of about 12½ lumens per watt. - -The mercury arc is peculiar in that it acts as an electric valve -tending to let current flow through it only in one direction. Thus -on alternating current, the current impulses will readily go through -it in one direction, but the arc will go out in the other half cycle -unless means are taken to prevent this. This is accomplished by having -two terminals at one end of the tube, which are connected to choke -coils, which in turn are connected to a single coil (auto) transformer. -The alternating current supply mains are connected to wires tapping -different parts of the coil of the auto transformer. The center of -the coil of the auto transformer is connected through an induction -coil to the other end of the tube. By this means the alternating -current impulses are sent through the tube in one direction, one half -cycle from one of the pairs of terminals of the tube, the other half -cycle from the other terminal. Thus pulsating direct current, kept -constant by the induction coil, flows through the tube, the pulsations -overlapping each other by the magnetic action of the choke coils. This -alternating current lamp is started by the high voltage discharge -method. It has a 50-inch length of tube, consuming about 400 watts on -110 volts. Its efficiency is a little less than that of the direct -current lamp. - -[Illustration: DIAGRAM OF COOPER-HEWITT LAMP FOR USE ON ALTERNATING -CURRENT. - -The mercury arc is inherently for use on direct current, but by means -of reactance coils, it can be operated on alternating current.] - - - - -THE LUMINOUS OR MAGNETITE ARC LAMP - - -About 1901 Dr. Charles P. Steinmetz, Schenectady, N. Y., studied the -effect of metallic salts in the arc flame. Dr. Willis R. Whitney, -also of Schenectady, and director of the research laboratory of the -organization of which Dr. Steinmetz is the consulting engineer, -followed with some further work along this line. The results of this -work were incorporated in a commercial lamp called the magnetite arc -lamp, through the efforts of C. A. B. Halvorson, Jr., at Lynn, Mass. -The negative electrode consists of a pulverized mixture of magnetite -(a variety of iron ore) and other substances packed tightly in an iron -tube. The positive electrode is a piece of copper sheathed in iron to -prevent oxidization of the copper. The arc flame gives a brilliant -white light, and, similar to the mercury arc, is inherently limited to -direct current. It burns in the open air at about 75 volts. The lamp is -made for 4-ampere direct current series circuits and consumes about 310 -watts and has an efficiency of about 11½ lumens per watt. - -[Illustration: LUMINOUS OR MAGNETITE ARC LAMP, 1902. - -This has a negative electrode containing magnetite which produces a -very luminous white flame in the arc stream.] - -The negative (iron tube) electrode now has a life of about 350 hours. -Later, a higher efficiency, 4-ampere electrode was made which has -a shorter life but gives an efficiency of about 17 l-p-w, and a -6.6-ampere lamp was also made giving an efficiency of about 18 l-p-w -using the regular electrode. This electrode in being consumed gives -off fumes, so the lamp has a chimney through its body to carry them -off. Some of the fumes condense, leaving a fine powder, iron oxide, in -the form of rust. The consumption of the positive (copper) electrode -is very slow, which is opposite to that of carbon arc lamps on direct -current. The arc flame is brightest near the negative (iron tube) -electrode and decreases in brilliancy and volume as it nears the -positive (copper) electrode. - -[Illustration: DIAGRAM OF SERIES MAGNETITE ARC LAMP. - -The method of control, entirely different from that of other arc lamps, -was invented by Halvorson to meet the peculiarities of this arc.] - -The peculiarities of the arc are such that Halvorson invented an -entirely new principle of control. The electrodes are normally apart. -In starting, they are drawn together by a starting magnet with -sufficient force to dislodge the slag which forms on the negative -electrode and which becomes an insulator when cold. Current then flows -through the electrodes and through a series magnet which pulls up a -solenoid breaking the circuit through the starting magnet. This allows -the lower electrode to fall a fixed distance, about seven-eighths of -an inch, drawing the arc, whose voltage is then about 72 volts. As the -negative electrode is consumed, the length and voltage of the arc -increases when a magnet, in shunt with the arc, becomes sufficiently -energized to close the contacts in the circuit of the starting magnet -causing the electrode to pick up and start off again. - - - - -MERCURY ARC RECTIFIER FOR MAGNETITE ARC LAMPS - - -[Illustration: MERCURY ARC RECTIFIER TUBE FOR SERIES MAGNETITE ARC -LAMPS, 1902. - -The mercury arc converted the alternating constant current into direct -current required by the magnetite lamp.] - -As the magnetite arc requires direct current for its operation, the -obvious way to supply a direct constant current for series circuits -is to rectify, by means of the mercury arc, the alternating current -obtained from a constant current transformer. The terminals of the -movable secondary coil of the constant current transformer are -connected to the two arms of the rectifier tube. One end of the series -circuit is connected to the center of the secondary coil. The other -end of the series circuit is connected to a reactance which in turn -is connected to the pool of mercury in the bottom of the rectifier -tube. One-half of the cycle of the alternating current goes from the -secondary coil to one arm of the rectifier tube through the mercury -vapor, the mercury arc having already been started by a separate -starting electrode. It then goes to the pool of mercury, through -the reactance and through the series circuit. The other half cycle -of alternating current goes to the other arm of the rectifier tube, -through the mercury vapor, etc., and through the series circuit. Thus a -pulsating direct current flows through the series circuit, the magnetic -action of the reactance coil making the pulsations of current overlap -each other, which prevents the mercury arc from going out. - -[Illustration: EARLY MERCURY ARC RECTIFIER INSTALLATION.] - - - - -INCANDESCENT LAMP DEVELOPMENTS, 1894–1904 - - -With the development of a waterproof base in 1900, by the use of a -waterproof cement instead of plaster of Paris to fasten the base to -the bulb, porcelain at first and later glass being used to insulate -the terminals of the base from each other, lamps could be exposed to -the weather and give good results. Electric sign lighting therefore -received a great stimulus, and lamps as low as 2 candlepower for 110 -volts were designed for this purpose. Carbon lamps with concentrated -filaments were also made for stereoptican and other focussing purposes. -These lamps were made in sizes from 20 to 100 candlepower. The arc lamp -was more desirable for larger units. - -The dry battery was made in small units of 2, 3 and 5 cells, so that -lamps of about ⅛ to 1 candlepower were made for 2½, 3½ and 6½ volts, -for portable flashlights. It was not however until the tungsten -filament was developed in 1907 that these flashlights became as popular -as they now are. For ornamental lighting, lamps were supplied in round -and tubular bulbs, usually frosted to soften the light. - -[Illustration: THE MOORE TUBE LIGHT, 1904. - -This consisted of a tube about 1¾ inches in diameter and having a -length up to 200 feet, in which air at about one thousandth part -of atmospheric pressure was made to glow by a very high voltage -alternating current.] - - - - -THE MOORE TUBE LIGHT - - -Geissler, a German, discovered sixty odd years ago, that a high voltage -alternating current would cause a vacuum tube to glow. This light -was similar to that obtained by Hawksbee over two hundred years ago. -Geissler obtained his high voltage alternating current by a spark -coil, which consisted of two coils of wire mounted on an iron core. -Current from a primary battery passed through the primary coil, and -this current was rapidly interrupted by a vibrator on the principle of -an electric bell. This induced an alternating current of high voltage -in the secondary coil as this coil had a great many more turns than -the primary coil had. Scientists found that about 70 per cent of the -electrical energy put into the Geissler tube was converted into the -actual energy in the light given out. - -In 1891 Mr. D. McFarlan Moore, an American, impressed with the fact -that only one-half of one per cent of the electrical energy put into -the carbon-incandescent lamp came out in the form of light, decided to -investigate the possibilities of the vacuum tube. After several years -of experiments and the making of many trial lamps, he finally, in 1904, -made a lamp that was commercially used in considerable numbers. - -[Illustration: DIAGRAM OF FEEDER VALVE OF MOORE TUBE. - -As the carbon terminals inside the tube absorbed the very slight -amount of gas in the tube, a feeder valve allowed gas to flow in the -tube, regulating the pressure to within one ten thousandth part of -an atmosphere above and below the normal extremely slight pressure -required.] - -The first installation of this form of lamp was in a hardware store -in Newark, N. J. It consisted of a glass tube 1¾ inches in diameter -and 180 feet long. Air, at a pressure of about one-thousand part of -an atmosphere, was in the tube, from which was obtained a pale pink -color. High voltage (about 16,000 volts) alternating current was -supplied by a transformer to two carbon electrodes inside the ends of -the tube. The air had to be maintained within one ten-thousandth part -of atmospheric pressure above and below the normal of one-thousandth, -and as the rarefied air in the tube combined chemically with the carbon -electrodes, means had to be devised to maintain the air in the tube at -this slight pressure as well as within the narrow limits required. - -This was accomplished by a piece of carbon through which the air could -seep, but if covered with mercury would make a tight seal. As the air -pressure became low, an increased current would flow through the tube, -the normal being about a tenth of an ampere. This accordingly increased -the current flowing through the primary coil of the transformer. In -series with the primary coil was an electro-magnet which lifted, as the -current increased, a bundle of iron wires mounted in a glass tube which -floated in mercury. The glass tube, rising, lowered the height of the -mercury, uncovering a carbon rod cemented in a tube connecting the main -tube with the open air. Thus air could seep through this carbon rod -until the proper amount was fed into the main tube. When the current -came back to normal the electro-magnet lowered the floating glass tube -which raised the height of the mercury and covered the carbon rod, thus -shutting off the further supply of air. - -As there was a constant loss of about 400 watts in the transformer, -and an additional loss of about 250 watts in the two electrodes, the -total consumption of the 180-foot tube was about 2250 watts. Nitrogen -gas gave a yellow light, which was more efficient and so was later -used. On account of the fixed losses in the transformer and electrodes -the longer tubes were more efficient, though they were made in various -sizes of from 40 to 200 feet. The 200-foot tube, with nitrogen, had an -efficiency of about 10 lumens per watt. Nitrogen gas was supplied to the -tube by removing the oxygen from the air used. This was accomplished by -passing the air over phosphorous which absorbed the oxygen. - -Carbon dioxide gas (CO_{2}) gave a pure white light but at about -half the efficiency of nitrogen. The gas was obtained by allowing -hydrochloric acid to come in contact with lumps of marble (calcium -carbonate) which set free carbon dioxide and water vapor. The latter -was absorbed by passing the gas through lumps of calcium chloride. The -carbon dioxide tube on account of its daylight color value, made an -excellent light under which accurate color matching could be done. A -short tube is made for this purpose and this is the only use which the -Moore tube now has, owing to the more efficient and simpler tungsten -filament incandescent lamp. - - - - -THE OSMIUM LAMP - - -Dr. Auer von Welsbach, the German scientist who had produced the -Welsbach gas mantle, invented an incandescent electric lamp having a -filament of the metal osmium. It was commercially introduced in Europe -in 1905 and a few were sold, but it was never marketed in this country. -It was generally made for 55 volts, two lamps to burn in series on -110-volt circuits, gave about 25 candlepower and had an initial -efficiency of about 5½ lumens per watt. It had a very fair maintenance -of candlepower during its life, having an average efficiency of about -5 l-p-w. Osmium is a very rare and expensive metal, usually found -associated with platinum, and is therefore very difficult to obtain. -Burnt out lamps were therefore bought back in order to obtain a supply -of osmium. It is also a very brittle metal, so that the lamps were -extremely fragile. - -[Illustration: OSMIUM LAMP, 1905. - -This incandescent lamp was used in Europe for a few years, but was -impractical to manufacture in large quantities as osmium is rarer and -more expensive than platinum.] - - - - -THE GEM LAMP - - -Dr. Willis R. Whitney, of Schenectady, N. Y., had invented an -electrical resistance furnace. This consisted of a hollow carbon tube, -packed in sand, through which a very heavy current could be passed. -This heated the tube to a very high temperature, the sand preventing -the tube from oxidizing, so that whatever was put inside the tube -could be heated to a very high heat. Among his various experiments, -he heated some carbon filaments and found that the high temperature -changed their resistance “characteristic” from negative to positive. -The ordinary carbon filament has a resistance when hot that is less -than when it is cold, which was reversed after heating it to the high -temperature Dr. Whitney was able to obtain. These filaments were made -into lamps for 110-volt service and it was found that they could -be operated at an efficiency of 4 lumens per watt. The lamps also -blackened less than the regular carbon lamp throughout their life. - -[Illustration: GEM LAMP, 1905. - -This incandescent lamp had a graphitized carbon filament obtained by -the heat of an electric furnace, so that it could be operated at 25 per -cent higher efficiency than the regular carbon lamp. This lamp is in -the exhibit of Edison lamps in the Smithsonian Institution.] - -This lamp was put on the market in 1905 and was called the Gem or -metallized carbon filament lamp as such a carbon filament had a -resistance characteristic similar to metals. At first it had two single -hair pin filaments in series which in 1909 were changed to a single -loop filament like the carbon lamp. - -In 1905 the rating of incandescent lamps was changed from a candlepower -to a wattage basis. The ordinary 16-candlepower carbon lamp consumed -50 watts and was so rated. The 50-watt Gem lamp gave 20 candlepower, -both candlepower ratings being their mean candlepower in a horizontal -direction. The Gem lamp was made for 110-volt circuits in sizes from -40 to 250 watts. The 50-watt size was the most popular, many millions -of which were made before the lamp disappeared from use in 1918. The -lamp was not quite as strong as the carbon lamp. Some Gem lamps for -series circuits were also made, but these were soon superseded by the -tungsten-filament lamp which appeared in 1907. - - - - -THE TANTALUM LAMP - - -[Illustration: TANTALUM LAMP, 1906. - -The tantalum filament could be operated at 50 per cent greater -efficiency than that of the regular carbon incandescent lamp. This lamp -is in the exhibit of Edison lamps in the Smithsonian Institution.] - -Dr. Werner von Bolton, a German physicist, made an investigation of -various materials to see if any of them were more suitable than carbon -for an incandescent-lamp filament. After experimenting with various -metals, tantalum was tried. Tantalum had been known to science for -about a hundred years. Von Bolton finally obtained some of the pure -metal and found it to be ductile so that it could be drawn out into a -wire. As it had a low specific resistance, the wire filament had to -be much longer and thinner than the carbon filament. A great number -of experimental lamps were made so that it was not until 1906 that -the lamp was put on the market in this country. It had an initial -efficiency of 5 lumens per watt and a good maintenance of candle power -throughout its life, having an average efficiency of about 4¼ l-p-w. -The usual sizes of lamps were 40 and 80 watts giving about 20 and 40 -candlepower respectively. It was not quite as strong as the carbon -lamp, and on alternating current the wire crystallized more rapidly, -so that it broke more easily, giving a shorter life than on direct -current. It disappeared from use in 1913. - - - - -INVENTION OF THE TUNGSTEN LAMP - - -Alexander Just and Franz Hanaman in 1902 were laboratory assistants -to the Professor of Chemistry in the Technical High School in Vienna. -Just was spending his spare time in another laboratory in Vienna, -attempting to develop a boron incandescent lamp. In August of that year -he engaged Hanaman to aid him in his work. They conceived the idea of -making a lamp with a filament of tungsten and for two years worked on -both lamps. The boron lamp turned out to be a failure. Their means -were limited; Hanaman’s total income was $44 per month and Just’s was -slightly more than this. In 1903 they took out a German patent on a -tungsten filament, but the process they described was a failure because -it produced a filament containing both carbon and tungsten. The carbon -readily evaporated and quickly blackened the bulb when they attempted -to operate the filament at an efficiency higher than that possible with -the ordinary carbon filament. Finally in the latter part of the next -year (1904) they were able to get rid of the carbon and produced a pure -tungsten filament. - -Tungsten had been known to chemists for many years by its compounds, -its oxides and its alloys with steel, but the properties of the pure -metal were practically unknown. It is an extremely hard and brittle -metal and it was impossible at that time to draw it into a wire. Just -and Hanaman’s process of making a pure tungsten filament consisted of -taking tungsten oxide in the form of an extremely fine powder, reducing -this to pure tungsten powder by heating it while hydrogen gas passed -over it. The gas combined with the oxygen of the oxide, forming water -vapor which was carried off, leaving the tungsten behind. - -The tungsten powder was mixed with an organic binding material, and -the paste was forced by very high pressure through a hole drilled in -a diamond. This diamond die was necessary because tungsten, being so -hard a substance, would quickly wear away any other kind of die. The -thread formed was cut into proper lengths, bent the shape of a hair -pin and the ends fastened to clamps. Current was passed through the -hair pin in the presence of hydrogen gas and water vapor. The current -heated the hair pin, carbonized the organic binding material in it, the -carbon then combining with the moist hydrogen gas, leaving the tungsten -particles behind. These particles were sintered together by the heat, -forming the tungsten filament. Patents were applied for in various -countries, the one in the United States on July 6, 1905. - -The two laboratory assistants in 1905 finally succeeded in getting -their invention taken up by a Hungarian lamp manufacturer. By the end -of the year lamps were made that were a striking success for they could -be operated at an efficiency of 8 lumens per watt. They were put on -the American market in 1907, the first lamp put out being the 100-watt -size for 110-volt circuits. This was done by mounting several hair pin -loops in series to get the requisite resistance, tungsten having a -low specific resistance. The issue of the American patent was delayed -owing to an interference between four different parties, each claiming -to be the inventor. After prolonged hearings, one application having -been found to be fraudulent, the patent was finally granted to Just and -Hanaman on February 27, 1912. - -[Illustration: TUNGSTEN LAMP, 1907. - -The original 100 watt tungsten lamp was nearly three times as efficient -as the carbon lamp, but its “pressed” filament was very fragile. This -lamp is in the exhibit of Edison lamps in the Smithsonian Institution.] - -This “pressed” tungsten filament was quite fragile, but on account of -its relatively high efficiency compared with other incandescent lamps, -it immediately became popular. Soon after its introduction it became -possible to make finer filaments so that lamps for 60, 40 and then 25 -watts for 110-volt circuits were made available. Sizes up to 500 watts -were also made which soon began to displace the enclosed carbon arc -lamp. Lamps were also made for series circuits in sizes from 32 to 400 -candlepower. These promptly displaced the carbon and Gem series lamps. -The high efficiency of the tungsten filament was a great stimulus to -flashlights which are now sold by the millions each year. The lighting -of railroad cars, Pullmans and coaches, with tungsten lamps obtaining -their current from storage batteries, soon superseded the gas light -formerly used. In some cases, a dynamo, run by a belt from the car -axle, kept these batteries charged. - -[Illustration: DRAWN TUNGSTEN WIRE LAMP, 1911. - -Scientists had declared it impossible to change tungsten from a brittle -to ductile metal. This, however, was accomplished by Dr. Coolidge, and -drawn tungsten wire made the lamp very sturdy. This lamp is in the -exhibit of Edison lamps in the Smithsonian Institution.] - - - - -DRAWN TUNGSTEN WIRE - - -After several years of patient experiment, Dr. William D. Coolidge -in the research laboratory of a large electrical manufacturing -company at Schenectady, N. Y., invented a process for making tungsten -ductile, a patent for which was obtained in December, 1913. Tungsten -had heretofore been known as a very brittle metal, but by means of -this process it became possible to draw it into wire. This greatly -simplified the manufacture of lamps and enormously improved their -strength. Such lamps were commercially introduced in 1911. - -With drawn tungsten wire it was easier to coil and therefore -concentrate the filament as required by focusing types of lamps. The -automobile headlight lamp was among the first of these, which in 1912 -started the commercial use of electric light on cars in place of oil -and acetylene gas. On street railway cars the use of tungsten lamps, -made possible on this severe service by the greater sturdiness of -the drawn wire, greatly improved their lighting. Furthermore, as the -voltage on street railway systems is subject to great changes, the -candlepower of the tungsten filament has the advantage of varying but -about half as much as that of the carbon lamp on fluctuating voltage. - -[Illustration: QUARTZ MERCURY VAPOR LAMP, 1912. - -The mercury arc if enclosed in quartz glass can be operated at much -higher temperature and therefore greater efficiency. The light is -still deficient in red but gives a considerable amount of ultra-violet -rays which kill bacteria and are very dangerous to the eye. They can, -however, be absorbed by a glass globe. The lamp is not used as an -illuminant in this country, but is valuable for use in the purification -of water.] - - - - -THE QUARTZ MERCURY VAPOR ARC LAMP - - -By putting a mercury arc in a tube made of quartz instead of glass, -it can be operated at a much higher temperature and thereby obtain a -greater efficiency. Such a lamp, however, is still largely deficient in -red rays, and it gives out a considerable amount of ultra-violet rays. -These ultra-violet rays will kill bacteria and the lamp is being used -to a certain extent for such purpose as in the purification of water. -These rays are very dangerous to the eyes, but they are absorbed by -glass, so as an illuminant, a glass globe must be used on the lamp. -These lamps appeared in Europe about 1912 but were never used to any -extent in this country as an illuminant. They have an efficiency of -about 26 lumens per watt. Quartz is very difficult to work, so the cost -of a quartz tube is very great. The ordinary bunsen gas flame is used -with glass, but quartz will only become soft in an oxy-hydrogen or -oxy-acetylene flame. - -[Illustration: GAS FILLED TUNGSTEN LAMP, 1913. - -By operating a coiled filament in an inert gas, Dr. Langmuir was able -to greatly increase its efficiency, the gain in light by the higher -temperature permissible, more than offsetting the loss of heat by -convection of the gas. This lamp is in the exhibit of Edison lamps in -the Smithsonian Institution.] - - - - -THE GAS-FILLED TUNGSTEN LAMP - - -The higher the temperature at which an incandescent lamp filament can -be operated, the more efficient it becomes. The limit in temperature is -reached when the material begins to evaporate rapidly, which blackens -the bulb. The filament becoming thinner more quickly, thus rupturing -sooner, shortens the life. If, therefore, the evaporating temperature -can by some means be slightly raised, the efficiency will be greatly -improved. This was accomplished by Dr. Irving Langmuir in the research -laboratories at Schenectady, N. Y., by operating a tungsten filament -in an inert gas. Nitrogen was first used. The gas circulating in the -bulb has the disadvantage of conducting heat away from the filament -so that the filament was coiled. This presented a smaller surface to -the currents of gas and thereby reduced this loss. The lamps were -commercially introduced in 1913 and a patent was granted in April, 1916. - -[Illustration: GAS FILLED TUNGSTEN LAMP, 1923. - -This is the form of the lamp as at present made. For 110-volt circuits -the sizes range from 50 to 1000 watts.] - -An increased amount of electrical energy is required in these lamps -to offset the heat being conducted away by the gas. This heat loss is -minimized in a vacuum lamp, the filament tending to stay hot on the -principle of the vacuum bottle. This loss in a gas filled lamp becomes -relatively great in a filament of small diameter, as the surface in -proportion to the volume of the filament increases with decreasing -diameters. Hence there is a point where the gain in temperature is -offset by the heat loss. The first lamps made were of 750 and 1000 -watts for 110-volt circuits. Later 500- and then 400-watt lamps were -made. The use of argon gas, which has a poorer heat conductivity than -nitrogen, made it possible to produce smaller lamps, 50-watt gas-filled -lamps for 110-volt circuits now being the smallest available. In the -present state of the art, a vacuum lamp is more efficient than a -gas-filled lamp having a filament smaller than one consuming about half -an ampere. Thus gas-filled lamps are not now practicable much below 100 -watts for 220 volts, 50 watts for 110 volts, 25 watts for 60 volts, 15 -watts for 30 volts, etc. - -From the foregoing it will be seen that the efficiency of these lamps -depends largely on the diameter of the filament. There are other -considerations, which also apply to vacuum lamps, that affect the -efficiency. Some of these are: the number of anchors used, as they -conduct heat away; in very low voltage lamps having short filaments the -relative amount of heat conducted away by the leading-in wires becomes -of increasing importance, etc. The 1000-watt lamp for 110-volt circuits -is now made for nearly 20½ lumens per watt; the 50-watt lamp a little -over 10 l-p-w. - -The advent of the tungsten filament and especially the gas-filled -lamp sounded the doom of all other electric illuminants except the -magnetite and mercury arc lamps. All other incandescent lamps have now -practically disappeared. The flame arc as well as the enclosed carbon -arc lamp are hardly ever seen. The simplicity of the incandescent -lamp, its cleanliness, low first cost, low maintenance cost and high -efficiency of the tungsten filament have been the main reasons for its -popularity. - - - - -TYPES AND SIZES OF TUNGSTEN LAMPS NOW MADE - - -There are about two hundred different types and sizes of tungsten -filament lamps now standard for various kinds of lighting service. For -110-volt service, lamps are made in sizes from 10 to 1000 watts. Of -the smaller sizes, some are made in round and tubular-shaped bulbs for -ornamental lighting. In addition there are the candelabra lamps used -in ornamental fixtures. Twenty-five- to five hundred-watt lamps are -made with bulbs of special blue glass to cut out the excess of red and -yellow rays and thus produce a light approximating daylight. - -For 220-volt service lamps are made in sizes of from 25 to 1000 watts. -For sign lighting service, 5-watt lamps of low voltage are made for -use on a transformer located near the sign to reduce the 110 volts -alternating current to that required by the lamps. Lamps are made from -5 to 100 watts for 30-volt service, such as is found in train lighting -and in gas engine driven dynamo sets used in rural homes beyond the -reach of central station systems. Concentrated filament lamps are -made for stereopticon and motion picture projection, floodlighting, -etc., in sizes from 100 to 1000 watts, for street railway headlights -in sizes below 100 watts and for locomotive headlights in sizes from -100 to 250 watts. For series circuits, used in street lighting, lamps -are made from 60 to 2500 candlepower. Miniature lamps cover those for -flashlight, automobile, Christmas-tree, surgical and dental services, -etc. They range, depending on the service, from ½ to 21 candlepower, -and in voltage from 2½ to 24. - -[Illustration: STANDARD TUNGSTEN LAMPS, 1923. - -This illustrates some of the two hundred different lamps regularly -made.] - - - - -STANDARD VOLTAGES - - -Mention has been made of 110-volt service, 220-volt service, etc. -In the days of the carbon incandescent lamp it was impossible to -manufacture all lamps for an exact predetermined voltage. The popular -voltage was 110, so lighting companies were requested in a number of -instances to adjust their service to some voltage other than 110. They -were thus able to utilize the odd voltage lamps manufactured, and this -produced a demand for lamps of various voltages from 100 to 130. Arc -lamps had a resistance (reactance on alternating current) that was -adjustable for voltages between 100 and 130. - -Similarly a demand was created for lamps of individual voltages of -from 200 to 260. The 200- to 260-volt range has simmered down to -220, 230, 240 and 250 volts. These lamps are not as efficient as the -110-volt type and their demand is considerably less, as the 110-volt -class of service for lighting is, with the exception of England, -almost universal. Thus 110-volt service means 100 to 130 volts in -contra-distinction to 200 to 260 volts, etc. The drawn tungsten wire -filament made it possible to accurately predetermine the voltage of -the lamp, so now that the carbon incandescent lamp is a thing of the -past, there is no need for so many different voltages. Several years -ago standard voltages of 110, 115 and 120 were recommended for adoption -by all the electrical societies in the United States, and practically -all central stations have now changed their service to one of these -voltages. - - - - -COST OF INCANDESCENT ELECTRIC LIGHT - - -In the early ’80’s current was expensive, costing a consumer on the -average about twenty cents per kilowatt hour. The cost has gradually -come down and the general average rate for which current is sold for -lighting purposes is now about 4½ cents. During the period 1880 to 1905 -the average efficiency of carbon lamps throughout their life increased -from about one to over 2¾ lumens per watt and their list price -decreased from one dollar to twenty cents. The average amount of light -obtained for one cent at first was about five candlepower hours and in -1904 it was increased to over thirty-six at the average rate then in -effect. The next year with the more efficient Gem lamp 44 candle-hours -could be had for one cent. In 1906 the amount was increased to 50 with -the tantalum lamp and with the tungsten lamp in 1907, even at its high -price of $1.50, the amount was further increased to 63. Since then -the average cost of current has been reduced but slightly, but the -efficiency of the tungsten lamp has materially increased and its cost -reduced so that it is now possible to obtain, with the ordinary 40-watt -lamp 170 candle-hours for a cent. If the gas-filled tungsten lamp were -used the amount of light now obtained for a cent would depend upon the -size, which, for the 1000-watt lamp, would be 382 candle-hours. - - - - -STATISTICS REGARDING THE PRESENT DEMAND FOR LAMPS - - -In the United States there are about 350 million incandescent and -about two hundred thousand magnetite arc lamps now (1923) in use. -They are increasing about 10 per cent each year. The annual demand -for incandescent lamps for renewals and new installations is over 200 -millions, exclusive of miniature lamps. The use of incandescent lamps -in all other countries put together is about equal that in the U. S. - -The average candlepower of standard lighting lamps has increased from -16, which prevailed during the period prior to 1905, to over 60. The -average wattage has not varied much during the past twenty-odd years, -the average lamp now consuming about 55 watts. This indicates that the -public is utilizing the improvement in lamp efficiency by increased -illumination. The present most popular lamp is the 40-watt size which -represents 20 per cent of the total demand. Second in demand is the -25-watt at 18 per cent and third, the 50-watt at 15 per cent of the -total in numbers. While the aggregate demand of all the gas-filled -tungsten lamps is a little over 20 per cent in numbers, they represent, -on account of their greater efficiency and wattage, over half the -amount of total candlepower used. In the United States about 85 per -cent of all lamps are for the 110-volt range. About 5 per cent for 220 -volts, 2 per cent for street series lighting, 3 per cent for street -railway and 5 per cent for trainlighting and miscellaneous classes of -service. - - - - -SELECTED BIBLIOGRAPHY - - - ALGLAVE AND BOULARD, “The Electric Light,” translated by T. - O’Connor Sloane, edited by C. M. Lungren, D. Appleton & Co., - New York, 1884. - - BARHAM, G. BASIL, “The Development of the Incandescent Electric - Lamp,” Scott Greenwood & Son, London, 1912. - - DREDGE, JAMES, “Electric Illumination,” 2 vols., John Wiley & Sons, - New York, 1882. - - DURGIN, WILLIAM A., “Electricity--Its History and Development,” - A. C. McClurg & Co., Chicago, 1912. - - DYER & MARTIN, “Edison, His Life and Inventions,” 2 vols., Harper & - Bros., New York, 1910. - - GUILLEMIN, AMEDEE, “Electricity and Magnetism,” edited by Silvanus - P. Thompson, McMillan & Co., London, 1891. - - HOUSTON, EDWIN J., “Electricity One Hundred Years ago and To-day,” - The W. J. Johnston Co., New York, 1894. - - HOUSTON AND KENNELLY, “Electric Arc Lighting,” McGraw Publishing - Co., New York, 1906. - - HUTCHINSON, ROLLIN W., JR., “High Efficiency Electrical Illuminants - and Illumination,” John Wiley & Sons, New York, 1911. - - MAIER, JULIUS, “Arc and Glow Lamps,” Whittaker & Co., London, 1886. - - POPE, FRANKLIN LEONARD, “Evolution of the Electric Incandescent - Lamp,” Boschen & Wefer, New York, 1894. - - SOLOMON, MAURICE, “Electric Lamps,” D. Van Nostrand Co., New York, - 1908. - - - - -Transcriber’s Notes - - -Punctuation, hyphenation, and spelling were made consistent when a -predominant preference was found in the original book; otherwise they -were not changed. - -Simple typographical errors were corrected; unbalanced quotation -marks were remedied when the change was obvious, and otherwise left -unbalanced. - -Illustrations in this eBook have been positioned between paragraphs. 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margin:1em 0'> -This eBook is for the use of anyone anywhere in the United States and -most other parts of the world 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 <a href="https://www.gutenberg.org">www.gutenberg.org</a>. If you -are not located in the United States, you will have to check the laws of the -country where you are located before using this eBook. -</div> - -<p style='display:block; margin-top:1em; margin-bottom:1em; margin-left:2em; text-indent:-2em'>Title: History of electric light</p> -<p style='display:block; margin-top:1em; margin-bottom:0; margin-left:2em; text-indent:-2em'>Author: Henry Schroeder</p> -<p style='display:block; text-indent:0; margin:1em 0'>Release Date: June 16, 2022 [eBook #68326]</p> -<p style='display:block; text-indent:0; margin:1em 0'>Language: English</p> - <p style='display:block; margin-top:1em; margin-bottom:0; margin-left:2em; text-indent:-2em; text-align:left'>Produced by: Charlene Taylor, Charlie Howard, and the Online Distributed Proofreading Team at https://www.pgdp.net (This file was produced from images generously made available by The Internet Archive/American Libraries.)</p> -<div style='margin-top:2em; margin-bottom:4em'>*** START OF THE PROJECT GUTENBERG EBOOK HISTORY OF ELECTRIC LIGHT ***</div> - -<div class="transnote"> -<p class="center larger">Transcriber’s Note</p> - -<p>Larger versions of most illustrations may be seen by right-clicking them -and selecting an option to view them separately, or by double-tapping and/or -stretching them.</p> - -<p class="covernote">Cover image created by Transcriber, using illustrations -from the original book, and placed into the Public Domain.</p> -</div> - -<p class="newpage p2 center wspace"> -SMITHSONIAN MISCELLANEOUS COLLECTIONS<br /> -<span class="smaller">VOLUME 76, NUMBER 2</span></p> - -<h1>HISTORY OF ELECTRIC LIGHT</h1> - -<p class="p2 center">BY<br /> -HENRY SCHROEDER<br /> -<span class="smaller">Harrison, New Jersey</span></p> - -<div class="figcenter"> - <img src="images/i_000.png" width="621" height="615" style="width: 20%;" alt="" /> - <div class="caption"><p>FOR THE INCREASE<br /> -AND DIFFVSION OF<br /> -KNOWLEDGE AMONG MEN</p> - -<p>SMITHSONIAN<br /> -INSTITVTION<br /> -WASHINGTON 1846</p></div></div> - -<p class="center smaller">(<span class="smcap">Publication 2717</span>)</p> - -<p class="p2 center smaller">CITY OF WASHINGTON<br /> -PUBLISHED BY THE SMITHSONIAN INSTITUTION<br /> -AUGUST 15, 1923 -</p> - -<hr class="chap x-ebookmaker-drop" /> - -<p class="newpage p4 center smaller"> -<span class="bold">The Lord Baltimore Press</span><br /> -<span class="smaller">BALTIMORE, MD., U. S. A.</span> -</p> - -<hr class="chap x-ebookmaker-drop" /> - -<div class="chapter"> -<p><span class="pagenum" id="Page_iii">iii</span></p> - -<h2 class="nobreak" id="CONTENTS">CONTENTS</h2> -</div> - -<table id="toc"> -<tr class="small"> - <td> </td> - <td class="tdr">PAGE</td> -</tr> -<tr> - <td class="tdl">List of Illustrations</td> - <td class="tdr"><a href="#chap_1">v</a></td> -</tr> -<tr> - <td class="tdl">Foreword</td> - <td class="tdr"><a href="#chap_2">ix</a></td> -</tr> -<tr> - <td class="tdl">Chronology of Electric Light</td> - <td class="tdr"><a href="#chap_3">xi</a></td> -</tr> -<tr> - <td class="tdl">Early Records of Electricity and Magnetism</td> - <td class="tdr"><a href="#chap_4">1</a></td> -</tr> -<tr> - <td class="tdl">Machines Generating Electricity by Friction</td> - <td class="tdr"><a href="#chap_5">2</a></td> -</tr> -<tr> - <td class="tdl">The Leyden Jar</td> - <td class="tdr"><a href="#chap_6">3</a></td> -</tr> -<tr> - <td class="tdl">Electricity Generated by Chemical Means</td> - <td class="tdr"><a href="#chap_7">3</a></td> -</tr> -<tr> - <td class="tdl">Improvement of Volta’s Battery</td> - <td class="tdr"><a href="#chap_8">5</a></td> -</tr> -<tr> - <td class="tdl">Davy’s Discoveries</td> - <td class="tdr"><a href="#chap_9">5</a></td> -</tr> -<tr> - <td class="tdl">Researches of Oersted, Ampère, Schweigger and Sturgeon</td> - <td class="tdr"><a href="#chap_10">6</a></td> -</tr> -<tr> - <td class="tdl">Ohm’s Law</td> - <td class="tdr"><a href="#chap_11">7</a></td> -</tr> -<tr> - <td class="tdl">Invention of the Dynamo</td> - <td class="tdr"><a href="#chap_12">7</a></td> -</tr> -<tr> - <td class="tdl">Daniell’s Battery</td> - <td class="tdr"><a href="#chap_13">10</a></td> -</tr> -<tr> - <td class="tdl">Grove’s Battery</td> - <td class="tdr"><a href="#chap_14">11</a></td> -</tr> -<tr> - <td class="tdl">Grove’s Demonstration of Incandescent Lighting</td> - <td class="tdr"><a href="#chap_15">12</a></td> -</tr> -<tr> - <td class="tdl">Grenet Battery</td> - <td class="tdr"><a href="#chap_16">13</a></td> -</tr> -<tr> - <td class="tdl">De Moleyns’ Incandescent Lamp</td> - <td class="tdr"><a href="#chap_17">13</a></td> -</tr> -<tr> - <td class="tdl">Early Developments of the Arc Lamp</td> - <td class="tdr"><a href="#chap_18">14</a></td> -</tr> -<tr> - <td class="tdl">Joule’s Law</td> - <td class="tdr"><a href="#chap_19">16</a></td> -</tr> -<tr> - <td class="tdl">Starr’s Incandescent Lamp</td> - <td class="tdr"><a href="#chap_20">17</a></td> -</tr> -<tr> - <td class="tdl">Other Early Incandescent Lamps</td> - <td class="tdr"><a href="#chap_21">19</a></td> -</tr> -<tr> - <td class="tdl">Further Arc Lamp Developments</td> - <td class="tdr"><a href="#chap_22">20</a></td> -</tr> -<tr> - <td class="tdl">Development of the Dynamo, 1840–1860</td> - <td class="tdr"><a href="#chap_23">24</a></td> -</tr> -<tr> - <td class="tdl">The First Commercial Installation of an Electric Light</td> - <td class="tdr"><a href="#chap_24">25</a></td> -</tr> -<tr> - <td class="tdl">Further Dynamo Developments</td> - <td class="tdr"><a href="#chap_25">27</a></td> -</tr> -<tr> - <td class="tdl">Russian Incandescent Lamp Inventors</td> - <td class="tdr"><a href="#chap_26">30</a></td> -</tr> -<tr> - <td class="tdl">The Jablochkoff “Candle”</td> - <td class="tdr"><a href="#chap_27">31</a></td> -</tr> -<tr> - <td class="tdl">Commercial Introduction of the Differentially Controlled Arc Lamp</td> - <td class="tdr"><a href="#chap_28">33</a></td> -</tr> -<tr> - <td class="tdl">Arc Lighting in the United States</td> - <td class="tdr"><a href="#chap_29">33</a></td> -</tr> -<tr> - <td class="tdl">Other American Arc Light Systems</td> - <td class="tdr"><a href="#chap_30">40</a></td> -</tr> -<tr> - <td class="tdl">“Sub-Dividing the Electric Light”</td> - <td class="tdr"><a href="#chap_31">42</a></td> -</tr> -<tr> - <td class="tdl">Edison’s Invention of a Practical Incandescent Lamp</td> - <td class="tdr"><a href="#chap_32">43</a></td> -</tr> -<tr> - <td class="tdl">Edison’s Three-Wire System</td> - <td class="tdr"><a href="#chap_33">53</a></td> -</tr> -<tr> - <td class="tdl">Development of the Alternating Current Constant Potential System</td> - <td class="tdr"><a href="#chap_34">54</a></td> -</tr> -<tr> - <td class="tdl">Incandescent Lamp Developments, 1884–1894</td> - <td class="tdr"><a href="#chap_35">56</a></td> -</tr> -<tr> - <td class="tdl">The Edison “Municipal” Street Lighting System</td> - <td class="tdr"><a href="#chap_36">62</a></td> -</tr> -<tr> - <td class="tdl">The Shunt Box System for Series Incandescent Lamps</td> - <td class="tdr"><a href="#chap_37">64</a></td> -</tr> -<tr> - <td class="tdl">The Enclosed Arc Lamp</td> - <td class="tdr"><a href="#chap_38">65</a></td> -</tr> -<tr> - <td class="tdl">The Flame Arc Lamp</td> - <td class="tdr"><a href="#chap_39">67</a></td> -</tr> -<tr> - <td class="tdl">The Constant Current Transformer for Series Circuits</td> - <td class="tdr"><a href="#chap_40">69</a></td> -</tr> -<tr> - <td class="tdl">Enclosed Series Alternating Current Arc Lamps</td> - <td class="tdr"><a href="#chap_41">69</a></td> -</tr> -<tr> - <td class="tdl">Series Incandescent Lamps on Constant Current Transformers</td> - <td class="tdr"><a href="#chap_42">70</a></td> -</tr> -<tr> - <td class="tdl">The Nernst Lamp</td> - <td class="tdr"><a href="#chap_43">71</a></td> -</tr> -<tr> - <td class="tdl">The Cooper-Hewitt Lamp</td> - <td class="tdr"><a href="#chap_44">72</a></td> -</tr> -<tr> - <td class="tdl">The Luminous or Magnetite Arc Lamp</td> - <td class="tdr"><a href="#chap_45">74</a></td> -</tr> -<tr> - <td class="tdl">Mercury Arc Rectifier for Magnetite Arc Lamps</td> - <td class="tdr"><a href="#chap_46">77</a><span class="pagenum" id="Page_iv">iv</span></td> -</tr> -<tr> - <td class="tdl">Incandescent Lamp Developments, 1894–1904</td> - <td class="tdr"><a href="#chap_47">78</a></td> -</tr> -<tr> - <td class="tdl">The Moore Tube Light</td> - <td class="tdr"><a href="#chap_48">79</a></td> -</tr> -<tr> - <td class="tdl">The Osmium Lamp</td> - <td class="tdr"><a href="#chap_49">82</a></td> -</tr> -<tr> - <td class="tdl">The Gem Lamp</td> - <td class="tdr"><a href="#chap_50">82</a></td> -</tr> -<tr> - <td class="tdl">The Tantalum Lamp</td> - <td class="tdr"><a href="#chap_51">84</a></td> -</tr> -<tr> - <td class="tdl">Invention of the Tungsten Lamp</td> - <td class="tdr"><a href="#chap_52">85</a></td> -</tr> -<tr> - <td class="tdl">Drawn Tungsten Wire</td> - <td class="tdr"><a href="#chap_53">87</a></td> -</tr> -<tr> - <td class="tdl">The Quartz Mercury Vapor Arc Lamp</td> - <td class="tdr"><a href="#chap_54">88</a></td> -</tr> -<tr> - <td class="tdl">The Gas-Filled Tungsten Lamp</td> - <td class="tdr"><a href="#chap_55">89</a></td> -</tr> -<tr> - <td class="tdl">Types and Sizes of Tungsten Lamps Now Made</td> - <td class="tdr"><a href="#chap_56">91</a></td> -</tr> -<tr> - <td class="tdl">Standard Voltages</td> - <td class="tdr"><a href="#chap_57">93</a></td> -</tr> -<tr> - <td class="tdl">Cost of Incandescent Electric Light</td> - <td class="tdr"><a href="#chap_58">93</a></td> -</tr> -<tr> - <td class="tdl">Statistics Regarding the Present Demand for Lamps</td> - <td class="tdr"><a href="#chap_59">94</a></td> -</tr> -<tr> - <td class="tdl">Selected Bibliography</td> - <td class="tdr"><a href="#chap_60">95</a></td> -</tr> -</table> - -<hr class="chap x-ebookmaker-drop" /> - -<div id="chap_1" class="chapter"> -<p><span class="pagenum" id="Page_v">v</span></p> - -<h2 class="nobreak" id="LIST_OF_ILLUSTRATIONS">LIST OF ILLUSTRATIONS</h2> -</div> - -<table id="loi"> -<tr class="small"> - <td> </td> - <td class="tdr">PAGE</td> -</tr> -<tr> - <td class="tdl">Portion of the Electrical Exhibit in the United States National Museum</td> - <td class="tdr"><a href="#i_1">viii</a></td> -</tr> -<tr> - <td class="tdl">Otto Von Guericke’s Electric Machine, 1650</td> - <td class="tdr"><a href="#i_2">2</a></td> -</tr> -<tr> - <td class="tdl">Voltaic Pile, 1799</td> - <td class="tdr"><a href="#i_3">4</a></td> -</tr> -<tr> - <td class="tdl">Faraday’s Dynamo, 1831</td> - <td class="tdr"><a href="#i_4">8</a></td> -</tr> -<tr> - <td class="tdl">Pixii’s Dynamo, 1832</td> - <td class="tdr"><a href="#i_5">9</a></td> -</tr> -<tr> - <td class="tdl">Daniell’s Cell, 1836</td> - <td class="tdr"><a href="#i_6">10</a></td> -</tr> -<tr> - <td class="tdl">Grove’s Cell, 1838</td> - <td class="tdr"><a href="#i_7">11</a></td> -</tr> -<tr> - <td class="tdl">Grove’s Incandescent Lamp, 1840</td> - <td class="tdr"><a href="#i_8">13</a></td> -</tr> -<tr> - <td class="tdl">De Moleyns’ Incandescent Lamp, 1841</td> - <td class="tdr"><a href="#i_9">14</a></td> -</tr> -<tr> - <td class="tdl">Wright’s Arc Lamp, 1845</td> - <td class="tdr"><a href="#i_10">15</a></td> -</tr> -<tr> - <td class="tdl">Archereau’s Arc Lamp, 1848</td> - <td class="tdr"><a href="#i_11">16</a></td> -</tr> -<tr> - <td class="tdl">Starr’s Incandescent Lamp, 1845</td> - <td class="tdr"><a href="#i_12">18</a></td> -</tr> -<tr> - <td class="tdl">Staite’s Incandescent Lamp, 1848</td> - <td class="tdr"><a href="#i_13">19</a></td> -</tr> -<tr> - <td class="tdl">Roberts’ Incandescent Lamp, 1852</td> - <td class="tdr"><a href="#i_14">19</a></td> -</tr> -<tr> - <td class="tdl">Farmer’s Incandescent Lamp, 1859</td> - <td class="tdr"><a href="#i_15">20</a></td> -</tr> -<tr> - <td class="tdl">Roberts’ Arc Lamp, 1852</td> - <td class="tdr"><a href="#i_16">21</a></td> -</tr> -<tr> - <td class="tdl">Slater and Watson’s Arc Lamp, 1852</td> - <td class="tdr"><a href="#i_17">21</a></td> -</tr> -<tr> - <td class="tdl">Diagram of “Differential” Method of Control of an Arc Lamp</td> - <td class="tdr"><a href="#i_18">22</a></td> -</tr> -<tr> - <td class="tdl">Lacassagne and Thiers’ Differentially Controlled Arc Lamp, 1856</td> - <td class="tdr"><a href="#i_19">23</a></td> -</tr> -<tr> - <td class="tdl">Serrin’s Arc Lamp, 1857</td> - <td class="tdr"><a href="#i_20">24</a></td> -</tr> -<tr> - <td class="tdl">Siemens’ Dynamo, 1856</td> - <td class="tdr"><a href="#i_21">25</a></td> -</tr> -<tr> - <td class="tdl">Alliance Dynamo, 1862</td> - <td class="tdr"><a href="#i_22">26</a></td> -</tr> -<tr> - <td class="tdl">Wheatstone’s Self-Excited Dynamo, 1866</td> - <td class="tdr"><a href="#i_23">27</a></td> -</tr> -<tr> - <td class="tdl">Gramme’s Dynamo, 1871</td> - <td class="tdr"><a href="#i_24">28</a></td> -</tr> -<tr> - <td class="tdl">Gramme’s “Ring” Armature</td> - <td class="tdr"><a href="#i_25">28</a></td> -</tr> -<tr> - <td class="tdl">Alteneck’s Dynamo with “Drum” Wound Armature, 1872</td> - <td class="tdr"><a href="#i_26">29</a></td> -</tr> -<tr> - <td class="tdl">Lodyguine’s Incandescent Lamp, 1872</td> - <td class="tdr"><a href="#i_27">30</a></td> -</tr> -<tr> - <td class="tdl">Konn’s Incandescent Lamp, 1875</td> - <td class="tdr"><a href="#i_28">30</a></td> -</tr> -<tr> - <td class="tdl">Bouliguine’s Incandescent Lamp, 1876</td> - <td class="tdr"><a href="#i_29">31</a></td> -</tr> -<tr> - <td class="tdl">Jablochkoff “Candle,” 1876</td> - <td class="tdr"><a href="#i_30">32</a></td> -</tr> -<tr> - <td class="tdl">Jablochkoff’s Alternating Current Dynamo, 1876</td> - <td class="tdr"><a href="#i_31">33</a></td> -</tr> -<tr> - <td class="tdl">Wallace-Farmer Arc Lamp, 1875</td> - <td class="tdr"><a href="#i_32">34</a></td> -</tr> -<tr> - <td class="tdl">Wallace-Farmer Dynamo, 1875</td> - <td class="tdr"><a href="#i_33">34</a></td> -</tr> -<tr> - <td class="tdl">Weston’s Arc Lamp, 1876</td> - <td class="tdr"><a href="#i_34">35</a></td> -</tr> -<tr> - <td class="tdl">Brush’s Dynamo, 1877</td> - <td class="tdr"><a href="#i_35">36</a></td> -</tr> -<tr> - <td class="tdl">Diagram of Brush Armature</td> - <td class="tdr"><a href="#i_36">36</a></td> -</tr> -<tr> - <td class="tdl">Brush’s Arc Lamp, 1877</td> - <td class="tdr"><a href="#i_37">37</a></td> -</tr> -<tr> - <td class="tdl">Thomson-Houston Arc Dynamo, 1878</td> - <td class="tdr"><a href="#i_38">38</a></td> -</tr> -<tr> - <td class="tdl">Diagram of T-H Arc Lighting System</td> - <td class="tdr"><a href="#i_39">39</a></td> -</tr> -<tr> - <td class="tdl">Thomson-Houston Arc Lamp, 1878</td> - <td class="tdr"><a href="#i_40">40</a></td> -</tr> -<tr> - <td class="tdl">Thomson Double Carbon Arc Lamp</td> - <td class="tdr"><a href="#i_41">40</a></td> -</tr> -<tr> - <td class="tdl">Maxim Dynamo</td> - <td class="tdr"><a href="#i_42">41</a></td> -</tr> -<tr> - <td class="tdl">Sawyer’s Incandescent Lamp, 1878</td> - <td class="tdr"><a href="#i_43">42</a></td> -</tr> -<tr> - <td class="tdl">Farmer’s Incandescent Lamp, 1878</td> - <td class="tdr"><a href="#i_44">42</a></td> -</tr> -<tr> - <td class="tdl">Maxim’s Incandescent Lamp, 1878</td> - <td class="tdr"><a href="#i_45">43</a></td> -</tr> -<tr> - <td class="tdl">Edison’s First Experimental Lamp, 1878</td> - <td class="tdr"><a href="#i_46">44<span class="pagenum" id="Page_vi">vi</span></a></td> -</tr> -<tr> - <td class="tdl">Diagram of Constant Current Series System</td> - <td class="tdr"><a href="#i_47">45</a></td> -</tr> -<tr> - <td class="tdl">Diagram of Edison’s Multiple System, 1879</td> - <td class="tdr"><a href="#i_48">45</a></td> -</tr> -<tr> - <td class="tdl">Edison Dynamo, 1879</td> - <td class="tdr"><a href="#i_49">46</a></td> -</tr> -<tr> - <td class="tdl">Edison’s High Resistance Platinum Lamp, 1879</td> - <td class="tdr"><a href="#i_50">47</a></td> -</tr> -<tr> - <td class="tdl">Edison’s High Resistance Platinum in Vacuum Lamp, 1879</td> - <td class="tdr"><a href="#i_51">47</a></td> -</tr> -<tr> - <td class="tdl">Edison’s Carbon Lamp of October 21, 1879</td> - <td class="tdr"><a href="#i_52">48</a></td> -</tr> -<tr> - <td class="tdl">Demonstration of Edison’s Incandescent Lighting System</td> - <td class="tdr"><a href="#i_53">49</a></td> -</tr> -<tr> - <td class="tdl">Dynamo Room, S. S. Columbia</td> - <td class="tdr"><a href="#i_54">50</a></td> -</tr> -<tr> - <td class="tdl">Original Socket for Incandescent Lamps</td> - <td class="tdr"><a href="#i_55">51</a></td> -</tr> -<tr> - <td class="tdl">Wire Terminal Base Lamp, 1880</td> - <td class="tdr"><a href="#i_56">51</a></td> -</tr> -<tr> - <td class="tdl">Original Screw Base Lamp, 1880</td> - <td class="tdr"><a href="#i_57">52</a></td> -</tr> -<tr> - <td class="tdl">Improved Screw Base Lamp, 1881</td> - <td class="tdr"><a href="#i_58">52</a></td> -</tr> -<tr> - <td class="tdl">Final Form of Screw Base, 1881</td> - <td class="tdr"><a href="#i_59">53</a></td> -</tr> -<tr> - <td class="tdl">Diagram of Edison’s Three Wire System, 1881</td> - <td class="tdr"><a href="#i_60">54</a></td> -</tr> -<tr> - <td class="tdl">Diagram of Stanley’s Alternating Current Multiple System, 1885</td> - <td class="tdr"><a href="#i_61">55</a></td> -</tr> -<tr> - <td class="tdl">Standard Edison Lamp, 1884</td> - <td class="tdr"><a href="#i_62">56</a></td> -</tr> -<tr> - <td class="tdl">Standard Edison Lamp, 1888</td> - <td class="tdr"><a href="#i_63">56</a></td> -</tr> -<tr> - <td class="tdl">Standard Edison Lamp, 1894</td> - <td class="tdr"><a href="#i_64">57</a></td> -</tr> -<tr> - <td class="tdl">Various Bases in Use, 1892</td> - <td class="tdr"><a href="#i_65">58</a></td> -</tr> -<tr> - <td class="tdl">Thomson-Houston Socket</td> - <td class="tdr"><a href="#i_66">59</a></td> -</tr> -<tr> - <td class="tdl">Westinghouse Socket</td> - <td class="tdr"><a href="#i_67">59</a></td> -</tr> -<tr> - <td class="tdl">Adapters for Edison Screw Sockets, 1892</td> - <td class="tdr"><a href="#i_68">60</a></td> -</tr> -<tr> - <td class="tdl">Various Series Bases in Use, 1892</td> - <td class="tdr"><a href="#i_69">61</a></td> -</tr> -<tr> - <td class="tdl">Edison “Municipal” System, 1885</td> - <td class="tdr"><a href="#i_70">62</a></td> -</tr> -<tr> - <td class="tdl">Edison “Municipal” Lamp, 1885</td> - <td class="tdr"><a href="#i_71">63</a></td> -</tr> -<tr> - <td class="tdl">Shunt Box System, 1887</td> - <td class="tdr"><a href="#i_72">64</a></td> -</tr> -<tr> - <td class="tdl">Enclosed Arc Lamp, 1893</td> - <td class="tdr"><a href="#i_73">65</a></td> -</tr> -<tr> - <td class="tdl">Open Flame Arc Lamp, 1898</td> - <td class="tdr"><a href="#i_74">66</a></td> -</tr> -<tr> - <td class="tdl">Enclosed Flame Arc Lamp, 1908</td> - <td class="tdr"><a href="#i_75">66</a></td> -</tr> -<tr> - <td class="tdl">Constant Current Transformer, 1900</td> - <td class="tdr"><a href="#i_76">68</a></td> -</tr> -<tr> - <td class="tdl">Series Incandescent Lamp Socket with Film Cutout, 1900</td> - <td class="tdr"><a href="#i_77">70</a></td> -</tr> -<tr> - <td class="tdl">Nernst Lamp, 1900</td> - <td class="tdr"><a href="#i_78">71</a></td> -</tr> -<tr> - <td class="tdl">Diagram of Nernst Lamp</td> - <td class="tdr"><a href="#i_79">72</a></td> -</tr> -<tr> - <td class="tdl">Cooper-Hewitt Mercury Vapor Arc Lamp, 1901</td> - <td class="tdr"><a href="#i_80">73</a></td> -</tr> -<tr> - <td class="tdl">Diagram of Cooper-Hewitt Lamp for Use on Alternating Current</td> - <td class="tdr"><a href="#i_81">74</a></td> -</tr> -<tr> - <td class="tdl">Luminous or Magnetite Arc Lamp, 1902</td> - <td class="tdr"><a href="#i_82">75</a></td> -</tr> -<tr> - <td class="tdl">Diagram of Series Magnetite Arc Lamp</td> - <td class="tdr"><a href="#i_83">76</a></td> -</tr> -<tr> - <td class="tdl">Mercury Arc Rectifier Tube for Series Magnetite Arc Circuits, 1902</td> - <td class="tdr"><a href="#i_84">77</a></td> -</tr> -<tr> - <td class="tdl">Early Mercury Arc Rectifier Installation</td> - <td class="tdr"><a href="#i_85">78</a></td> -</tr> -<tr> - <td class="tdl">The Moore Tube Light, 1904</td> - <td class="tdr"><a href="#i_86">79</a></td> -</tr> -<tr> - <td class="tdl">Diagram of Feeder Valve of Moore Tube</td> - <td class="tdr"><a href="#i_87">80</a></td> -</tr> -<tr> - <td class="tdl">Osmium Lamp, 1905</td> - <td class="tdr"><a href="#i_88">82</a></td> -</tr> -<tr> - <td class="tdl">Gem Lamp, 1905</td> - <td class="tdr"><a href="#i_89">83</a></td> -</tr> -<tr> - <td class="tdl">Tantalum Lamp, 1906</td> - <td class="tdr"><a href="#i_90">84</a></td> -</tr> -<tr> - <td class="tdl">Tungsten Lamp, 1907</td> - <td class="tdr"><a href="#i_91">86</a></td> -</tr> -<tr> - <td class="tdl">Drawn Tungsten Wire Lamp, 1911</td> - <td class="tdr"><a href="#i_92">87</a></td> -</tr> -<tr> - <td class="tdl">Quartz Mercury Vapor Lamp, 1912</td> - <td class="tdr"><a href="#i_93">88</a></td> -</tr> -<tr> - <td class="tdl">Gas Filled Tungsten Lamp, 1913</td> - <td class="tdr"><a href="#i_94">89</a></td> -</tr> -<tr> - <td class="tdl">Gas Filled Tungsten Lamp, 1923</td> - <td class="tdr"><a href="#i_95">90</a></td> -</tr> -<tr> - <td class="tdl">Standard Tungsten Lamps, 1923</td> - <td class="tdr"><a href="#i_96">92</a></td> -</tr> -</table> - -<p><span class="pagenum" id="Page_viii">viii</span></p> - -<div id="i_1" class="newpage p4 figcenter"> - <img src="images/i_001.jpg" width="3044" height="1485" style="width: 80%;" alt="" /> - <div class="caption"><p><span class="smcap">Portion of the Electrical Exhibit in the United States National Museum.</span></p> - -<p>Section devoted to the historical development of the electric light and dynamo.</p></div></div> - -<hr class="chap x-ebookmaker-drop" /> - -<div id="chap_2" class="chapter"> -<p><span class="pagenum" id="Page_ix">ix</span></p> - -<h2 class="nobreak" id="FOREWORD">FOREWORD</h2> -</div> - -<p>In the year 1884 a Section of Transportation was organized in -the United States National Museum for the purpose of preparing -and assembling educational exhibits of a few objects of railroad -machinery which had been obtained both from the Centennial Exhibition -held in Philadelphia in 1876 and still earlier as incidentals to -ethnological collections, and to secure other collections relating to the -railway industry.</p> - -<p>From this beginning the section was expanded to include the -whole field of engineering and is designated at present as the Divisions -of Mineral and Mechanical Technology. The growth and enlargement -of the collections has been particularly marked in the fields of -mining and mineral industries; mechanical engineering, especially -pertaining to the steam engine, internal combustion engine and locomotive; -naval architecture, and electrical engineering, particularly the -development of the telegraph, telephone and the electric light.</p> - -<p>In the acquisition of objects visualizing the history of electric -light the Museum has been rather fortunate, particularly as regards -the developments in the United States. Thus mention may be made -of the original Patent Office models of the more important dynamos, -arc lights and incandescent lights, together with original commercial -apparatus after these models; a unit of the equipment used in the first -commercially successful installation on land of an incandescent lighting -system, presented by Joseph E. Hinds in whose engraving establishment -in New York City the installation was made in 1881; and a large -series of incandescent lights, mainly originals, visualizing chronologically -the developments of the Edison light from its inception, presented -at intervals since the year 1898 by the General Electric -Company.</p> - -<p>The object of all collections in the Divisions is to visualize broadly -the steps by which advances have been made in each field of engineering; -to show the layman the fundamental and general principles which -are the basis for the developments; and to familiarize the engineer -with branches of engineering other than his own. Normally when a -subject is completely covered by a collection of objects, a paper is prepared -and published describing the collection and the story it portrays. -In the present instance, however, on account of the uncertainty of<span class="pagenum" id="Page_x">x</span> -the time of completing the collection, if it is possible ever to bring this -about, it was thought advisable to publish Mr. Schroeder’s paper -which draws upon the Museum collection as completely as possible.</p> - -<p class="right l1"> -<span style="margin-right: 8em;"><span class="smcap">Carl W. Mitman</span>,</span><br /> -<i>Curator, Divisions of Mineral and</i><br /> -<span style="margin-right: 2em;"><i>Mechanical Technology,</i></span><br /> -<span style="margin-right: .5em;"><i>U. S. National Museum</i>.</span> -</p> - -<hr class="chap x-ebookmaker-drop" /> - -<div id="chap_3" class="chapter"> -<p><span class="pagenum" id="Page_xi">xi</span></p> - -<h2 class="nobreak" id="CHRONOLOGY_OF_ELECTRIC_LIGHT">CHRONOLOGY OF ELECTRIC LIGHT</h2> -</div> - -<div class="blockquot hang2"> - -<p>1800—Allesandro Volta demonstrated his discovery that electricity -can be generated by chemical means. The <span class="smcap">Volt</span>, the unit -of electric pressure, is named in his honor for this discovery -of the electric battery.</p> - -<p>1802—Sir Humphry Davy demonstrated that electric current can heat -carbon and strips of metal to incandescence and give light.</p> - -<p>1809—Sir Humphry Davy demonstrated that current will give a brilliant -flame between the ends of two carbon pencils which are -first allowed to touch each other and then pulled apart. This -light he called the “arc” on account of its arch shape.</p> - -<p>1820—André Marie Ampère discovered that current flowing through -a coiled wire gives it the properties of a magnet. The <span class="smcap">Ampere</span>, -the unit of flow of electric current, is named in his -honor for this discovery.</p> - -<p>1825—Georg Simon Ohm discovered the relation between the voltage, -ampereage and resistance in an electric circuit, which is -called Ohm’s Law. The <span class="smcap">Ohm</span>, the unit of electric resistance, -is named in his honor for this discovery.</p> - -<p>1831—Michael Faraday discovered that electricity can be generated -by moving a wire in the neighborhood of a magnet, the -principle of the dynamo.</p> - -<p>1840—Sir William Robert Grove demonstrated his experimental -incandescent lamp in which platinum is made incandescent -by current flowing through it.</p> - -<p>1841—Frederick De Moleyns obtained the first patent on an incandescent -lamp. The burner was powdered charcoal operating -in an exhausted glass globe.</p> - -<p>1845—Thomas Wright obtained the first patent on an arc light.</p> - -<p>1845—J. W. Starr invented an incandescent lamp consisting of a -carbon pencil operating in the vacuum above a column of -mercury.</p> - -<p>1856—Joseph Lacassagne and Henry Thiers invented the “differential” -method of control of the arc which was universally -used twenty years later when the arc lamp was commercially -established.</p> - -<p>1862—The first commercial installation of an electric light. An arc -light was put in a lighthouse in England.</p> - -<p><span class="pagenum" id="Page_xii">xii</span></p> - -<p>1866—Sir Charles Wheatstone invented the “self-excited” dynamo, -now universally used.</p> - -<p>1872—Lodyguine invented an incandescent lamp having a graphite -burner operating in nitrogen gas.</p> - -<p>1876—Paul Jablochkoff invented the “electric candle,” an arc light -commercially used for lighting the boulevards in Paris.</p> - -<p>1877–8—Arc light systems commercially established in the United -States by William Wallace and Prof. Moses Farmer, Edward -Weston, Charles F. Brush and Prof. Elihu Thomson and -Edwin J. Houston.</p> - -<p>1879—Thomas Alva Edison invented an incandescent lamp consisting -of a high resistance carbon filament operating in a high -vacuum maintained by an all glass globe. These principles -are used in all incandescent lamps made today. He also -invented a completely new system of distributing electricity -at constant pressure, now universally used.</p> - -<p>1882—Lucien Goulard and John D. Gibbs invented a series alternating -current system of distributing electric current. This has -not been commercially used.</p> - -<p>1886—William Stanley invented a constant pressure alternating current -system of distribution. This is universally used where -current is to be distributed long distances.</p> - -<p>1893—Louis B. Marks invented the enclosed carbon arc lamp.</p> - -<p>1898—Bremer’s invention of the flame arc lamp, having carbons impregnated -with various salts, commercially established.</p> - -<p>1900—Dr. Walther Nernst’s invention of the Nernst lamp commercially -established. The burner consisted of various oxides, -such as zirconia, which operated in the open air.</p> - -<p>1901—Dr. Peter Cooper Hewitt’s invention of the mercury arc light -commercially established.</p> - -<p>1902—The magnetite arc lamp was developed by C. A. B. Halvorson, -Jr. This has a new method of control of the arc. The -negative electrode consists of a mixture of magnetite and -other substances packed in an iron tube.</p> - -<p>1904—D. McFarlan Moore’s invention of the Moore vacuum tube -light commercially established. This consisted of a long -tube, made in lengths up to 200 feet, from which the air -had been exhausted to about a thousandth of an atmosphere. -High voltage current passing through this rarefied atmosphere -caused it to glow. Rarefied carbon dioxide gas was -later used.</p> - -<p><span class="pagenum" id="Page_xiii">xiii</span></p> - -<p>1905—Dr. Auer von Welsbach’s invention of the osmium incandescent -lamp commercially established, but only on a small scale -in Europe. The metal osmium, used for the filament which -operated in vacuum, is rarer and more expensive than platinum.</p> - -<p>1905—Dr. Willis R. Whitney’s invention of the Gem incandescent -lamp commercially established. The carbon filament had -been heated to a very high temperature in an electric resistance -furnace invented by him. The lamp was 25 per cent -more efficient than the regular carbon lamp.</p> - -<p>1906—Dr. Werner von Bolton’s invention of the tantalum incandescent -lamp commercially established.</p> - -<p>1907—Alexander Just and Franz Hanaman’s invention of the tungsten -filament incandescent lamp commercially established.</p> - -<p>1911—Dr. William D. Coolidge’s invention of drawn tungsten wire -commercially established.</p> - -<p>1913—Dr. Irving Langmuir’s invention of the gas-filled tungsten -filament incandescent lamp commercially established.</p> -</div> - -<hr class="chap x-ebookmaker-drop" /> - -<div id="chap_4" class="chapter"> -<p><span class="pagenum" id="Page_1">1</span></p> - -<h2 class="nobreak" id="HISTORY_OF_ELECTRIC_LIGHT"><span class="larger">HISTORY OF ELECTRIC LIGHT</span></h2> -</div> - -<p class="center wspace"><span class="smcap">By</span> HENRY SCHROEDER,<br /> -HARRISON, NEW JERSEY.</p> - -<h2 class="nobreak" id="EARLY_RECORDS_OF_ELECTRICITY_AND_MAGNETISM">EARLY RECORDS OF ELECTRICITY AND MAGNETISM</h2> - -<p>About twenty-five centuries ago, Thales, a Greek philosopher, -recorded the fact that if amber is rubbed it will attract light objects. -The Greeks called amber “elektron,” from which we get the word -“electricity.” About two hundred and fifty years later, Aristotle, -another Greek philosopher, mentioned that the lodestone would attract -iron. Lodestone is an iron ore (Fe<sub>3</sub>O<sub>4</sub>), having magnetic qualities -and is now called magnetite. The word “magnet” comes from the -fact that the best specimens of lodestones came from Magnesia, a -city in Asia Minor. Plutarch, a Greek biographer, wrote about -100 A. D., that iron is sometimes attracted and at other times repelled -by a lodestone. This indicates that the piece of iron was magnetised -by the lodestone.</p> - -<p>In 1180, Alexander Neckham, an English Monk, described the -compass, which probably had been invented by sailors of the northern -countries of Europe, although its invention has been credited to the -Chinese. Early compasses probably consisted of an iron needle, -magnetised by a lodestone, mounted on a piece of wood floating in -water. The word lodestone or “leading stone” comes from the fact -that it would point towards the north if suspended like a compass.</p> - -<p>William Gilbert, physician to Queen Elizabeth of England, wrote a -book about the year 1600 giving all the information then known on -the subject. He also described his experiments, showing, among -other things, the existence of magnetic lines of force and of north and -south poles in a magnet. Robert Norman had discovered a few years -previously that a compass needle mounted on a horizontal axis would -dip downward. Gilbert cut a large lodestone into a sphere, and -observed that the needle did not dip at the equator of this sphere, the -dip increasing to 90 degrees as the poles were approached. From -this he deduced that the earth was a magnet with the magnetic north -pole at the geographic north pole. It has since been determined that -these two poles do not coincide. Gilbert suggested the use of the -dipping needle to determine latitude. He also discovered that other -substances, beside amber, would attract light objects if rubbed.</p> - -<hr class="chap x-ebookmaker-drop" /> - -<div id="chap_5" class="chapter"> -<p><span class="pagenum" id="Page_2">2</span></p> - -<h2 class="nobreak" id="MACHINES_GENERATING_ELECTRICITY_BY_FRICTION">MACHINES GENERATING ELECTRICITY BY FRICTION</h2> -</div> - -<p>Otto Von Guericke was mayor of the city of Magdeburg as well as -a philosopher. About 1650 he made a machine consisting of a ball -of sulphur mounted on a shaft which could be rotated. Electricity -was generated when the hand was pressed against the globe as it -rotated. He also discovered that electricity could be conducted away -from the globe by a chain and would appear at the other end of the -chain. Von Guericke also invented the vacuum air pump. In 1709, -Francis Hawksbee, an Englishman, made a similar machine, using a -hollow glass globe which could be exhausted. The exhausted globe -when rotated at high speed and rubbed by hand would produce a glowing -light. This “electric light” as it was called, created great excitement -when it was shown before the Royal Society, a gathering of -scientists, in London.</p> - -<div id="i_2" class="figcenter"> - <img src="images/i_002.jpg" width="1697" height="1103" style="width: 70%;" alt="" /> - <div class="caption"><p><span class="smcap">Otto Von Guericke’s Electric Machine, 1650.</span></p> - -<p>A ball of sulphur was rotated, electricity being generated when it -rubbed against the hand.</p></div></div> - -<p>Stephen Gray, twenty years later, showed the Royal Society that -electricity could be conducted about a thousand feet by a hemp thread, -supported by silk threads. If metal supports were used, this could not -be done. Charles du Fay, a Frenchman, repeated Gray’s experiments, -and showed in 1733 that the substances which were insulators, and<span class="pagenum" id="Page_3">3</span> -which Gilbert had discovered, would become electrified if rubbed. -Those substances which Gilbert could not electrify were conductors -of electricity.</p> - -<hr class="chap x-ebookmaker-drop" /> - -<div id="chap_6" class="chapter"> -<h2 class="nobreak" id="THE_LEYDEN_JAR">THE LEYDEN JAR</h2> -</div> - -<p>The thought came to Von Kleist, Bishop of Pomerania, Germany, -about 1745, that electricity could be stored. The frictional machines -generated so small an amount of electricity (though, as is now known, -at a very high pressure—several thousand volts) that he thought he -could increase the quantity by storing it. Knowing that glass was -an insulator and water a conductor, he filled a glass bottle partly full -of water with a nail in the cork to connect the machine with the -water. Holding the bottle in one hand and turning the machine with -the other for a few minutes, he then disconnected the bottle from the -machine. When he touched the nail with his other hand he received -a shock which nearly stunned him. This was called the Leyden jar, -the forerunner of the present condenser. It received its name from -the fact that its discovery was also made a short time after by experimenters -in the University of Leyden. Further experiments showed -that the hand holding the bottle was as essential as the water inside, -so these were substituted by tin foil coatings inside and outside the -bottle.</p> - -<p>Benjamin Franklin, American statesman, scientist and printer, made -numerous experiments with the Leyden jar. He connected several -jars in parallel, as he called it, which gave a discharge strong enough -to kill a turkey. He also connected the jars in series, or “in cascade” -as he called it, thus establishing the principle of parallel and series -connections. Noticing the similarity between the electric spark and -lightning, Franklin in 1752, performed his famous kite experiment. -Flying a kite in a thunderstorm, he drew electricity from the clouds -to charge Leyden jars, which were later discharged, proving that -lightning and electricity were the same. This led him to invent the -lightning rod.</p> - -<hr class="chap x-ebookmaker-drop" /> - -<div id="chap_7" class="chapter"> -<h2 class="nobreak" id="ELECTRICITY_GENERATED_BY_CHEMICAL_MEANS">ELECTRICITY GENERATED BY CHEMICAL MEANS</h2> -</div> - -<p>Luigi Galvani was an Italian scientist. About 1785, so the story -goes, his wife was in delicate health, and some frog legs were being -skinned to make her a nourishing soup. An assistant holding the legs -with a metal clamp and cutting the skin with a scalpel, happened to -let the clamp and scalpel touch each other. To his amazement the -frog legs twitched. Galvani repeated the experiment many times<span class="pagenum" id="Page_4">4</span> -by touching the nerve with a metal rod and the muscle with a different -metal rod and allowing the rods to touch, and propounded the theory -of animal electricity in a paper he published in 1791.</p> - -<p>Allesandro Volta, a professor of physics in the University of Pavia, -Italy, read about Galvani’s work and repeated his experiments. He -found that the extent of the movement of the frog legs depended -on the metals used for the rods, and thus believed that the electric -charge was produced by the contact of dissimilar metals with the -moisture in the muscles. To prove his point he made a pile of silver -and zinc discs with cloths, wet with salt water, between them. This -was in 1799, and he described his pile in March, 1800, in a letter to -the Royal Society in London.</p> - -<div id="i_3" class="figcenter"> - <img src="images/i_004.png" width="620" height="1032" style="width: 26%;" alt="" /> - <div class="caption"><p><span class="smcap">Voltaic Pile, 1799.</span></p> - -<p class="justify">Volta discovered that electricity could be generated by chemical -means and made a pile of silver and zinc discs with cloths, wet with -salt water, between them. This was the forerunner of the present-day -dry battery. Photograph courtesy Prof. Chas. F. Chandler -Museum, Columbia University, New York.</p></div></div> - -<p>This was an epoch-making discovery as it was the forerunner of the -present-day primary battery. Volta soon found that the generation -of electricity became weaker as the cloths became dry, so to overcome -this he made his “crown of cups.” This consisted of a series of -cups containing salt water in which strips of silver and zinc were -dipped. Each strip of silver in one cup was connected to the zinc -strip in the next cup, the end strips of silver and zinc being terminals -of the battery. This was the first time that a continuous supply of<span class="pagenum" id="Page_5">5</span> -electricity in reasonable quantities was made available, so the <span class="smcap">Volt</span>, -the unit of electrical pressure was named in his honor. It was later -shown that the chemical affinity of one of the metals in the liquid -was converted into electric energy. The chemical action of Volta’s -battery is that the salt water attacks the zinc when the circuit is -closed forming zinc chloride, caustic soda and hydrogen gas. The -chemical equation is:</p> - -<p class="center"> -Zn + 2NaCl + 2H<sub>2</sub>O = ZnCl<sub>2</sub> + 2NaOH + H<sub>2</sub> -</p> - -<hr class="chap x-ebookmaker-drop" /> - -<div id="chap_8" class="chapter"> -<h2 class="nobreak" id="IMPROVEMENT_OF_VOLTAS_BATTERY">IMPROVEMENT OF VOLTA’S BATTERY</h2> -</div> - -<p>It was early suggested that sheets of silver and zinc be soldered -together back to back and that a trough be divided into cells by these -bimetal sheets being put into grooves cut in the sides and bottom of the -trough. This is the reason why one unit of a battery is called a “cell.” -It was soon found that a more powerful cell could be made if copper, -zinc and dilute sulphuric acid were used. The zinc is dissolved by -the acid forming zinc sulphate and hydrogen gas, thus:</p> - -<p class="center"> -Zn + H<sub>2</sub>SO<sub>4</sub> = ZnSO<sub>4</sub> + H<sub>2</sub> -</p> - -<p>The hydrogen gas appears as bubbles on the copper and reduces the -open circuit voltage (about 0.8 volt per cell) as current is taken from -the battery. This is called “polarization.” Owing to minute impurities -in the zinc, it is attacked by the acid even when no current is -taken from the battery, the impurities forming with the zinc a short -circuited local cell. This is called “local action,” and this difficulty -was at first overcome by removing the zinc from the acid when the -battery was not in use.</p> - -<hr class="chap x-ebookmaker-drop" /> - -<div id="chap_9" class="chapter"> -<h2 class="nobreak" id="DAVYS_DISCOVERIES">DAVY’S DISCOVERIES</h2> -</div> - -<p>Sir Humphry Davy was a well-known English chemist, and with -the aid of powerful batteries constructed for the Royal Institution in -London, he made numerous experiments on the chemical effects of -electricity. He decomposed a number of substances and discovered -the elements boron, potassium and sodium. He heated strips of -various metals to incandescence by passing current through them, -and showed that platinum would stay incandescent for some time -without oxidizing. This was about 1802.</p> - -<p>In the early frictional machines, the presence of electricity was -shown by the fact that sparks could be obtained. Similarly the breaking -of the circuit of a battery would give a spark. Davy, about 1809, -demonstrated that this spark could be maintained for a long time with<span class="pagenum" id="Page_6">6</span> -the large battery of 2000 cells he had had constructed. Using two -sticks of charcoal connected by wires to the terminals of this very -powerful battery, he demonstrated before the Royal Society the light -produced by touching the sticks together and then holding them apart -horizontally about three inches. The brilliant flame obtained he called -an “arc” because of its arch shape, the heated gases, rising, assuming -this form. Davy was given the degree of LL. D. for his distinguished -research work, and was knighted on the eve of his marriage, -April 11, 1812.</p> - -<hr class="chap x-ebookmaker-drop" /> - -<div id="chap_10" class="chapter"> -<h2 class="nobreak" id="RESEARCHES_OF_OERSTED_AMPERE_SCHWEIGGER_AND_STURGEON">RESEARCHES OF OERSTED, AMPÈRE, SCHWEIGGER AND STURGEON</h2> -</div> - -<p>Hans Christian Oersted was a professor of physics at the University -of Copenhagen in Denmark. One day in 1819, while addressing -his students, he happened to hold a wire, through which -current was flowing, over a large compass. To his surprise he saw -the compass was deflected from its true position. He promptly made -a number of experiments and discovered that by reversing the current -the compass was deflected in the opposite direction. Oersted announced -his discovery in 1820.</p> - -<p>André Marie Ampère was a professor of mathematics in the Ecole -Polytechnic in Paris. Hearing of Oersted’s discovery, he immediately -made some experiments and made the further discovery in 1820 -that if the wire is coiled and current passed through it, the coil had -all the properties of a magnet.</p> - -<p>These two discoveries led to the invention of Schweigger in 1820, -of the galvanometer (or “multiplier” as it was then called), a very -sensitive instrument for measuring electric currents. It consisted of -a delicate compass needle suspended in a coil of many turns of wire. -Current in the coil deflected the needle, the direction and amount of -deflection indicating the direction and strength of the current. -Ampère further made the discovery that currents in opposite directions -repel and in the same directions attract each other. He also gave -a rule for determining the direction of the current by the deflection of -the compass needle. He developed the theory that magnetism is -caused by electricity flowing around the circumference of the body -magnetised. The <span class="smcap">Ampere</span>, the unit of flow of electric current, was -named in honor of his discoveries.</p> - -<p>In 1825 it was shown by Sturgeon that if a bar of iron were placed -in the coil, its magnetic strength would be very greatly increased, -which he called an electro-magnet.</p> - -<hr class="chap x-ebookmaker-drop" /> - -<div id="chap_11" class="chapter"> -<p><span class="pagenum" id="Page_7">7</span></p> - -<h2 class="nobreak" id="OHMS_LAW">OHM’S LAW</h2> -</div> - -<p>Georg Simon Ohm was born in Bavaria, the oldest son of a poor -blacksmith. With the aid of friends he went to college and became -a teacher. It had been shown that the rate of transfer of heat from -one end to the other of a metal bar is proportional to the difference of -temperature between the ends. About 1825, Ohm, by analogy and -experiment, found that the current in a conductor is proportional -to the difference of electric pressure (voltage) between its ends. -He further showed that with a given difference of voltage, the current -in different conductors is inversely proportional to the resistance of -the conductor. Ohm therefore propounded the law that the current -flowing in a circuit is equal to the voltage on that circuit divided by -the resistance of the circuit. In honor of this discovery, the unit of -electrical resistance is called the <span class="smcap">Ohm</span>. This law is usually expressed -as:</p> - -<p class="center"> -C = E/R -</p> - -<p>“C” meaning current (in amperes), “E” meaning electromotive -force or voltage (in volts) and “R” meaning resistance (in ohms).</p> - -<p>This is one of the fundamental laws of electricity and if thoroughly -understood, will solve many electrical problems. Thus, if any two of -the above units are known, the third can be determined. Examples: -An incandescent lamp on a 120-volt circuit consumes 0.4 ampere, -hence its resistance under such conditions is 300 ohms. Several -trolley cars at the end of a line take 100 amperes to run them and the -resistance of the overhead wire from the power house to the trolley -cars is half an ohm; the drop in voltage on the line between the power -house and trolley cars is therefore 50 volts, so that if the voltage at -the power house were 600, it would be 550 volts at the end of the line.</p> - -<p>Critics derided Ohm’s law so that he was forced out of his position -as teacher in the High School in Cologne. Finally after ten years -Ohm began to find supporters and in 1841 his law was publicly -recognized by the Royal Society of London which presented him with -the Copley medal.</p> - -<hr class="chap x-ebookmaker-drop" /> - -<div id="chap_12" class="chapter"> -<h2 class="nobreak" id="INVENTION_OF_THE_DYNAMO">INVENTION OF THE DYNAMO</h2> -</div> - -<p>Michael Faraday was an English scientist. Born of parents in -poor circumstances, he became a bookbinder and studied books on -electricity and chemistry. He finally obtained a position as laboratory -assistant to Sir Humphry Davy helping him with his lectures and<span class="pagenum" id="Page_8">8</span> -experiments. He also made a number of experiments himself and succeeded -in liquifying chlorine gas for which he was elected to a Fellowship -in the Royal Institution in 1824. Following up Oersted’s -and Ampère’s work, he endeavored to find the relation between -electricity and magnetism. Finally on Oct. 17, 1831, he made the -experiment of moving a permanent bar magnet in and out of a coil -of wire connected to a galvanometer. This generated electricity in -the coil which deflected the galvanometer needle. A few days after, -Oct. 28, 1831, he mounted a copper disk on a shaft so that the disk -could be rotated between the poles of a permanent horseshoe magnet. -The shaft and edge of the disk were connected by brushes and wires -to a galvanometer, the needle of which was deflected as the disk was -rotated. A paper on his invention was read before the Royal Society -on November 24, 1831, which appeared in printed form in January, -1832.</p> - -<div id="i_4" class="figcenter"> - <img src="images/i_008.png" width="1337" height="1045" style="width: 56%;" alt="" /> - <div class="caption"><p><span class="smcap">Faraday’s Dynamo, 1831.</span></p> - -<p>Faraday discovered that electricity could be generated by means of a -permanent magnet. This principle is used in all dynamos.</p></div></div> - -<p>Faraday did not develop his invention any further, being satisfied, -as in all his work, in pure research. His was a notable invention but -it remained for others to make it practicable. Hippolyte Pixii, a -Frenchman, made a dynamo in 1832 consisting of a permanent horseshoe -magnet which could be rotated between two wire bobbins -mounted on a soft iron core. The wires from the bobbins were connected<span class="pagenum" id="Page_9">9</span> -to a pair of brushes touching a commutator mounted on the -shaft holding the magnet, and other brushes carried the current from -the commutator so that the alternating current generated was rectified -into direct current.</p> - -<div id="i_5" class="figcenter"> - <img src="images/i_009.png" width="911" height="1429" style="width: 38%;" alt="" /> - <div class="caption"><p><span class="smcap">Pixii’s Dynamo, 1832.</span></p> - -<p class="justify">Pixii made an improvement by rotating a permanent magnet in the -neighborhood of coils of wire mounted on a soft iron core. A commutator -rectified the alternating current generated into direct current. -This dynamo is in the collection of the Smithsonian Institution.</p></div></div> - -<p>E. M. Clarke, an Englishman made, in 1834, another dynamo in -which the bobbins rotated alongside of the poles of a permanent -horseshoe magnet. He also made a commutator so that the machine -produced direct current. None of these machines gave more than -feeble current at low pressure. The large primary batteries that had -been made were much more powerful, although expensive to operate. -It has been estimated that the cost of current from the 2000-cell -battery to operate the demonstration of the arc light by Davy, was -six dollars a minute. At present retail rates for electricity sold by<span class="pagenum" id="Page_10">10</span> -lighting companies, six dollars would operate Davy’s arc light about -500 hours or 30,000 times as long.</p> - -<hr class="chap x-ebookmaker-drop" /> - -<div id="chap_13" class="chapter"> -<h2 class="nobreak" id="DANIELLS_BATTERY">DANIELL’S BATTERY</h2> -</div> - -<div id="i_6" class="figcenter"> - <img src="images/i_010.png" width="497" height="921" style="width: 22%;" alt="" /> - <div class="caption"><p><span class="smcap">Daniell’s Cell, 1836.</span></p> - -<p class="justify">Daniell invented a battery consisting of zinc, copper and copper sulphate. -Later the porous cup was dispensed with, which was used to -keep the sulphuric acid formed separate from the solution of copper -sulphate, the two liquids then being kept apart by their difference in -specific gravity. It was then called the Gravity Battery and for years -was used in telegraphy.</p></div></div> - -<p>It was soon discovered that if the zinc electrode were rubbed with -mercury (amalgamated), the local action would practically cease, -and if the hydrogen bubbles were removed, the operating voltage of -the cell would be increased. John Frederic Daniell, an English -chemist, invented a cell in 1836 to overcome these difficulties. His -cell consisted of a glass jar containing a saturated solution of copper -sulphate (CuSO<sub>4</sub>). A copper cylinder, open at both ends and perforated -with holes, was put into this solution. On the outside of the -copper cylinder there was a copper ring, located below the surface of -the solution, acting as a shelf to support crystals of copper sulphate. -Inside the cylinder there was a porous earthenware jar containing -dilute sulphuric acid and an amalgamated zinc rod. The two liquids -were therefore kept apart but in contact with each other through the -pores of the jar. The hydrogen gas given off by the action of the<span class="pagenum" id="Page_11">11</span> -sulphuric acid on the zinc, combined with the dissolved copper sulphate, -formed sulphuric acid and metallic copper. The latter was -deposited on the copper cylinder which acted as the other electrode. -Thus the copper sulphate acted as a depolarizer.</p> - -<p>The chemical reactions in this cell are,</p> - -<div class="center"><div class="ilb"> -In inner porous jar: Zn + H<sub>2</sub>SO<sub>4</sub> = ZnSO<sub>4</sub> + H<sub>2</sub><br /> -In outer glass jar: H<sub>2</sub> + CuSO<sub>4</sub> = H<sub>2</sub>SO<sub>4</sub> + Cu -</div></div> - -<p>This cell had an open circuit voltage of a little over one volt. Later -the porous cup was dispensed with, the two liquids being kept apart -by the difference of their specific gravities. This was known as the -Gravity cell, and for years was used in telegraphy.</p> - -<div id="i_7" class="figcenter"> - <img src="images/i_011.png" width="959" height="938" style="width: 40%;" alt="" /> - <div class="caption"><p><span class="smcap">Grove’s Cell, 1838.</span></p> - -<p class="justify">This consisted of zinc, sulphuric acid, nitric acid and platinum. -It made a very powerful battery. The nitric acid is called the depolarizer -as it absorbs the hydrogen gas formed, thus improving the operating -voltage.</p></div></div> - -<hr class="chap x-ebookmaker-drop" /> - -<div id="chap_14" class="chapter"> -<h2 class="nobreak" id="GROVES_BATTERY">GROVE’S BATTERY</h2> -</div> - -<p>Sir William Robert Grove, an English Judge and scientist, invented -a cell in 1838 consisting of a platinum electrode in strong nitric acid -in a porous earthenware jar. This jar was put in dilute sulphuric acid -in a glass jar in which there was an amalgamated zinc plate for the -other electrode. This had an open circuit voltage of about 1.9 volts. -The porous jar was used to prevent the nitric acid from attacking the -zinc. The nitric acid was used for the purpose of combining with the<span class="pagenum" id="Page_12">12</span> -hydrogen gas set free by the action of the sulphuric acid on the zinc, -and hence was the depolarizing agent. Hydrogen combining with -nitric acid forms nitrous peroxide and water. Part of the nitrous -peroxide is dissolved in the water, and the rest escapes as fumes -which, however, are very suffocating.</p> - -<p>The chemical equations of this cell are as follows:</p> - -<div class="center"><div class="ilb"> -In outer glass jar: Zn + H<sub>2</sub>SO<sub>4</sub> = ZnSO<sub>4</sub> + H<sub>2</sub><br /> -In inner porous jar: H<sub>2</sub> + 2HNO<sub>3</sub> = N<sub>2</sub>O<sub>4</sub> + 2H<sub>2</sub>O -</div></div> - -<p>An interesting thing about Grove’s cell is that it was planned in -accordance with a theory. Grove knew that the electrical energy of -the zinc-sulphuric acid cell came from the chemical affinity of the two -reagents, and if the hydrogen gas set free could be combined with -oxygen (to form water—H<sub>2</sub>O), such chemical affinity should increase -the strength of the cell. As the hydrogen gas appears at the other -electrode, the oxidizing agent should surround that electrode. Nitric -acid was known at that time as one of the most powerful oxidizing -liquids, but as it attacks copper, he used platinum for the other electrode. -Thus he not only overcame the difficulty of polarization by -the hydrogen gas, but also increased the voltage of the cell by the -added chemical action of the combination of hydrogen and oxygen.</p> - -<hr class="chap x-ebookmaker-drop" /> - -<div id="chap_15" class="chapter"> -<h2 class="nobreak" id="GROVES_DEMONSTRATION_OF_INCANDESCENT_LIGHTING">GROVE’S DEMONSTRATION OF INCANDESCENT LIGHTING</h2> -</div> - -<p>In 1840 Grove made an experimental lamp by attaching the ends -of a coil of platinum wire to copper wires, the lower parts of which -were well varnished for insulation. The platinum wire was covered -by a glass tumbler, the open end set in a glass dish partly filled with -water. This prevented draughts of air from cooling the incandescent -platinum, and the small amount of oxygen of the air in the tumbler -reduced the amount of oxidization of the platinum that would otherwise -occur. With current supplied by a large number of cells of his -battery, he lighted the auditorium of the Royal Institution with these -lamps during one of the lectures he gave. This lamp gave only a -feeble light as there was danger of melting the platinum and platinum -gives but little light unless operated close to its melting temperature. -It also required a lot of current to operate it as the air tended to cool -the incandescent platinum. The demonstration was only of scientific -interest, the cost of current being much too great (estimated at -several hundred dollars a kilowatt hour) to make it commercial.</p> - -<hr class="chap x-ebookmaker-drop" /> - -<div id="chap_16" class="chapter"> -<p><span class="pagenum" id="Page_13">13</span></p> - -<h2 class="nobreak" id="GRENET_BATTERY">GRENET BATTERY</h2> -</div> - -<p>It was discovered that chromic anhydride gives up oxygen easier -than nitric acid and consequently if used would give a higher voltage -than Grove’s nitric acid battery. It also has the advantage of a lesser -tendency to attack zinc directly if it happens to come in contact with it. -Grenet developed a cell having a liquid consisting of a mixture of -potassium bichromate (K<sub>2</sub>Cr<sub>2</sub>O<sub>7</sub>) and sulphuric acid. A porous cell -was therefore not used to keep the two liquids apart. This had the -advantage of reducing the internal resistance. The chemical reaction -was:</p> - -<div class="blockquot hang"> - -<p>K_{2}Cr_{2}O_{7} (potassium bichromate) + 7H_{2}SO_{4} (sulphuric acid) + 3Zn -(zinc) = 3ZnSO<sub>4</sub> (zinc sulphate) + K<sub>2</sub>SO<sub>4</sub> (potassium sulphate) -+ Cr<sub>2</sub> (SO<sub>4</sub>)<sub>3</sub> (chromium sulphate) + 7H<sub>2</sub>O (water).</p> -</div> - -<p>In order to prevent the useless consumption of zinc on open circuit, -the zinc was attached to a sliding rod and could be drawn up into the -neck of the bottle-shaped jar containing the liquid.</p> - -<div id="i_8" class="figcenter"> - <img src="images/i_013.jpg" width="1247" height="830" style="width: 52%;" alt="" /> - <div class="caption"><p><span class="smcap">Grove’s Incandescent Lamp, 1840.</span></p> - -<p>Grove made an experimental lamp, using platinum for the burner -which was protected from draughts of air by a glass tumbler.</p></div></div> - -<hr class="chap x-ebookmaker-drop" /> - -<div id="chap_17" class="chapter"> -<h2 class="nobreak" id="DE_MOLEYNS_INCANDESCENT_LAMP">DE MOLEYNS’ INCANDESCENT LAMP</h2> -</div> - -<p>Frederick De Moleyns, an Englishman, has the honor of having -obtained the first patent on an incandescent lamp. This was in 1841 -and his lamp was quite novel. It consisted of a spherical glass globe, -in the upper part of which was a tube containing powdered charcoal. -This tube was open at the bottom inside the globe and through it ran a<span class="pagenum" id="Page_14">14</span> -platinum wire, the end below the tube being coiled. Another platinum -wire coiled at its upper end came up through the lower part of -the globe but did not quite touch the other platinum coil. The powdered -charcoal filled the two coils of platinum wire and bridged the -gap between. Current passing through this charcoal bridge heated -it to incandescence. The air in the globe having been removed as far -as was possible with the hand air pumps then available, the charcoal -did not immediately burn up, the small amount consumed being replaced -by the supply in the tube. The idea was ingenious but the -lamp was impractical as the globe rapidly blackened from the evaporation -of the incandescent charcoal.</p> - -<div id="i_9" class="figcenter"> - <img src="images/i_014.png" width="722" height="1043" style="width: 30%;" alt="" /> - <div class="caption"><p><span class="smcap">De Moleyns’ Incandescent Lamp, 1841.</span></p> - -<p>This consisted of two coils of platinum wire containing powdered -charcoal operating in a vacuum. It is only of interest as the first -incandescent lamp on which a patent (British) was granted.</p></div></div> - -<hr class="chap x-ebookmaker-drop" /> - -<div id="chap_18" class="chapter"> -<h2 class="nobreak" id="EARLY_DEVELOPMENTS_OF_THE_ARC_LAMP">EARLY DEVELOPMENTS OF THE ARC LAMP</h2> -</div> - -<p>It had been found that most of the light of the arc came from -the tip of the positive electrode, and that the charcoal electrodes were -rapidly consumed, the positive electrode about twice as fast as the -negative. Mechanisms were designed to take care of this, together -with devices to start the arc by allowing the electrodes to touch each -other and then pulling them apart the proper distance. This distance -varied from one-eighth to three-quarters of an inch.</p> - -<p><span class="pagenum" id="Page_15">15</span></p> - -<p>In 1840 Bunsen, the German chemist who invented the bunsen -burner, devised a process for making hard dense carbon pencils which -lasted much longer than the charcoal previously used. The dense -carbon from the inside of the retorts of gas making plants was ground -up and mixed with molasses, moulded into shape and baked at a high -temperature. Bunsen also, in 1843, cheapened Grove’s battery by -substituting a hard carbon plate in place of the platinum electrode.</p> - -<div id="i_10" class="figcenter"> - <img src="images/i_015.png" width="1006" height="1011" style="width: 42%;" alt="" /> - <div class="caption"><p><span class="smcap">Wright’s Arc Lamp, 1845.</span></p> - -<p>This lamp is also only of interest as the first arc lamp on which a -patent (British) was granted. Four arcs played between the five carbon -discs.</p></div></div> - -<p>Thomas Wright, an Englishman, was the first to patent an arc lamp. -This was in 1845, and the lamp was a hand regulated device consisting -of five carbon disks normally touching each other and rotated by clockwork. -Two of the disks could be drawn outward by thumb screws, -which was to be done after the current was turned on thus establishing -four arcs, one between each pair of disks. The next year, 1846, W. E. -Staite, another Englishman, made an arc lamp having two vertical -carbon pencils. The upper was stationary. The lower was movable -and actuated by clockwork directed by ratchets which in turn were -regulated by an electro-magnet controlled by the current flowing -through the arc. Thus the lower carbon would be moved up or down -as required.</p> - -<p>Archereau, a Frenchman, made a very simple arc lamp in 1848. -The upper carbon was fixed and the lower one was mounted on a<span class="pagenum" id="Page_16">16</span> -piece of iron which could be drawn down into a coil of wire. The -weight of the lower electrode was overbalanced by a counterweight, -so that when no current was flowing the two carbons would touch. -When current was turned on, it flowed through the two carbons and -through the coil of wire (solenoid) which then became energized -and pulled the lower carbon down, thus striking the arc. Two of these -arc lamps were installed in Paris and caused considerable excitement. -After a few weeks of unreliable operation, it was found that the cost -of current from the batteries was much too great to continue their -use commercially. The dynamo had not progressed far enough to -permit its use.</p> - -<div id="i_11" class="figcenter"> - <img src="images/i_016.png" width="653" height="996" style="width: 28%;" alt="" /> - <div class="caption"><p><span class="smcap">Archereau’s Arc Lamp, 1848.</span></p> - -<p>This simple arc was controlled by an electro-magnet, and two lamps -were installed for street lighting in Paris, current being obtained from -batteries.</p></div></div> - -<hr class="chap x-ebookmaker-drop" /> - -<div id="chap_19" class="chapter"> -<h2 class="nobreak" id="JOULES_LAW">JOULE’S LAW</h2> -</div> - -<p>Joule was an Englishman, and in 1842 began investigating the -relation between mechanical energy and heat. He first showed that, -by allowing a weight to drop from a considerable height and turn a -paddle wheel in water, the temperature of the water would increase -in relation to the work done in turning the wheel. It is now known -that 778 foot-pounds (1 lb. falling 778 feet, 10 lbs. falling 77.8 feet -or 778 lbs. falling one foot, etc.) is the mechanical equivalent of -energy equal to raising one pound of water one degree Fahrenheit.<span class="pagenum" id="Page_17">17</span> -The rate of energy (power) is the energy divided by a unit of time; -thus one horsepower is 33,000 foot-pounds per minute. Joule next -investigated the relation between heat and electric current. He made -a device consisting of a vessel of water in which there were a thermometer -and an insulated coil of wire having a considerable resistance. -He found that an electric current heated the water, and making many -combinations of the amount and length of time of current flowing -and of the resistance of the wire, he deduced the law that the energy -in an electric circuit is proportional to the square of the amount of -current flowing multiplied by the length of time and multiplied by the -resistance of the wire.</p> - -<p>The rate of electrical energy (electric power) is therefore proportional -to the square of current multiplied by the resistance. The -electrical unit of power is now called the <span class="smcap">Watt</span>, named in honor of -James Watt, the Englishman, who made great improvements to the -steam engine about a century ago. Thus, watts = C<sup>2</sup>R and substituting -the value of R from Ohm’s law, C = E/R, we get</p> - -<p class="center"> -Watts = Volts × Amperes -</p> - -<p>The watt is a small unit of electric power, as can be seen from the -fact that 746 watts are equal to one horsepower. The kilowatt, kilo -being the Greek word for thousand, is 1000 watts.</p> - -<p>This term is an important one in the electrical industry. For -example, dynamos are rated in kilowatts, expressed as KW; the largest -one made so far is 50,000 KW which is 66,666 horsepower. Edison’s -first commercial dynamo had a capacity of 6 KW although the terms -watts and kilowatts were not in use at that time. The ordinary sizes -of incandescent lamps now used in the home are 25, 40 and 50 watts.</p> - -<hr class="chap x-ebookmaker-drop" /> - -<div id="chap_20" class="chapter"> -<h2 class="nobreak" id="STARRS_INCANDESCENT_LAMP">STARR’S INCANDESCENT LAMP</h2> -</div> - -<div id="i_12" class="figcenter"> - <img src="images/i_018.png" width="361" height="1660" style="width: 10%;" alt="" /> - <div class="caption"><p><span class="smcap">Starr’s Incandescent Lamp, 1845.</span></p> - -<p>This consisted of a short carbon pencil operating in the vacuum above -a column of mercury.</p></div></div> - -<p>J. W. Starr, an American, of Cincinnati, Ohio, assisted financially -by Peabody, the philanthropist, went to England where he obtained -a patent in 1845 on the lamps he had invented, although the patent was -taken out under the name of King, his attorney. One is of passing -interest only. It consisted of a strip of platinum, the active length of -which could be adjusted to fit the battery strength used, and was -covered by a glass globe to protect it from draughts of air. The other, -a carbon lamp, was the first real contribution to the art. It consisted -of a rod of carbon operating in the vacuum above a column of mercury -(Torrecellium vacuum) as in a barometer. A heavy platinum wire<span class="pagenum" id="Page_18">18</span> -was sealed in the upper closed end of a large glass tube, and connected -to the carbon rod by an iron clamp. The lower end of the carbon rod -was fastened to another iron clamp, the two clamps being held in -place and insulated from each other by a porcelain rod. Attached to -the lower clamp was a long copper wire. Just below the lower clamp, -the glass tube was narrowed down and had a length of more than -30 inches. The tube was then filled with mercury, the bottom of the -tube being put into a vessel partly full of mercury. The mercury ran -out of the enlarged upper part of the tube, coming to rest in the narrow -part of the tube as in a barometer, so that the carbon rod was then in -a vacuum. One lamp terminal was the platinum wire extending -through the top of the tube, and the other was the mercury. Several<span class="pagenum" id="Page_19">19</span> -of these lamps were put on exhibition in London, but were not a commercial -success as they blackened very rapidly. Starr started his -return trip to the United States the next year, but died on board the -ship when he was but 25 years old.</p> - -<hr class="chap x-ebookmaker-drop" /> - -<div id="chap_21" class="chapter"> -<h2 class="nobreak" id="OTHER_EARLY_INCANDESCENT_LAMPS">OTHER EARLY INCANDESCENT LAMPS</h2> -</div> - -<div id="i_13" class="figcenter"> - <img src="images/i_019a.png" width="607" height="906" style="width: 26%;" alt="" /> - <div class="caption"><p><span class="smcap">Staite’s Incandescent -Lamp, 1848.</span></p> - -<p>The burner was of platinum -and iridium.</p></div></div> - -<div id="i_14" class="figcenter"> - <img src="images/i_019b.png" width="595" height="1026" style="width: 26%;" alt="" /> - <div class="caption"><p><span class="smcap">Roberts’ Incandescent -Lamp, 1852.</span></p> - -<p>It had a graphite burner operating -in vacuum.</p></div></div> - -<p>In 1848 W. E. Staite, who two years previously had made an arc -lamp, invented an incandescent lamp. This consisted of a platinum-iridium -burner in the shape of an inverted U, covered by a glass globe. -It had a thumb screw for a switch, the whole device being mounted -on a bracket which was used for the return wire. E. C. Shepard, -another Englishman, obtained a patent two years later on an incandescent -lamp consisting of a weighted hollow charcoal cylinder the -end of which pressed against a charcoal cone. Current passing -through this high resistance contact, heated the charcoal to incandescence. -It operated in a glass globe from which the air could be exhausted. -M. J. Roberts obtained an English patent in 1852 on an -incandescent lamp. This had a graphite rod for a burner, which -could be renewed, mounted in a glass globe. The globe was cemented -to a metallic cap fastened to a piece of pipe through which the air<span class="pagenum" id="Page_20">20</span> -could be exhausted. After being exhausted, the pipe, having a stop -cock, could be screwed on a stand to support the lamp.</p> - -<p>Moses G. Farmer, a professor at the Naval Training Station at -Newport, Rhode Island, lighted the parlor of his home at 11 Pearl -Street, Salem, Mass., during July, 1859, with several incandescent -lamps having a strip of platinum for the burner. The novel feature -of this lamp was that the platinum strip was narrower at the terminals -than in the center. Heat is conducted away from the terminals -and by making the burner thin at these points, the greater resistance -of the ends of the burner absorbed more electrical energy thus offsetting -the heat being conducted away. This made a more uniform -degree of incandescence throughout the length of the burner, and -Prof. Farmer obtained a patent on this principle many years later -(1882).</p> - -<div id="i_15" class="figcenter"> - <img src="images/i_020.png" width="1371" height="936" style="width: 58%;" alt="" /> - <div class="caption"><p><span class="smcap">Farmer’s Incandescent Lamp, 1859.</span></p> - -<p>This experimental platinum lamp was made by Professor Farmer -and several of them lighted the parlor of his home in Salem, -Mass.</p></div></div> - -<hr class="chap x-ebookmaker-drop" /> - -<div id="chap_22" class="chapter"> -<h2 class="nobreak" id="FURTHER_ARC_LAMP_DEVELOPMENTS">FURTHER ARC LAMP DEVELOPMENTS</h2> -</div> - -<p>During the ten years, 1850 to 1860, several inventors developed -arc lamp mechanisms. Among them was M. J. Roberts, who had -invented the graphite incandescent lamp. In Roberts’ arc lamp, -which he patented in 1852, the lower carbon was stationary. The -upper carbon fitted snugly into an iron tube. In the tube was a brass -covered iron rod, which by its weight could push the upper carbon<span class="pagenum" id="Page_21">21</span> -down the tube so the two carbons normally were in contact. An -electro-magnet in series with the arc was so located that, when energized, -it pulled up the iron tube. This magnet also held the brass -covered iron rod from pushing the upper carbon down the tube so that -the two carbons were pulled apart, striking the arc. When the arc -went out, the iron tube dropped back into its original position, the -brass covered iron rod was released, pushing the upper carbon down -the tube until the two carbons again touched. This closed the circuit -again, striking the arc as before.</p> - -<div id="i_16" class="figcenter"> - <img src="images/i_021a.png" width="647" height="1020" style="width: 28%;" alt="" /> - <div class="caption"><p><span class="smcap">Roberts’ Arc Lamp, -1852.</span></p> - -<p>The arc was controlled by an -electro-magnet which held an -iron tube to which the upper -carbon was fastened.</p></div></div> - -<div id="i_17" class="figcenter"> - <img src="images/i_021b.png" width="525" height="1020" style="width: 22%;" alt="" /> - <div class="caption"><p><span class="smcap">Slater and Watson’s Arc -Lamp, 1852.</span></p> - -<p>Clutches were used for the -first time in this arc lamp to -feed the carbons.</p></div></div> - -<p>In the same year (1852) Slater and Watson obtained an English -patent on an arc lamp in which the upper carbon was movable and -held in place by two clutches actuated by electro-magnets. The lower -carbon was fixed, and normally the two carbons touched each other. -When current was turned on, the electro-magnet lifted the clutches -which gripped the upper carbon, pulling it up and striking the arc. -This was the first time that a clutch was used to allow the carbon to -feed as it became consumed.</p> - -<p>Henry Chapman, in 1855, made an arc in which the upper carbon -was allowed to feed by gravity, but held in place by a chain wound<span class="pagenum" id="Page_22">22</span> -around a wheel. On this wheel was a brake actuated by an electro-magnet. -The lower carbon was pulled down by an electro-magnet -working against a spring. When no current was flowing or when the -arc went out, the two carbons touched. With current on, one electro-magnet -set the brake and held the upper carbon stationary. The other -electro-magnet pulled the lower carbon down, thus striking the arc.</p> - -<p>None of these mechanisms regulated the length of the arc. It was -not until 1856 that Joseph Lacassagne and Henry Thiers, Frenchmen, -invented the so-called “differential” method of control, which made -the carbons feed when the arc voltage, and hence length, became too -great. This principle was used in commercial arc lamps several -years afterward when they were operated on series circuits, as it had -the added advantage of preventing the feeding of one arc lamp affecting -another on the same circuit. This differential control consists in -principle of two electro-magnets, one in series with, and opposing -the pull of the other which is in shunt with the arc. The series magnet -pulls the carbons apart and strikes the arc. As the arc increases in -length, its voltage rises, thereby increasing the current flowing through -the shunt magnet. This increases the strength of the shunt magnet -and, when the arc becomes too long, the strength of the shunt becomes -greater than that of the series magnet, thus making the carbons -feed.</p> - -<div id="i_18" class="figcenter"> - <img src="images/i_022.png" width="1603" height="644" style="width: 68%;" alt="" /> - <div class="caption"><p><span class="smcap">Diagram of “Differential” Method of Control of an Arc Lamp.</span></p> - -<p>This principle, invented by Lacassagne and Thiers, was used in all -arc lamps when they were commercially introduced on a large scale -more than twenty years later.</p></div></div> - -<p>The actual method adopted by Lacassagne and Thiers was different -from this, but it had this principle. They used a column of mercury -on which the lower carbon floated. The upper carbon was stationary. -The height of the mercury column was regulated by a valve connected<span class="pagenum" id="Page_23">23</span> -with a reservoir of mercury. The pull of the series magnet -closed the valve fixing the height of the column. The pull of the -shunt magnet tended to open the valve, and when it overcame the -pull of the series magnet it allowed mercury to flow from the reservoir, -raising the height of the column bringing the carbons nearer -together. This reduced the arc voltage and shunt magnet strength -until the valve closed again. Thus the carbons were always kept the -proper distance apart. In first starting the arc, or if the arc should -go out, current would only flow through the shunt magnet, bringing -the two carbons together until they touched. Current would then -flow through the contact of the two carbons and through the series -magnet, shutting the valve. There were no means of pulling the -carbons apart to strike the arc. Current flowing through the high -resistance of the poor contact of the two carbons, heated their tips -to incandescence. The incandescent tips would begin to burn away, -thus after a time starting an arc. The arc, however, once started was -maintained the proper length.</p> - -<div id="i_19" class="figcenter"> - <img src="images/i_023.png" width="491" height="1229" style="width: 22%;" alt="" /> - <div class="caption"><p><span class="smcap">Lacassagne and Thiers’ Differentially Controlled -Arc Lamp, 1856.</span></p> - -<p>The lower carbon floated on a column of mercury whose height was -“differentially” controlled by series and shunt magnets.</p></div></div> - -<p><span class="pagenum" id="Page_24">24</span></p> - -<p>In 1857, Serrin took out his first patent on an arc lamp, the general -principles of which were the same as in others he made. The mechanism -consisted of two drums, one double the diameter of the other. -Both carbons were movable, the upper one feeding down, and the -lower one feeding up, being connected with chains wound around -the drums. The difference in consumption of the two carbons was -therefore compensated for by the difference in size of the drums, -thus maintaining the location of the arc in a fixed position. A train -of wheels controlled by a pawl and regulated by an electro-magnet, -controlled the movement of the carbons. The weight of the upper -carbon and its holder actuates the train of wheels.</p> - -<div id="i_20" class="figcenter"> - <img src="images/i_024.png" width="457" height="1030" style="width: 20%;" alt="" /> - <div class="caption"><p><span class="smcap">Serrin’s Arc Lamp, 1857.</span></p> - -<p class="justify">This type of arc was not differentially controlled but was the first -commercial lamp later used. Both carbons were movable, held by -chains wound around drums which were controlled by ratchets actuated -by an electro-magnet.</p></div></div> - -<hr class="chap x-ebookmaker-drop" /> - -<div id="chap_23" class="chapter"> -<h2 class="nobreak" id="DEVELOPMENT_OF_THE_DYNAMO_18401860">DEVELOPMENT OF THE DYNAMO, 1840–1860</h2> -</div> - -<p>During the first few years after 1840 the dynamo was only a laboratory -experiment. Woolrich devised a machine which had several -pairs of magnets and double the number of coils in order to make -the current obtained less pulsating. Wheatstone in 1845 patented -the use of electro-magnets in place of permanent magnets. Brett in -1848 suggested that the current, generated in the coils, be allowed to<span class="pagenum" id="Page_25">25</span> -flow through a coil surrounding each permanent magnet to further -strengthen the magnets. Pulvermacher in 1849 proposed the use of -thin plates of iron for the bobbins, to reduce the eddy currents generated -in the iron. Sinsteden in 1851 suggested that the current from -a permanent magnet machine be used to excite the field coils of an -electro-magnet machine.</p> - -<p>In 1855 Soren Hjorth, of Copenhagen, Denmark, patented a -dynamo having both permanent and electro-magnets, the latter being -excited by currents first induced in the bobbins by the permanent -magnets. In 1856 Dr. Werner Siemens invented the shuttle wound -armature. This consisted of a single coil of wire wound lengthwise -and counter sunk in a long cylindrical piece of iron. This revolved -between the magnet poles which were shaped to fit the cylindrical -armature.</p> - -<div id="i_21" class="figcenter"> - <img src="images/i_025.png" width="1141" height="1224" style="width: 48%;" alt="" /> - <div class="caption"><p><span class="smcap">Siemens’ Dynamo, 1856.</span></p> - -<p>This dynamo was an improvement over others on account of the -construction of its “shuttle” armature.</p></div></div> - -<hr class="chap x-ebookmaker-drop" /> - -<div id="chap_24" class="chapter"> -<h2 class="nobreak" id="THE_FIRST_COMMERCIAL_INSTALLATION_OF_AN_ELECTRIC_LIGHT">THE FIRST COMMERCIAL INSTALLATION OF AN ELECTRIC LIGHT</h2> -</div> - -<p>In 1862 a Serrin type of arc lamp was installed in the Dungeness -lighthouse in England. Current was supplied by a dynamo made by<span class="pagenum" id="Page_26">26</span> -the Alliance Company, which had been originally designed in 1850 -by Nollet, a professor of Physics in the Military School in Brussels. -Nollet’s original design was of a dynamo having several rows of permanent -magnets mounted radially on a stationary frame, with an -equal number of bobbins mounted on a shaft which rotated and had a -commutator so direct current could be obtained. A company was -formed to sell hydrogen gas for illuminating purposes, the gas to be -made by the decomposition of water with current from this machine. -Nollet died and the company failed, but it was reorganized as the -Alliance Company a few years later to exploit the arc lamp.</p> - -<div id="i_22" class="figcenter"> - <img src="images/i_026.jpg" width="1173" height="1097" style="width: 50%;" alt="" /> - <div class="caption"><p><span class="smcap">Alliance Dynamo, 1862.</span></p> - -<p>This was the dynamo used in the first commercial installation of an -arc light in the Dungeness Lighthouse, England, 1862.</p></div></div> - -<p>About the only change made in the dynamo was to substitute collector -rings for the commutator to overcome the difficulties of commutation. -Alternating current was therefore generated in this first -commercial machine. It had a capacity for but one arc light, which -probably consumed less than ten amperes at about 45 volts, hence -delivered in the present terminology not over 450 watts or about -two-thirds of a horsepower. As the bobbins of the armature undoubtedly -had a considerable resistance, the machine had an efficiency -of not over 50 per cent and therefore required at least one and a -quarter horsepower to drive it.</p> - -<hr class="chap x-ebookmaker-drop" /> - -<div id="chap_25" class="chapter"> -<p><span class="pagenum" id="Page_27">27</span></p> - -<h2 class="nobreak" id="FURTHER_DYNAMO_DEVELOPMENTS">FURTHER DYNAMO DEVELOPMENTS</h2> -</div> - -<p>In the summer of 1886 Sir Charles Wheatstone constructed a self-excited -machine on the principle of using the residual magnetism in -the field poles to set up a feeble current in the armature which, -passing through the field coils, gradually strengthened the fields until -they built up to normal strength. It was later found that this idea -had been thought of by an unknown man, being disclosed by a clause -in a provisional 1858 English patent taken out by his agent. Wheatstone’s -machine was shown to the Royal Society in London and a -paper on it read before the Society on February 14, 1867. The field -coils were shunt wound.</p> - -<div id="i_23" class="figcenter"> - <img src="images/i_027.jpg" width="1361" height="1064" style="width: 58%;" alt="" /> - <div class="caption"><p><span class="smcap">Wheatstone’s Self-Excited Dynamo, 1866.</span></p> - -<p>This machine was the first self-excited dynamo by use of the residual -magnetism in the field poles.</p></div></div> - -<p>Dr. Werner Siemens also made a self-excited machine, having -series fields, a paper on which was read before the Academy of -Sciences in Berlin on January 17, 1867. This paper was forwarded -to the Royal Society in London and presented at the same meeting -at which Wheatstone’s dynamo was described. Wheatstone probably -preceded Siemens in this re-discovery of the principle of self-excitation, -but both are given the merit of it. However, S. A. Varley on -December 24, 1866, obtained a provisional English patent on this, -which was not published until July, 1867.</p> - -<p><span class="pagenum" id="Page_28">28</span></p> - -<div id="i_24" class="figcenter"> - <img src="images/i_028a.jpg" width="1538" height="1238" style="width: 64%;" alt="" /> - <div class="caption"><p><span class="smcap">Gramme’s Dynamo, 1871.</span></p> - -<p>These were commercially used, their main feature being the “ring” -wound armature.</p></div></div> - -<div id="i_25" class="figcenter"> - <img src="images/i_028b.png" width="948" height="828" style="width: 40%;" alt="" /> - <div class="caption"><p><span class="smcap">Gramme’s “Ring” Armature.</span></p> - -<p>Wire coils, surrounding an iron wire core, were all connected -together in an endless ring, each coil being tapped with a wire connected -to a commutator bar.</p></div></div> - -<p><span class="pagenum" id="Page_29">29</span></p> - -<p>In 1870 Gramme, a Frenchman, patented his well-known ring -armature. The idea had been previously thought of by Elias, a -Hollander, in 1842, and by Pacinnotti, an Italian, as shown by the -crude motors (not dynamos) they had made. Gramme’s armature -consisted of an iron wire core coated with a bituminous compound -in order to reduce the eddy currents. This core was wound with -insulated wire coils, all connected together in series as one single -endless coil. Each coil was tapped with a wire connected to a commutator -bar. His first machine, having permanent magnets for fields, -was submitted to the French Academy of Sciences in 1871. Later -machines were made with self-excited field coils, which were used in -commercial service. They had, however a high resistance armature, -so that their efficiency did not exceed 50 per cent.</p> - -<div id="i_26" class="figcenter"> - <img src="images/i_029.jpg" width="1629" height="1218" style="width: 68%;" alt="" /> - <div class="caption"><p><span class="smcap">Alteneck’s Dynamo with “Drum” Wound Armature, 1872.</span></p> - -<p>The armature winding was entirely on the surface of the armature -core, a principle now used in all dynamos.</p></div></div> - -<p>Von Hefner Alteneck, an engineer with Siemens, invented the -drum wound armature in 1872. The wires of the armature were all -on the surface of the armature core, the wires being tapped at frequent -points for connection with the commutator bars. Thus in the early -seventies, commercial dynamos were available for use in arc lighting, -and a few installations were made in Europe.</p> - -<hr class="chap x-ebookmaker-drop" /> - -<div id="chap_26" class="chapter"> -<p><span class="pagenum" id="Page_30">30</span></p> - -<h2 class="nobreak" id="RUSSIAN_INCANDESCENT_LAMP_INVENTORS">RUSSIAN INCANDESCENT LAMP INVENTORS</h2> -</div> - -<p>In 1872 Lodyguine, a Russian scientist, made an incandescent lamp -consisting of a “V” shaped piece of graphite for a burner, which -operated in nitrogen gas. He lighted the Admiralty Dockyard at -St. Petersburg with about two hundred of these lamps. In 1872 -the Russian Academy of Sciences awarded him a prize of 50,000 -rubles (a lot of real money at that time) for his invention. A company -with a capital of 200,000 rubles (then equal to about $100,000) -was formed but as the lamp was so expensive to operate and had such -a short life, about twelve hours, the project failed.</p> - -<div id="i_27" class="figcenter"> - <img src="images/i_030a.png" width="468" height="825" style="width: 20%;" alt="" /> - <div class="caption"><p><span class="smcap">Lodyguine’s Incandescent -Lamp, 1872.</span></p> - -<p>The burner was made of -graphite and operated in nitrogen -gas.</p></div></div> - -<div id="i_28" class="figcenter"> - <img src="images/i_030b.png" width="563" height="1237" style="width: 24%;" alt="" /> - <div class="caption"><p><span class="smcap">Konn’s Incandescent Lamp, -1875.</span></p> - -<p>In this lamp the graphite rods -operated in a vacuum.</p></div></div> - -<p>Kosloff, another Russian, in 1875 patented a graphite in nitrogen -incandescent lamp, which had several graphite rods for burners, so -arranged that when one failed another was automatically connected. -Konn, also a Russian, made a lamp similar to Kosloff’s except that -the graphite rods operated in a vacuum. Bouliguine, another Russian, -in 1876 made an incandescent lamp having a long graphite rod, only<span class="pagenum" id="Page_31">31</span> -the upper part of which was in circuit. As this part burned out, the -rod was automatically pushed up so that a fresh portion then was in -circuit. It operated in a vacuum. None of these lamps was commercial -as they blackened rapidly and were too expensive to maintain.</p> - -<div id="i_29" class="figcenter"> - <img src="images/i_031.png" width="736" height="1646" style="width: 32%;" alt="" /> - <div class="caption"><p><span class="smcap">Bouliguine’s Incandescent Lamp, 1876.</span></p> - -<p>A long graphite rod, the upper part of which only was in circuit, -operated in vacuum. As this part burned out, the rod was automatically -shoved up, a fresh portion then being in the circuit.</p></div></div> - -<hr class="chap x-ebookmaker-drop" /> - -<div id="chap_27" class="chapter"> -<h2 class="nobreak" id="THE_JABLOCHKOFF_CANDLE">THE JABLOCHKOFF “CANDLE”</h2> -</div> - -<p>Paul Jablochkoff was a Russian army officer and an engineer. In -the early seventies he came to Paris and developed a novel arc light. -This consisted of a pair of carbons held together side by side and -insulated from each other by a mineral known as kaolin which vaporized -as the carbons were consumed. There was no mechanism, the<span class="pagenum" id="Page_32">32</span> -arc being started by a thin piece of carbon across the tips of the carbons. -Current burned this bridge, starting the arc. The early carbons -were about five inches long, and the positive carbon was twice as -thick as the negative to compensate for the unequal consumption on -direct current. This, however, did not work satisfactorily. Later -the length of the carbons was increased, the carbon made of equal -thickness and burned on alternating current of about eight or nine -amperes at about 45 volts. He made an alternating current generator -which had a stationary exterior armature with interior revolving field -poles. Several “candles,” as they were called, were put in one fixture -to permit all night service and an automatic device was developed, -located in each fixture, so that should one “candle” go out for any -reason, another was switched into service.</p> - -<div id="i_30" class="figcenter"> - <img src="images/i_032.png" width="691" height="1236" style="width: 30%;" alt="" /> - <div class="caption"><p><span class="smcap">Jablochkoff “Candle,” 1876.</span></p> - -<p class="justify">This simple arc consisted of a pair of carbons held together side by -side and insulated from each other by kaolin. Several boulevards in -Paris were lighted with these arc lights. This arc lamp is in the -collection of the Smithsonian Institution.</p></div></div> - -<p>In 1876 many of these “candles” were installed and later several -of the boulevards in Paris were lighted with them. This was the<span class="pagenum" id="Page_33">33</span> -first large installation of the arc light, and was the beginning of its -commercial introduction. Henry Wilde made some improvements -in the candle by eliminating the kaolin between the carbons which -gave Jablochkoff’s arc its peculiar color. Wilde’s arc was started by -allowing the ends of the carbons to touch each other, a magnet swinging -them apart thus striking the arc.</p> - -<div id="i_31" class="figcenter"> - <img src="images/i_033.jpg" width="1059" height="1042" style="width: 44%;" alt="" /> - <div class="caption"><p><span class="smcap">Jablochkoff’s Alternating Current Dynamo, 1876.</span></p> - -<p class="justify">This dynamo had a stationary exterior armature and internal revolving -field poles. Alternating current was used for the Jablochkoff -“candle” to overcome the difficulties of unequal consumption of the -carbons on direct current.</p></div></div> - -<hr class="chap x-ebookmaker-drop" /> - -<div id="chap_28" class="chapter"> -<h2 class="nobreak" id="COMMERCIAL_INTRODUCTION_OF_THE_DIFFERENTIALLY">COMMERCIAL INTRODUCTION OF THE DIFFERENTIALLY CONTROLLED -ARC LAMP</h2> -</div> - -<p>About the same time Lontin, a Frenchman, improved Serrin’s arc -lamp mechanism by the application of series and shunt magnets. This -is the differential principle which was invented by Lacassagne and -Thiers in 1855 but which apparently had been forgotten. Several -of these lamps were commercially installed in France beginning with -1876.</p> - -<hr class="chap x-ebookmaker-drop" /> - -<div id="chap_29" class="chapter"> -<h2 class="nobreak" id="ARC_LIGHTING_IN_THE_UNITED_STATES">ARC LIGHTING IN THE UNITED STATES</h2> -</div> - -<div id="i_32" class="figcenter"> - <img src="images/i_034a.png" width="1087" height="1227" style="width: 46%;" alt="" /> - <div class="caption"><p><span class="smcap">Wallace-Farmer Arc Lamp, 1875.</span></p> - -<p class="justify">This “differentially controlled” arc lamp consisted of two slabs of -carbon between which the arc played. In the original lamp the carbon -slabs were mounted on pieces of wood held in place by bolts, -adjustment being made by hitting the upper carbon slab with a hammer. -This lamp is in the collection of the Smithsonian Institution.</p></div></div> - -<div id="i_33" class="figcenter"> - <img src="images/i_034b.jpg" width="1604" height="1031" style="width: 68%;" alt="" /> - <div class="caption"><p><span class="smcap">Wallace-Farmer Dynamo, 1875.</span></p> - -<p>This was the first commercial dynamo used in the United States for -arc lighting. This dynamo is in the collection of the Smithsonian -Institution.</p></div></div> - -<p>About 1875 William Wallace of Ansonia, Connecticut, made an -arc light consisting of two rectangular carbon plates mounted on -a wooden frame. The arc played between the two edges of the plates,<span class="pagenum" id="Page_35">35</span> -which lasted much longer than rods. When the edges had burned -away so that the arc then became unduly long, the carbon plates were -brought closer together by hitting them with a hammer. Wallace -became associated with Moses G. Farmer, and they improved this -crude arc by fastening the upper carbon plate to a rod which was held -by a clutch controlled by a magnet. This magnet had two coils in one, -the inner winding in series with the arc, and outer one in shunt and -opposing the series winding. The arc was therefore differentially -controlled.</p> - -<div id="i_34" class="figcenter"> - <img src="images/i_035.png" width="866" height="1219" style="width: 36%;" alt="" /> - <div class="caption"><p><span class="smcap">Weston’s Arc Lamp, 1876.</span></p> - -<p>This lamp is in the collection of the Smithsonian Institution.</p></div></div> - -<p>They also developed a series wound direct current dynamo. -The armature consisted of a number of bobbins, all connected -together in an endless ring. Each bobbin was also connected to -a commutator bar. There were two sets of bobbins, commutators and -field poles, the equivalent of two machines in one, which could be -connected either to separate circuits, or together in series on one -circuit. The Wallace-Farmer system was commercially used. The -arc consumed about 20 amperes at about 35 volts, but as the carbon -plates cooled the arc, the efficiency was poor. The arc flickered back -and forth on the edges of the carbons casting dancing shadows. The<span class="pagenum" id="Page_36">36</span> -carbons, while lasting about 50 hours, were not uniform in density, -so the arc would flare up and cast off soot and sparks.</p> - -<p>Edward Weston of Newark, New Jersey, also developed an arc -lighting system. His commercial lamp had carbon rods, one above the -other, and the arc was also differentially controlled. An oil dash pot -prevented undue pumping of the carbons. His dynamo had a drum-wound -armature, and had several horizontal field coils on each side of -one pair of poles between which the armature revolved. The system -was designed for about 20 amperes, each are taking about 35 volts.</p> - -<div id="i_35" class="figcenter"> - <img src="images/i_036a.png" width="1173" height="549" style="width: 50%;" alt="" /> - <div class="caption"><p><span class="smcap">Brush’s Dynamo, 1877.</span></p> - -<p>This dynamo was used for many years for commercial arc lighting.</p></div></div> - -<div id="i_36" class="figcenter"> - <img src="images/i_036b.png" width="793" height="821" style="width: 34%;" alt="" /> - <div class="caption"><p><span class="smcap">Diagram of Brush Armature.</span></p> - -<p>The armature was not a closed circuit. For description of its operation, -see text.</p></div></div> - -<p>Charles F. Brush made a very successful arc lighting system in -1878. His dynamo was unique in that the armature had eight coils,<span class="pagenum" id="Page_37">37</span> -one end of each pair of opposite coils being connected together and -the other ends connected to a commutator segment. Thus the armature -itself was not a closed circuit. The machine had two pairs of -horizontal poles between which the coils revolved. One end of the -one pair of coils in the most active position was connected, by means -of two of the four brushes, in series with one end of the two pairs -of coils in the lesser active position. The latter two pairs of coils -were connected in multiple with each other by means of the brushes -touching adjacent commutator segments. The outside circuit was -connected to the other two brushes, one of which was connected to -the other end of the most active pair of coils. The other brush was -connected to the other end of the two lesser active pairs of coils. The -one pair of coils in the least active position was out of circuit. The -field coils were connected in series with the outside circuit.</p> - -<div id="i_37" class="figcenter"> - <img src="images/i_037.png" width="531" height="1206" style="width: 22%;" alt="" /> - <div class="caption"><p><span class="smcap">Brush’s Arc Lamp, 1877.</span></p> - -<p>The carbons were differentially controlled. This lamp was used -for many years. This lamp is in the collection of the Smithsonian -Institution.</p></div></div> - -<p>Brush’s arc lamp was also differentially controlled. It was designed -for about 10 amperes at about 45 volts. The carbons were -copper plated to increase their conductivity. Two pairs of carbons -were used for all-night service, each pair lasting about eight hours.<span class="pagenum" id="Page_38">38</span> -A very simple device was used to automatically switch the arc from -one to the other pair of carbons, when the first pair was consumed. -This device consisted of a triangular-shaped piece of iron connected -to the solenoid controlling the arc. There was a groove on each of the -outer two corners of this triangle, one groove wider than the other. -An iron washer surrounded each upper carbon. The edge of each -washer rested in a groove. The washer in the narrow groove made a -comparatively tight fit about its carbon. The other washer in the -wider groove had a loose fit about its carbon. Pins prevented the -washer from falling below given points. Both pairs of carbons -touched each other at the start. When current was turned on, the -solenoid lifted the triangle, the loose-fitting washer gripped its carbon -first, so that current then only passed through the other pair of carbons -which were still touching each other. The further movement of the -solenoid then separated these carbons, the arc starting between them. -When this pair of carbons became consumed, they could not feed any -more so that the solenoid would then allow the other pair of carbons -to touch, transferring the arc to that pair.</p> - -<div id="i_38" class="figcenter"> - <img src="images/i_038.jpg" width="1486" height="1002" style="width: 62%;" alt="" /> - <div class="caption"><p><span class="smcap">Thomson-Houston Arc Dynamo, 1878.</span></p> - -<p>This dynamo was standard for many years. This machine is in the -collection of the Smithsonian Institution.</p></div></div> - -<p>Elihu Thomson and Edwin J. Houston in 1878 made a very successful -and complete arc light system. Their dynamo was specially<span class="pagenum" id="Page_39">39</span> -designed to fit the requirements of the series arc lamp. The Thomson-Houston -machine was a bipolar, having an armature consisting of -three coils, one end of each of the three coils having a common terminal, -or “Y” connected, as it is called. The other end of each coil -was connected to a commutator segment. The machine was to a great -extent self-regulating, that is the current was inherently constant with -fluctuating load, as occurs when the lamps feed or when the number -of lamps burning at one time should change for any reason. This -regulation was accomplished by what is called “armature reaction,” -which is the effect the magnetization of the armature has on the field -strength. Close regulation was obtained by a separate electro-magnet, -in series with the circuit, which shifted the brushes as the load -changed. As there were but three commutator segments, one for each -coil, excessive sparking was prevented by an air blast.</p> - -<div id="i_39" class="figcenter"> - <img src="images/i_039.png" width="1465" height="796" style="width: 62%;" alt="" /> - <div class="caption"><span class="smcap">Diagram of T-H Arc Lighting System.</span></div></div> - -<p>The “T-H” (Thompson-Houston) lamp employed the shunt feed -principle. The carbons were normally separated, being in most types -drawn apart by a spring. A high resistance magnet, shunted around -the arc, served to draw the carbons together. This occurred on -starting the lamp and thereafter the voltage of the arc was held constant -by the balance between the spring and the shunt magnet. As -the carbon burned away the mechanism advanced to a point where -a clutch was tripped, the carbons brought together, and the cycle repeated. -Both the T-H and Brush systems were extensively used in -street lighting, for which they were the standard when the open arc -was superseded by the enclosed.</p> - -<hr class="chap x-ebookmaker-drop" /> - -<div id="chap_30" class="chapter"> -<p><span class="pagenum" id="Page_40">40</span></p> - -<h2 class="nobreak" id="OTHER_AMERICAN_ARC_LIGHT_SYSTEMS">OTHER AMERICAN ARC LIGHT SYSTEMS</h2> -</div> - -<div id="i_40" class="figcenter"> - <img src="images/i_040a.jpg" width="962" height="1834" style="width: 40%;" alt="" /> - <div class="caption"><p><span class="smcap">Thomson-Houston Arc -Lamp, 1878.</span></p> - -<p>This is an early model with a single -pair of carbons.</p></div></div> - -<div id="i_41" class="figcenter"> - <img src="images/i_040b.png" width="284" height="1839" style="width: 12%;" alt="" /> - <div class="caption"><p><span class="smcap">Thomson Double -Carbon Arc Lamp.</span></p> - -<p>This later model, -having two pairs of -carbons, was commercially -used for many -years. This lamp is -in the collection of -the Smithsonian Institution.</p></div></div> - -<p>Beginning with about 1880, several arc light systems were developed. -Among these were the Vanderpoele, Hochausen, Waterhouse, Maxim, -Schuyler and Wood. The direct current carbon arc is inherently more -efficient than the alternating current lamp, owing to the fact that the -continuous flow of current in one direction maintains on the positive<span class="pagenum" id="Page_41">41</span> -carbon a larger crater at the vaporizing point of carbon. This source -furnishes the largest proportion of light, the smaller crater in the -negative carbon much less. With the alternating current arc, the -large crater is formed first on the upper and then on the lower carbon. -On account of the cooling between alternations, the mean temperature -falls below the vaporizing point of carbon, thus accounting for the -lower efficiency of the alternating current arc.</p> - -<div id="i_42" class="figcenter"> - <img src="images/i_041.jpg" width="1124" height="1252" style="width: 48%;" alt="" /> - <div class="caption"><p><span class="smcap">Maxim Dynamo.</span></p> - -<p>This dynamo is in the collection of the Smithsonian Institution.</p></div></div> - -<p>For this reason all these systems used direct current and the 10 -ampere ultimately displaced the 20 ampere system. The 10 ampere -circuit was later standardized at 9.6 amperes, 50 volts per lamp. The -lamp therefore consumed 480 watts giving an efficiency of about 15 -lumens per watt. This lamp gave an average of 575 candlepower -(spherical) in all directions, though it was called the 2000 cp (candlepower) -arc as under the best possible conditions it could give this -candlepower in one direction. Later a 6.6 ampere arc was developed. -This was called the “1200 cp” lamp and was not quite as efficient as -the 9.6 ampere lamp.</p> - -<hr class="chap x-ebookmaker-drop" /> - -<div id="chap_31" class="chapter"> -<p><span class="pagenum" id="Page_42">42</span></p> - -<h2 class="nobreak" id="SUB-DIVIDING_THE_ELECTRIC_LIGHT">“SUB-DIVIDING THE ELECTRIC LIGHT”</h2> -</div> - -<p>While the arc lamp was being commercially established, it was at -once seen that it was too large a unit for household use. Many inventors -attacked the problem of making a smaller unit, or, as it was -called, “sub-dividing the electric light.” In the United States there -were four men prominent in this work: William E. Sawyer, Moses G. -Farmer, Hiram S. Maxim and Thomas A. Edison. These men did -not make smaller arc lamps but all attempted to make an incandescent -lamp that would operate on the arc circuits.</p> - -<div id="i_43" class="figcenter"> - <img src="images/i_042a.png" width="329" height="1007" style="width: 14%;" alt="" /> - <div class="caption"><p><span class="smcap">Sawyer’s Incandescent -Lamp, 1878.</span></p> - -<p>This had a graphite burner -operating in nitrogen gas.</p></div></div> - -<div id="i_44" class="figcenter"> - <img src="images/i_042b.png" width="384" height="1024" style="width: 16%;" alt="" /> - <div class="caption"><p><span class="smcap">Farmer’s Incandescent -Lamp, 1878.</span></p> - -<p>The graphite burner operated -in nitrogen gas. This -lamp is in the collection of the -Smithsonian Institution.</p></div></div> - -<p>Sawyer made several lamps in the years 1878–79 along the lines of -the Russian scientists. All his lamps had a thick carbon burner -operating in nitrogen gas. They had a long glass tube closed at one -end and the other cemented to a brass base through which the gas -was put in. Heavy fluted wires connected the burner with the base -to radiate the heat, in order to keep the joint in the base cool. The -burner was renewable by opening the cemented joint. Farmer’s lamp -consisted of a pair of heavy copper rods mounted on a rubber cork, -between which a graphite rod was mounted. This was inserted in -a glass bulb and operated in nitrogen gas. Maxim made a lamp -having a carbon burner operating in a rarefied hydrocarbon vapor. -He also made a lamp consisting of a sheet of platinum operating in air.</p> - -<hr class="chap x-ebookmaker-drop" /> - -<div id="chap_32" class="chapter"> -<p><span class="pagenum" id="Page_43">43</span></p> - -<h2 class="nobreak" id="EDISONS_INVENTION_OF_A_PRACTICAL_INCANDESCENT_LAMP">EDISON’S INVENTION OF A PRACTICAL INCANDESCENT LAMP</h2> -</div> - -<p>Edison began the study of the problem in the spring of 1878. He -had a well-equipped laboratory at Menlo Park, New Jersey, with -several able assistants and a number of workmen, about a hundred -people all told. He had made a number of well-known inventions, -among which were the quadruplex telegraph whereby four messages -could be sent simultaneously over one wire, the carbon telephone -transmitter without which Bell’s telephone receiver would have been -impracticable, and the phonograph. All of these are in use today, so -Edison was eminently fitted to attack the problem.</p> - -<div id="i_45" class="figcenter"> - <img src="images/i_043.png" width="1354" height="1211" style="width: 56%;" alt="" /> - <div class="caption"><p><span class="smcap">Maxim’s Incandescent Lamp, 1878.</span></p> - -<p>The carbon burner operated in a rarefied hydrocarbon vapor. This -lamp is in the collection of the Smithsonian Institution.</p></div></div> - -<p>Edison’s first experiments were to confirm the failures of other -experimenters. Convinced of the seeming impossibility of carbon, -he turned his attention to platinum as a light giving element. Realizing -the importance of operating platinum close to its melting temperature, -he designed a lamp which had a thermostatic arrangement so -that the burner would be automatically short circuited the moment its -temperature became dangerously close to melting. The burner consisted -of a double helix of platinum wire within which was a rod.<span class="pagenum" id="Page_44">44</span> -When the temperature of the platinum became too high, the rod in -expanding would short circuit the platinum. The platinum cooled -at once, the rod contracted opening the short circuit and allowing -current to flow through the burner again. His first incandescent lamp -patent covered this lamp. His next patent covered a similar lamp with -an improved thermostat consisting of an expanding diaphragm. Both -of these lamps were designed for use on series circuits.</p> - -<div id="i_46" class="figcenter"> - <img src="images/i_044.png" width="1504" height="1212" style="width: 64%;" alt="" /> - <div class="caption"><p><span class="smcap">Edison’s First Experimental Lamp, 1878.</span></p> - -<p>The burner was a coil of platinum wire which was protected from -operating at too high a temperature by a thermostat.</p></div></div> - -<p>The only system of distributing electricity, known at that time, -was the series system. In this system current generated in the dynamo -armature flowed through the field coils, out to one lamp after another -over a wire, and then back to the dynamo. There were no means -by which one lamp could be turned on and off without doing the same -with all the others on the circuit. Edison realized that while this was -satisfactory for street lighting where arcs were generally used, it never -would be commercial for household lighting. He therefore decided -that a practical incandescent electric lighting system must be patterned -after gas lighting with which it would compete. He therefore made<span class="pagenum" id="Page_45">45</span> -an intensive study of gas distribution and reasoned that a constant -pressure electrical system could be made similar to that of gas.</p> - -<p>The first problem was therefore to design a dynamo that would -give a constant pressure instead of constant current. He therefore -reasoned that the internal resistance of the armature must be very -low or the voltage would fall as current was taken from the dynamo. -Scientists had shown that the most economical use of electricity from -a primary battery was where the external resistance of the load was -the same as the internal resistance of the battery, or in other words, -50 per cent was the maximum possible efficiency.</p> - -<div id="i_47" class="figcenter"> - <img src="images/i_045a.png" width="1413" height="516" style="width: 60%;" alt="" /> - <div class="caption"><p><span class="smcap">Diagram of Constant Current Series System.</span></p> - -<p>This, in 1878, was the only method of distributing electric current.</p></div></div> - -<div id="i_48" class="figcenter"> - <img src="images/i_045b.png" width="1468" height="417" style="width: 62%;" alt="" /> - <div class="caption"><p><span class="smcap">Diagram of Edison’s Multiple System, 1879.</span></p> - -<p>Edison invented the multiple system of distributing electric current, -now universally used.</p></div></div> - -<p>When Edison proposed a very low resistance armature so that the -dynamo would have an efficiency of 90 per cent at full load, he was -ridiculed. Nevertheless he went ahead and made one which attained -this. The armature consisted of drum-wound insulated copper rods, -the armature core having circular sheets of iron with paper between -to reduce the eddy currents. There were two vertical fields above and<span class="pagenum" id="Page_46">46</span> -connected in shunt with the armature. It generated electricity at about -a hundred volts constant pressure and could supply current up to about -60 amperes at this pressure. It therefore had a capacity, in the -present terminology, of about 6 kilowatts (or 8 horsepower).</p> - -<div id="i_49" class="figcenter"> - <img src="images/i_046.png" width="911" height="1209" style="width: 38%;" alt="" /> - <div class="caption"><p><span class="smcap">Edison Dynamo, 1879.</span></p> - -<p class="justify">Edison made a dynamo that was 90 per cent efficient which scientists -said was impossible. This dynamo is in the collection of the Smithsonian -Institution and was one of the machines on the steamship -Columbia, the first commercial installation of the Edison lamp.</p></div></div> - -<p>A multiple system of distribution would make each lamp independent -of every other and with a dynamo made for such a system, the -next thing was to design a lamp for it. Having a pressure of about -a hundred volts to contend with, the lamp, in order to take a small -amount of current, must, to comply with Ohm’s law, have a high -resistance. He therefore wound many feet of fine platinum wire on -a spool of pipe clay and made his first high resistance lamp. He used -his diaphragm thermostat to protect the platinum from melting, and, -as now seems obvious but was not to all so-called electricians at that -time, the thermostat was arranged to open circuit instead of short -circuit the burner when it became too hot. This lamp apparently -solved the problem, and, in order to protect the platinum from the<span class="pagenum" id="Page_47">47</span> -oxygen of the air, he coated it with oxide of zirconium. Unfortunately -zirconia, while an insulator at ordinary temperatures, becomes, -as is now known, a conductor of electricity when heated, so that the -lamp short circuited itself when it was lighted.</p> - -<div id="i_50" class="figcenter"> - <img src="images/i_047a.png" width="707" height="1616" style="width: 30%;" alt="" /> - <div class="caption"><p><span class="smcap">Edison’s High Resistance -Platinum Lamp, 1879.</span></p> - -<p>This lamp had a high resistance -burner, necessary for the -multiple system.</p></div></div> - -<div id="i_51" class="figcenter"> - <img src="images/i_047b.png" width="620" height="1610" style="width: 26%;" alt="" /> - <div class="caption"><p><span class="smcap">Edison’s High Resistance -Platinum in Vacuum -Lamp, 1879.</span></p> - -<p>This experimental lamp led -to the invention of the successful -carbon filament lamp.</p></div></div> - -<p>During his experiments he had found that platinum became exceedingly -hard after it had been heated several times to incandescence -by current flowing through it. This apparently raised its melting -temperature so he was able to increase the operating temperature -and therefore greatly increase the candlepower of his lamps after<span class="pagenum" id="Page_48">48</span> -they had been heated a few times. Examination of the platinum -under a microscope showed it to be much less porous after heating, -so he reasoned that gases were occluded throughout the platinum -and were driven out by the heat. This led him to make a lamp with -a platinum wire to operate in vacuum, as he thought that more of the -occluded gases would come out under such circumstances.</p> - -<div id="i_52" class="figcenter"> - <img src="images/i_048.png" width="477" height="913" style="width: 20%;" alt="" /> - <div class="caption"><p><span class="smcap">Edison’s Carbon Lamp of October 21, 1879.</span></p> - -<p class="justify">This experimental lamp, having a high resistance carbon filament -operating in a high vacuum maintained by an all-glass globe, was -the keystone of Edison’s successful incandescent lighting system. All -incandescent lamps made today embody the basic features of this -lamp. This replica is in the Smithsonian Institution exhibit of Edison -lamps. The original was destroyed.</p></div></div> - -<p>These lamps were expensive to make, and, knowing that he could -get the requisite high resistance at much less cost from a long and -slender piece of carbon, he thought he might be able to make the carbon -last in the high vacuum he had been able to obtain from the newly -invented Geissler and Sprengel mercury air pumps. After several -trials he finally was able to carbonize a piece of ordinary sewing thread. -This he mounted in a one-piece all glass globe, all joints fused by melting -the glass together, which he considered was essential in order to -maintain the high vacuum. Platinum wires were fused in the glass to -connect the carbonized thread inside the bulb with the circuit outside -as platinum has the same coefficient of expansion as glass and hence -maintains an airtight joint. He reasoned that there would be occluded -gases in the carbonized thread which would immediately burn<span class="pagenum" id="Page_49">49</span> -up if the slightest trace of oxygen were present, so he heated the -lamp while it was still on the exhaust pump after a high degree of -vacuum had been obtained. This was accomplished by passing a -small amount of current through the “filament,” as he called it, gently -heating it. Immediately the gases started coming out, and it took eight -hours more on the pump before they stopped. The lamp was then -sealed and ready for trial.</p> - -<div id="i_53" class="figcenter"> - <img src="images/i_049.jpg" width="1611" height="801" style="width: 68%;" alt="" /> - <div class="caption"><p><span class="smcap">Demonstration of Edison’s Incandescent Lighting System.</span></p> - -<p>Showing view of Menlo Park Laboratory Buildings, 1880.</p></div></div> - -<p>On October 21, 1879, current was turned into the lamp and it -lasted forty-five hours before it failed. A patent was applied for -on November 4th of that year and granted January 27, 1880. All -incandescent lamps made today embody the basic features of this -lamp. Edison immediately began a searching investigation of the best -material for a filament and soon found that carbonized paper gave -several hundred hours life. This made it commercially possible, so -in December, 1879, it was decided that a public demonstration of his -incandescent lighting system should be made. Wires were run to -several houses in Menlo Park, N. J., and lamps were also mounted on -poles, lighting the country roads in the neighborhood. An article -appeared in the New York Herald on Sunday, December 21, 1879, -describing Edison’s invention and telling of the public demonstration -to be given during the Christmas holidays. This occupied the entire -first page of the paper, and created such a furor that the Pennsylvania -Railroad had to run special trains to Menlo Park to accommodate<span class="pagenum" id="Page_50">50</span> -the crowds. The first commercially successful installation of the -Edison incandescent lamps and lighting system was made on the -steamship Columbia, which started May 2, 1880, on a voyage around -Cape Horn to San Francisco, Calif.</p> - -<p>The carbonized paper filament of the first commercial incandescent -lamp was quite fragile. Early in 1880 carbonized bamboo was found -to be not only sturdy but made an even better filament than paper. -The shape of the bulb was also changed from round to pear shape, -being blown from one inch tubing. Later the bulbs were blown -directly from molten glass.</p> - -<div id="i_54" class="figcenter"> - <img src="images/i_050.jpg" width="1375" height="1011" style="width: 58%;" alt="" /> - <div class="caption"><p><span class="smcap">Dynamo Room, S. S. Columbia.</span></p> - -<p>The first commercial installation of the Edison Lamp, started -May 2, 1880. One of these original dynamos is on exhibit at the -Smithsonian Institution.</p></div></div> - -<p>As it was inconvenient to connect the wires to the binding posts of -a new lamp every time a burned out lamp had to be replaced, a base -and socket for it were developed. The earliest form of base consisted -simply of bending the two wires of the lamp back on the neck -of the bulb and holding them in place by wrapping string around -the neck. The socket consisted of two pieces of sheet copper in a -hollow piece of wood. The lamp was inserted in this, the two-wire -terminals of the lamp making contact with the two-sheet copper -terminals of the socket, the lamp being rigidly held in the socket by<span class="pagenum" id="Page_51">51</span> -a thumb screw which forced the socket terminals tight against the -neck of the bulb.</p> - -<div id="i_55" class="figcenter"> - <img src="images/i_051a.png" width="960" height="625" style="width: 40%;" alt="" /> - <div class="caption"><span class="smcap">Original Socket for Incandescent Lamps, 1880.</span></div></div> - -<div id="i_56" class="figcenter"> - <img src="images/i_051b.png" width="237" height="807" style="width: 10%;" alt="" /> - <div class="caption"><p><span class="smcap">Wire Terminal Base Lamp, 1880.</span></p> - -<p>This crude form of lamp base fitted the original form of lamp -socket pictured above. This lamp is in the exhibit of Edison lamps -in the Smithsonian Institution.</p></div></div> - -<p>This crude arrangement was changed in the latter part of 1880 to -a screw shell and a ring for the base terminals, wood being used for -insulation. The socket was correspondingly changed. This was a -very bulky affair, so the base was changed to a cone-shaped ring and -a screw shell for terminals. Wood was used for insulation, which -a short time after was changed to plaster of Paris as this was also -used to fasten the base to the bulb. It was soon found that the tension -created between the two terminals of the base when the lamp was<span class="pagenum" id="Page_52">52</span> -firmly screwed in the socket often caused the plaster base to pull apart, -so the shape of the base was again changed early in 1881, to the form -in use today.</p> - -<p>An improved method of connecting the ends of the filament to the -leading-in wires was adopted early in 1881. Formerly this was -accomplished by a delicate clamp having a bolt and nut. The improvement -consisted of copper plating the filament to the leading-in wire.</p> - -<div id="i_57" class="figcenter"> - <img src="images/i_052a.png" width="271" height="821" style="width: 12%;" alt="" /> - <div class="caption"><p><span class="smcap">Original Screw Base -Lamp, 1880.</span></p> - -<p>This first screw base, consisting -of a screw shell and -ring for terminals with wood -for insulation, was a very -bulky affair. This lamp is in -the exhibit of Edison lamps in -the Smithsonian Institution.</p></div></div> - -<div id="i_58" class="figcenter"> - <img src="images/i_052b.png" width="288" height="817" style="width: 12%;" alt="" /> - <div class="caption"><p><span class="smcap">Improved Screw Base -Lamp, 1881.</span></p> - -<p class="justify">The terminals of this base -consisted of a cone shaped ring -and a screw shell. At first -wood was used for insulation, -later plaster of paris which -was also used to fasten the -base to the bulb. This lamp -is in the exhibit of Edison -lamps in the Smithsonian Institution.</p></div></div> - -<p>In the early part of the year 1881 the lamps were made “eight to -the horsepower.” Each lamp, therefore, consumed a little less than -100 watts, and was designed to give 16 candlepower in a horizontal -direction. The average candlepower (spherical) in all directions was -about 77 per cent of this, hence as the modern term “lumen” is 12.57 -spherical candlepower, these lamps had an initial efficiency of about -1.7 lumens per watt. The lamps blackened considerably during their -life so that just before they burned out their candlepower was less -than half that when new. Thus their mean efficiency throughout life -was about 1.1 l-p-w (lumens per watt). These figures are interesting<span class="pagenum" id="Page_53">53</span> -in comparison with the modern 100-watt gas-filled tungsten-filament -lamp which has an initial efficiency of 12.9, and a mean efficiency of -11.8, l-p-w. In other words the equivalent (wattage) size of modern -lamp gives over seven times when new, and eleven times on the -average, as much light for the same energy consumption as Edison’s -first commercial lamp. In the latter part of 1881 the efficiency was -changed to “ten lamps per horsepower,” equivalent to 2¼ l-p-w -initially. Two sizes of lamps were made: 16 cp for use on 110-volt -circuits and 8 cp for use either direct on 55 volts or two in series on -110-volt circuits.</p> - -<div id="i_59" class="figcenter"> - <img src="images/i_053.png" width="315" height="810" style="width: 14%;" alt="" /> - <div class="caption"><p><span class="smcap">Final Form of Screw Base, 1881.</span></p> - -<p class="justify">With plaster of paris, the previous form of base was apt to pull -apart when the lamp was firmly screwed into the socket. The form -of the base was therefore changed to that shown, which overcame -these difficulties, and which has been used ever since. The lamp -shown was standard for three years and is in the exhibit of Edison -lamps in the Smithsonian Institution.</p></div></div> - -<hr class="chap x-ebookmaker-drop" /> - -<div id="chap_33" class="chapter"> -<h2 class="nobreak" id="EDISONS_THREE-WIRE_SYSTEM">EDISON’S THREE-WIRE SYSTEM</h2> -</div> - -<p>The distance at which current can be economically delivered at -110 volts pressure is limited, as will be seen from a study of Ohm’s -law. The loss of power in the distributing wires is proportional to -the square of the current flowing. If the voltage be doubled, the -amount of current is halved, for a given amount of electric power -delivered, so that the size of the distributing wires can then be reduced -to one-quarter for a given loss in them. At that time (1881) it was<span class="pagenum" id="Page_54">54</span> -impossible to make 220-volt lamps, and though they are now available, -their use is uneconomical, as their efficiency is much poorer than that -of 110-volt incandescent lamps.</p> - -<p>Edison invented a distributing system that had two 110-volt circuits, -with one wire called the neutral, common to both circuits so that the -pressure on the two outside wires was 220 volts. The neutral wire -had only to be large enough to carry the difference between the currents -flowing in the two circuits. As the load could be so arranged -that it would be approximately equal at all times on both circuits, -the neutral wire could be relatively small in size. Thus the three-wire -system resulted in a saving of 60 per cent in copper over the two-wire -system or, for the same amount of copper, the distance that current -could be delivered was more than doubled.</p> - -<div id="i_60" class="figcenter"> - <img src="images/i_054.png" width="1386" height="829" style="width: 58%;" alt="" /> - <div class="caption"><p><span class="smcap">Diagram of Edison’s Three-Wire System, 1881.</span></p> - -<p>This system reduced the cost of copper in the multiple distributing -system 60 per cent.</p></div></div> - -<hr class="chap x-ebookmaker-drop" /> - -<div id="chap_34" class="chapter"> -<h2 class="nobreak" id="DEVELOPMENT_OF_THE_ALTERNATING_CURRENT">DEVELOPMENT OF THE ALTERNATING CURRENT CONSTANT -POTENTIAL SYSTEM</h2> -</div> - -<p>The distance that current can be economically distributed, as has -been shown, depends upon the voltage used. If, therefore, current -could be sent out at a high voltage and the pressure brought down to -that desired at the various points to which it is distributed, such distribution -could cover a much greater area. Lucien Gaulard was a -French inventor and was backed by an Englishman named John D. -Gibbs. About 1882 they patented a series alternating-current system -of distribution. They had invented what is now called a transformer -which consisted of two separate coils of wire mounted on an iron<span class="pagenum" id="Page_55">55</span> -core. All the primary coils were connected in series, which, when -current went through them, induced a current in the secondary coils. -Lamps were connected in multiple on each of the secondary coils. -An American patent was applied for on the transformer, but was -refused on the basis that “more current cannot be taken from it than -is put in.” While this is true if the word energy were used, the -transformer can supply a greater current at a lower voltage (or vice -versa) than is put in, the ratio being in proportion to the relative -number of turns in the primary and secondary coils. The transformer -was treated with ridicule and Gaulard died under distressing circumstances.</p> - -<div id="i_61" class="figcenter"> - <img src="images/i_055.png" width="1573" height="822" style="width: 66%;" alt="" /> - <div class="caption"><p><span class="smcap">Diagram of Stanley’s Alternating Current Multiple -System, 1885.</span></p> - -<p>This system is now universally used for distributing electric current -long distances.</p></div></div> - -<p>Information regarding the transformer came to the attention of -William Stanley, an American, in the latter part of 1885. He made -an intensive study of the scheme, and developed a transformer in which -the primary coil was connected in multiple on a constant potential -alternating-current high-voltage system. From the secondary coil a -lower constant voltage was obtained. An experimental installation -was made at Great Barrington, Mass., in the early part of 1886, the -first commercial installation being made in Buffalo, New York, in -the latter part of the year. This scheme enabled current to be economically -distributed to much greater distances. The voltage of the -high-tension circuit has been gradually increased as the art has progressed -from about a thousand volts to over two hundred thousand -volts pressure in a recent installation in California, where electric -power is transmitted over two hundred miles.</p> - -<hr class="chap x-ebookmaker-drop" /> - -<div id="chap_35" class="chapter"> -<p><span class="pagenum" id="Page_56">56</span></p> - -<h2 class="nobreak" id="INCANDESCENT_LAMP_DEVELOPMENTS_18841894">INCANDESCENT LAMP DEVELOPMENTS, 1884–1894</h2> -</div> - -<p>In 1884 the ring of plaster around the top of the base was omitted; -in 1886 an improvement was made by pasting the filament to the -leading-in wires with a carbon paste instead of the electro-plating -method; and in 1888 the length of the base was increased so that it -had more threads. Several concerns started making incandescent -lamps, the filaments being made by carbonizing various substances. -“Parchmentized” thread consisted of ordinary thread passed through -sulphuric acid. “Tamadine” was cellulose in the sheet form, punched -out in the shape of the filament. Squirted cellulose in the form of a -thread was also used. This was made by dissolving absorbent cotton -in zinc chloride, the resulting syrup being squirted through a die into -alcohol which hardened the thread thus formed. This thread was -washed in water, dried in the air and then cut to proper length and -carbonized.</p> - -<div id="i_62" class="figcenter"> - <img src="images/i_056a.png" width="347" height="837" style="width: 16%;" alt="" /> - <div class="caption"><p><span class="smcap">Standard Edison Lamp, 1884.</span></p> - -<p>The ring of plaster around -the neck of previous lamps was -omitted. This lamp is in the -exhibit of Edison lamps in the -Smithsonian Institution.</p></div></div> - -<div id="i_63" class="figcenter"> - <img src="images/i_056b.png" width="377" height="814" style="width: 16%;" alt="" /> - <div class="caption"><p><span class="smcap">Standard Edison Lamp, 1888.</span></p> - -<p>The length of the base was -increased so it had more -threads. This lamp is in the -exhibit of Edison lamps in the -Smithsonian Institution.</p></div></div> - -<p>The filament was improved by coating it with graphite. One -method, adopted about 1888, was to dip it in a hydrocarbon liquid -before carbonizing. Another, more generally adopted in 1893 was a -process originally invented by Sawyer, one of the Americans who had -attempted to “sub-divide the electric light” in 1878–79. This process<span class="pagenum" id="Page_57">57</span> -consisted of passing current through a carbonized filament in an -atmosphere of hydrocarbon vapor. The hot filament decomposed the -vapor, depositing graphite on the filament. The graphite coated filament -improved it so it could operate at 3½ lumens per watt (initial efficiency). -Lamps of 20, 24, 32 and 50 candlepower were developed for -110-volt circuits. Lamps in various sizes from 12 to 36 cp were made -for use on storage batteries having various numbers of cells and giving -a voltage of from 20 to 40 volts. Miniature lamps of from ½ to 2 cp -for use on dry batteries of from 2½ to 5½ volts, and 3 to 6 cp on -5½ to 12 volts, were also made. These could also be connected in -series on 110 volts for festoons. Very small lamps of ½ cp of 2 to -4 volts for use in dentistry and surgery were made available. These -miniature lamps had no bases, wires being used to connect them to -the circuit.</p> - -<div id="i_64" class="figcenter"> - <img src="images/i_057.png" width="367" height="817" style="width: 16%;" alt="" /> - <div class="caption"><p><span class="smcap">Standard Edison Lamp, 1894.</span></p> - -<p class="justify">This lamp had a “treated” cellulose filament, permitting an efficiency -of 3½ lumens per watt which has never been exceeded in a -carbon lamp. This lamp is in the exhibit of Edison lamps in the -Smithsonian Institution.</p></div></div> - -<p>Lamps for 220-volt circuits were developed as this voltage was -desirable for power purposes, electric motors being used, and a few -lamps were needed on such circuits. They are less efficient and more -expensive than 110-volt lamps, their use being justified however -only when it is uneconomical to have a separate 110-volt circuit for -lighting. The lamps were made in sizes from 16 to 50 candlepower.</p> - -<p><span class="pagenum" id="Page_58">58</span></p> - -<div id="i_65" class="figcenter smaller b4"> -<div class="figilb four"> - <img src="images/i_058a1.png" width="415" height="680" alt="" /> - <div class="caption">Edison.</div></div> -<div class="figilb four"> - <img src="images/i_058a2.png" width="415" height="680" alt="" /> - <div class="caption">Thomson-Houston.</div></div> -<div class="figilb four"> - <img src="images/i_058a3.png" width="415" height="680" alt="" /> - <div class="caption">Westinghouse.</div></div> -<div class="figilb four"> - <img src="images/i_058a4.png" width="415" height="680" alt="" /> - <div class="caption">Brush-Swan.</div></div> - -<div class="figilb clear four"> - <img src="images/i_058b1.png" width="415" height="680" alt="" /> - <div class="caption">Edi-Swan<br />(single contact).</div></div> -<div class="figilb four"> - <img src="images/i_058b2.png" width="415" height="680" alt="" /> - <div class="caption">Edi-Swan<br />(double contact).</div></div> -<div class="figilb four"> - <img src="images/i_058b3.png" width="415" height="680" alt="" /> - <div class="caption">United States.</div></div> -<div class="figilb four"> - <img src="images/i_058b4.png" width="415" height="680" alt="" /> - <div class="caption">Hawkeye.</div></div> - -<div class="figilb clear three"> - <img src="images/i_058c1.png" width="533" height="680" alt="" /> - <div class="caption">Ft. Wayne Jenny.</div></div> -<div class="figilb three"> - <img src="images/i_058c2.png" width="533" height="680" alt="" /> - <div class="caption">Mather or Perkins.</div></div> -<div class="figilb three"> - <img src="images/i_058c3.png" width="533" height="680" alt="" /> - <div class="caption">Loomis.</div></div> - -<div class="figilb clear three"> - <img src="images/i_058d1.png" width="533" height="680" alt="" /> - <div class="caption">Schaeffer or National.</div></div> -<div class="figilb three"> - <img src="images/i_058d2.png" width="533" height="680" alt="" /> - <div class="caption">Indianapolis Jenny.</div></div> -<div class="figilb three"> - <img src="images/i_058d3.png" width="533" height="680" alt="" /> - <div class="caption">Siemens & Halske.</div></div> - -<p class="clear p1 center larger"><span class="smcap">Various Standard Bases in Use, 1892.</span></p> -</div> - -<p><span class="pagenum" id="Page_59">59</span></p> - -<div id="i_66" class="figcenter"> - <img src="images/i_059a.jpg" width="1447" height="753" style="width: 60%;" alt="" /> - <div class="caption"><span class="smcap">Thomson-Houston Socket.</span></div></div> - -<div id="i_67" class="figcenter"> - <img src="images/i_059b.jpg" width="1361" height="987" style="width: 58%;" alt="" /> - <div class="caption"><span class="smcap">Westinghouse Socket.</span></div></div> - -<p><span class="pagenum" id="Page_60">60</span></p> - -<p>Electric street railway systems used a voltage in the neighborhood -of 550, and lamps were designed to burn five in series on this voltage. -These lamps were different from the standard 110-volt lamps although -they were made for about this voltage. As they were burned in series, -the lamps were selected to operate at a definite current instead of at -a definite voltage, so that the lamps when burned in series would -operate at the proper temperature to give proper life results. Such -lamps would therefore vary considerably in individual volts, and -hence would not give good service if burned on 110-volt circuits. -The candelabra screw base and socket and the miniature screw base -and socket were later developed. Ornamental candelabra base lamps -were made for use direct on 110 volts, smaller sizes being operated -in series on this voltage. The former gave about 10 cp, the latter in -various sizes from 4 to 8 cp. The miniature screw base lamps were -for low volt lighting.</p> - -<div id="i_68" class="figcenter"> - <img src="images/i_060.png" width="1106" height="614" style="width: 46%;" alt="" /> - <div class="caption"> - -<p class="p0"> -Thomson-Houston.<span class="in4">Westinghouse.</span> -</p> - -<p><span class="smcap">Adapters for Edison Screw Sockets, 1892.</span></p> - -<p>Next to the Edison base, the Thomson-Houston and Westinghouse -bases were the most popular. By use of these adapters, Edison base -lamps could be used in T-H and Westinghouse sockets.</p></div></div> - -<p>The various manufacturers of lamps in nearly every instance made -bases that were very different from one another. No less than fourteen -different standard bases and sockets came into commercial use. -These were known as, Brush-Swan, Edison, Edi-Swan (double contact), -Edi-Swan (single contact), Fort Wayne Jenny, Hawkeye, -Indianapolis Jenny, Loomis, Mather or Perkins, Schaeffer or National, -Siemens & Halske, Thomson-Houston, United States and -Westinghouse. In addition there were later larger sized bases made<span class="pagenum" id="Page_61">61</span> -for use on series circuits. These were called the Bernstein, Heisler, -Large Edison, Municipal Bernstein, Municipal Edison, Thomson-Houston -(alternating circuit) and Thomson-Houston (arc circuit). -Some of these bases disappeared from use and in 1900 the proportion -in the United States was about 70 per cent Edison, 15 per cent Westinghouse, -10 per cent Thomson-Houston and 5 per cent for all the -others remaining. A campaign was started to standardize the Edison -base, adapters being sold at cost for the Westinghouse and Thomson-Houston -sockets so that Edison base lamps could be used. In a few -years the desired results were obtained so that now there are no other -sockets in the United States but the Edison screw type for standard<span class="pagenum" id="Page_62">62</span> -lighting service. This applies also to all other countries in the world -except England where the bayonet form of base and socket is still -popular.</p> - -<div id="i_69" class="figcenter smaller"> -<div class="figilb three"> - <img src="images/i_061a1.png" width="504" height="685" alt="" /> - <div class="caption">Bernstein.</div></div> -<div class="figilb three"> - <img src="images/i_061a2.png" width="504" height="685" alt="" /> - <div class="caption">Heisler.</div></div> -<div class="figilb three"> - <img src="images/i_061a3.png" width="504" height="685" alt="" /> - <div class="caption">Thomson-Houston<br />(alternating current).</div></div> - -<div class="figilb three clear"> - <img src="images/i_061b1.png" width="504" height="685" alt="" /> - <div class="caption">Thomson-Houston<br />(arc circuit).</div></div> -<div class="figilb three"> - <img src="images/i_061b2.png" width="504" height="685" alt="" /> - <div class="caption">Municipal Edison.</div></div> -<div class="figilb three"> - <img src="images/i_061b3.png" width="504" height="685" alt="" /> - <div class="caption">Municipal Bernstein.</div></div> - -<p class="clear p1 center larger"><span class="smcap">Various Series Bases in Use, 1892.</span></p> - -<p class="center">The above six bases have been superseded by the “Large Edison,” -now called the Mogul Screw base.</p> -</div> - -<hr class="chap x-ebookmaker-drop" /> - -<div id="chap_36" class="chapter"> -<h2 class="nobreak" id="THE_EDISON_MUNICIPAL_STREET_LIGHTING_SYSTEM">THE EDISON “MUNICIPAL” STREET LIGHTING SYSTEM</h2> -</div> - -<div id="i_70" class="figcenter"> - <img src="images/i_062.jpg" width="1645" height="1096" style="width: 68%;" alt="" /> - <div class="caption"><p><span class="smcap">Edison “Municipal” System, 1885.</span></p> - -<p class="justify">High voltage direct current was generated, several circuits operating -in multiple, three ampere lamps burning in series on each circuit. -Photograph courtesy of Association of Edison Illuminating Companies.</p></div></div> - -<p>The arc lamp could not practically be made in a unit smaller than -the so-called “1200 candlepower” (6.6 ampere) or “half” size, -which really gave about 350 spherical candlepower. A demand therefore -arose for a small street lighting unit, and Edison designed his -“Municipal” street lighting system to fill this requirement. His -experience in the making of dynamos enabled him to make a direct -current bipolar constant potential machine that would deliver 1000 -volts which later was increased to 1200 volts. They were first made -in two sizes having an output of 12 and 30 amperes respectively. -Incandescent lamps were made for 3 amperes in several sizes from -16 to 50 candlepower. These lamps were burned in series on the -1200-volt direct current system. Thus the 12-ampere machine had -a capacity for four series circuits, each taking 3 amperes, the series<span class="pagenum" id="Page_63">63</span> -circuits being connected in multiple across the 1200 volts. The -number of lamps on each series circuit depended upon their size, as -the voltage of each lamp was different for each size, being about 1½ -volts per cp.</p> - -<p>A popular size was the 32-candlepower unit, which therefore -required about 45 volts and hence at 3 amperes consumed about 135 -watts. Allowing 5 per cent loss in the wires of each circuit, there -was therefore 1140 of the 1200 volts left for the lamps. Hence -about 25 32-candlepower or 50 16-candlepower lamps could be put on -each series circuit. Different sizes of lamps could also be put on the -same circuit, the number depending upon the aggregate voltage of the -lamps.</p> - -<div id="i_71" class="figcenter"> - <img src="images/i_063.png" width="379" height="816" style="width: 16%;" alt="" /> - <div class="caption"><p><span class="smcap">Edison Municipal Lamp, 1885.</span></p> - -<p>Inside the base was an arrangement by which the lamp was automatically -short circuited when it burned out.</p></div></div> - -<p>A device was put in the base of each lamp to short circuit the lamp -when it burned out so as to prevent all the other lamps on that circuit -from going out. This device consisted of a piece of wire put inside -the lamp bulb between the two ends of the filament. Connected to -this wire was a very thin wire inside the base which held a piece of -metal compressed against a spring. The spring was connected to one -terminal of the base. Should the lamp burn out, current would jump -from the filament to the wire in the bulb, and the current then flowed -through the thin wire to the other terminal of the base. The thin -wire was melted by the current, and the spring pushed the piece of -metal up short circuiting the terminals of the base. This scheme was<span class="pagenum" id="Page_64">64</span> -later simplified by omitting the wire, spring, etc., and substituting a -piece of metal which was prevented from short circuiting the terminals -of the base by a thin piece of paper. When the lamp burned -out the entire 1200 volts was impressed across this piece of paper, -puncturing it and so short circuiting the base terminals. Should one -or more lamps go out on a circuit, the increase in current above the -normal 3 amperes was prevented by an adjustable resistance, or an -extra lot of lamps which could be turned on one at a time, connected -to each circuit and located in the power station under the control of -the operator. This system disappeared from use with the advent of -the constant current transformer.</p> - -<hr class="chap x-ebookmaker-drop" /> - -<div id="chap_37" class="chapter"> -<h2 class="nobreak" id="THE_SHUNT_BOX_SYSTEM_FOR_SERIES_INCANDESCENT_LAMPS">THE SHUNT BOX SYSTEM FOR SERIES INCANDESCENT LAMPS</h2> -</div> - -<div id="i_72" class="figcenter"> - <img src="images/i_064.png" width="1653" height="420" style="width: 70%;" alt="" /> - <div class="caption"><p><span class="smcap">Shunt Box System, 1887.</span></p> - -<p>Lamps were burned in series on a high voltage alternating current, -and when a lamp burned out all the current then went through its -“shunt box,” a reactance coil in multiple with each lamp.</p></div></div> - -<p>Soon after the commercial development of the alternating current -constant potential system, a scheme was developed to permit the use -of lamps in series on such circuits without the necessity for short -circuiting a lamp should it burn out. A reactance, called a “shunt -box” and consisting of a coil of wire wound on an iron core, was -connected across each lamp. The shunt box consumed but little -current while the lamp was burning. Should one lamp go out, the -entire current would flow through its shunt box and so maintain the -current approximately constant. It had the difficulty, however, that -if several lamps went out, the current would be materially increased -tending to burn out the remaining lamps on the circuit. This system -also disappeared from use with the development of the constant -current transformer.</p> - -<hr class="chap x-ebookmaker-drop" /> - -<div id="chap_38" class="chapter"> -<p><span class="pagenum" id="Page_65">65</span></p> - -<h2 class="nobreak" id="THE_ENCLOSED_ARC_LAMP">THE ENCLOSED ARC LAMP</h2> -</div> - -<p>Up to 1893 the carbons of an arc lamp operated in the open air, -so that they were rapidly consumed, lasting from eight to sixteen -hours depending on their length and thickness. Louis B. Marks, an -American, found that by placing a tight fitting globe about the arc, -the life of the carbons was increased ten to twelve times. This was -due to the restricted amount of oxygen of the air in the presence of -the hot carbon tips and thus retarded their consumption. The amount -of light was somewhat decreased, but this was more than offset by -the lesser expense of trimming which also justified the use of more -expensive better quality carbons. Satisfactory operation required -that the arc voltage be increased to about 80 volts.</p> - -<div id="i_73" class="figcenter"> - <img src="images/i_065.jpg" width="1073" height="1220" style="width: 46%;" alt="" /> - <div class="caption"><p><span class="smcap">Enclosed Arc Lamp, 1893.</span></p> - -<p>Enclosing the arc lengthened the life of the carbons, thereby greatly -reducing the cost of maintenance.</p></div></div> - -<p>This lamp rapidly displaced the series open arc. An enclosed arc -lamp for use on 110-volt constant potential circuits was also developed. -A resistance was put in series with the arc for use on 110-volt direct -current circuits, to act as a ballast in order to prevent the arc from -taking too much current and also to use up the difference between the<span class="pagenum" id="Page_66">66</span> -arc voltage (80) and the line voltage (110). On alternating current, -a reactance was used in place of the resistance.</p> - -<p>The efficiencies in lumens per watt of these arcs (with clear glassware), -all of which have now disappeared from the market, were -about as follows:</p> - -<p class="in0"> -6.6 ampere 510 watt direct current (D.C.) series arc, 8¼ l-p-w.<br /> -5.0 ampere 550 watt direct current multiple (110-volt) arc, 4½ l-p-w.<br /> -7.5 ampere 540 watt alternating current (A.C.) multiple (110-volt) arc, 4¼ l-p-w. -</p> - -<div id="i_74" class="figcenter"> - <img src="images/i_066a.png" width="446" height="1270" style="width: 20%;" alt="" /> - <div class="caption"><p><span class="smcap">Open Flame Arc -Lamp, 1898.</span></p> - -<p>Certain salts impregnated in -the carbons produced a brilliantly -luminous flame in the -arc stream which enormously -increased the efficiency of the -lamp.</p></div></div> - -<div id="i_75" class="figcenter"> - <img src="images/i_066b.png" width="587" height="1436" style="width: 26%;" alt="" /> - <div class="caption"><p><span class="smcap">Enclosed Flame Arc -Lamp, 1908.</span></p> - -<p>By condensing the smoke -from the arc in a cooling -chamber it was practical to enclose -the flame arc, thereby -increasing the life of the -carbons.</p></div></div> - -<p>The reason for the big difference in efficiency between the series -and multiple direct-current arc is that in the latter a large amount of -electrical energy (watts) is lost in the ballast resistance. While there -is a considerable difference between the inherent efficiencies of the -D. C. and A. C. arcs themselves, this difference is reduced in the<span class="pagenum" id="Page_67">67</span> -multiple D. C. and A. C. arc lamps as more watts are lost in the -resistance ballast of the multiple D. C. lamp than are lost in the -reactance ballast of the multiple A. C. lamp.</p> - -<p>This reactance gives the A. C. lamp what is called a “power-factor.” -The product of the amperes (7.5) times the volts (110) does not give -the true wattage (540) of the lamp, so that the actual volt-amperes -(825) has to be multiplied by a power factor, in this case about 65 per -cent, to obtain the actual power (watts) consumed. The reason is -that the instantaneous varying values of the alternating current and -pressure, if multiplied and averaged throughout the complete alternating -cycle, do not equal the average amperes (measured by an -ammeter) multiplied by the average voltage (measured by a volt-meter). -That is, the maximum value of the current flowing (amperes) -does not occur at the same instant that the maximum pressure -(voltage) is on the circuit.</p> - -<hr class="chap x-ebookmaker-drop" /> - -<div id="chap_39" class="chapter"> -<h2 class="nobreak" id="THE_FLAME_ARC_LAMP">THE FLAME ARC LAMP</h2> -</div> - -<p>About 1844 Bunsen investigated the effect of introducing various -chemicals in the carbon arc. Nothing was done, however, until -Bremer, a German, experimented with various salts impregnated in -the carbon electrodes. In 1898 he produced the so-called flame arc, -which consisted of carbons impregnated with calcium fluoride. This -gave a brilliant yellow light most of which came from the arc flame, -and practically none from the carbon tips. The arc operated in the -open air and produced smoke which condensed into a white powder.</p> - -<p>The two carbons were inclined downward at about a 30-degree -angle with each other, and were of small diameter but long, 18 to -30 inches, having a life of about 12 to 15 hours. The tips of the -carbons projected through an inverted earthenware cup, called the -“economizer,” the white powder condensing on this and acting not -only as an excellent reflector but making a dead air space above the -arc. The arc was maintained at the tips of the carbons by an electro-magnet -whose magnetic field “blew” the arc down.</p> - -<p>Two flame arc lamps were burned in series on 110-volt circuits. -They consumed 550 watts each, giving an efficiency of about 35 lumens -per watt on direct current. On alternating current the efficiency was -about 30 l-p-w. By use of barium salts impregnated in the carbons, -a white light was obtained, giving an efficiency of about 18 l-p-w on -direct current and about 15½ on alternating current. These figures -cover lamps equipped with clear glassware. Using strontium salts -in the carbons, a red light was obtained at a considerably lower efficiency,<span class="pagenum" id="Page_68">68</span> -such arcs on account of their color being used only to a limited -extent for advertising purposes.</p> - -<div id="i_76" class="figcenter"> - <img src="images/i_068.jpg" width="1667" height="1792" style="width: 70%;" alt="" /> - <div class="caption"><p><span class="smcap">Constant Current Transformer, 1900.</span></p> - -<p>This converted alternating current of constant voltage into constant -current, for use on series circuits.</p></div></div> - -<p>These arcs were remarkably efficient but their maintenance expense -was high. Later, about 1908, enclosed flame arcs with vertical carbons -were made which increased the life of the carbons, the smoke being -condensed in cooling chambers. However, their maintenance expense -was still high. They have now disappeared from the market, having -been displaced by the very efficient gas-filled tungsten filament incandescent -lamp which appeared in 1913.</p> - -<hr class="chap x-ebookmaker-drop" /> - -<div id="chap_40" class="chapter"> -<p><span class="pagenum" id="Page_69">69</span></p> - -<h2 class="nobreak" id="THE_CONSTANT_CURRENT_TRANSFORMER_FOR_SERIES_CIRCUITS">THE CONSTANT CURRENT TRANSFORMER FOR SERIES CIRCUITS</h2> -</div> - -<p>About 1900 the constant current transformer was developed by -Elihu Thomson. This transforms current taken from a constant -potential alternating current circuit into a constant alternating current -for series circuits, whose voltage varies with the load on the circuit. -The transformer has two separate coils; the primary being stationary -and connected to the constant potential circuit and the secondary -being movable and connected to the series circuit. The weight of the -secondary coil is slightly underbalanced by a counter weight. Current -flowing in the primary induces current in the secondary, the two -coils repelling each other. The strength of the repelling force depends -upon the amount of current flowing in the two coils. The core of the -transformer is so designed that the central part, which the two coils -surround, is magnetically more powerful close to the primary coil -than it is further away.</p> - -<p>When the two coils are close together a higher voltage is induced -in the secondary than if the later were further away from the primary -coil. In starting, the two coils are pulled apart by hand to prevent too -large a current flowing in the series circuit. The secondary coil is -allowed to gradually fall and will come to rest at a point where the -voltage induced in it produces the normal current in the series circuit, -the repelling force between the two coils holding the secondary at this -point. Should the load in the series circuit change for any reason, the -current in the series circuit would also change, thus changing the -force repelling the two coils. The secondary would therefore move -until the current in the series circuit again becomes normal. The -action is therefore automatic, and the actual current in the series -circuit can be adjusted within limits to the desired amount, by varying -the counterweight. A dash pot is used to prevent the secondary coil -from oscillating (pumping) too much.</p> - -<p>In the constant current transformer, the series circuit is insulated -from the constant potential circuit. This has many advantages. A -similar device, called an automatic regulating reactance was developed -which is slightly less expensive, but it does not have the advantage of -insulating the two circuits from each other.</p> - -<hr class="chap x-ebookmaker-drop" /> - -<div id="chap_41" class="chapter"> -<h2 class="nobreak" id="ENCLOSED_SERIES_ALTERNATING_CURRENT_ARC_LAMPS">ENCLOSED SERIES ALTERNATING CURRENT ARC LAMPS</h2> -</div> - -<p>The simplicity of the constant current transformer soon drove the -constant direct-current dynamo from the market. An enclosed arc -lamp was therefore developed for use on alternating constant current.<span class="pagenum" id="Page_70">70</span> -Two sizes of lamps were made; one for 6.6 amperes consuming 450 -watts and having an efficiency of about 4½ lumens per watt, and the -other 7.5 amperes, 480 watts and 5 l-p-w (clear glassware). These -lamps soon superseded the direct current series arcs. They have now -been superseded by the more efficient magnetite arc and tungsten -filament incandescent lamps.</p> - -<hr class="chap x-ebookmaker-drop" /> - -<div id="chap_42" class="chapter"> -<h2 class="nobreak" id="SERIES_INCANDESCENT_LAMPS_ON_CONSTANT_CURRENT_TRANSFORMERS">SERIES INCANDESCENT LAMPS ON CONSTANT CURRENT TRANSFORMERS</h2> -</div> - -<p>Series incandescent lamps were made for use on constant current -transformers superseding the “Municipal” and “Shunt Box” systems. -The large Edison, now called the Mogul Screw base, was -adopted and the short circuiting film cut-out was removed from the -base and placed between prongs attached to the socket.</p> - -<div id="i_77" class="figcenter smaller"> -<div class="figilb three"> - <img src="images/i_070a1.png" width="285" height="537" alt="" /> - <div class="caption">Holder.</div></div> - -<div class="figilb three"> - <img src="images/i_070a2.png" width="285" height="537" alt="" /> - <div class="caption">Socket.</div></div> - -<div class="figilb three"> - <img src="images/i_070a3.png" width="285" height="537" alt="" /> - <div class="caption">Holder and socket.</div></div> - -<p class="p1 center larger clear"><span class="smcap">Series Incandescent Lamp Socket with Film Cutout, 1900.</span></p> - -<p class="center">The “Large Edison,” now called Mogul Screw, base was standardized -and the short circuiting device put on the socket terminals.</p> -</div> - -<p>The transformers made for the two sizes of arc lamps, produced -6.6 and 7.5 amperes and incandescent lamps, in various sizes from -16 to 50 cp, were made for these currents so that the incandescent -lamps could be operated on the same circuit with the arc lamps. The -carbon series incandescent lamp, however, was more efficient if made -for lower currents, so 3½-, 4- and 5½-ampere constant current transformers -were made for incandescent lamps designed for these amperes. -Later, however, with the advent of the tungsten filament, the -6.6-ampere series tungsten lamp was made the standard, as it was -slightly more efficient than the lower current lamps, and was made -in sizes from 32 to 400 cp. When the more efficient gas-filled -tungsten lamps were developed, the sizes were further increased; -the standard 6.6-ampere lamps now made are from 60 to 2500 cp.</p> - -<hr class="chap x-ebookmaker-drop" /> - -<div id="chap_43" class="chapter"> -<p><span class="pagenum" id="Page_71">71</span></p> - -<h2 class="nobreak" id="THE_NERNST_LAMP">THE NERNST LAMP</h2> -</div> - -<p>Dr. Walther Nernst, of Germany, investigating the rare earths used -in the Welsbach mantle, developed an electric lamp having a burner, -or “glower” as it was called, consisting of a mixture of these oxides. -The main ingredient was zirconia, and the glower operated in the open -air. It is a non-conductor when cold, so had to be heated before current -would flow through it. This was accomplished by an electric -heating coil, made of platinum wire, located just above the glower. -As the glower became heated and current flowed through it, the heater -was automatically disconnected by an electro-magnet cut-out.</p> - -<div id="i_78" class="figcenter"> - <img src="images/i_071.png" width="993" height="1601" style="width: 42%;" alt="" /> - <div class="caption"><p><span class="smcap">Nernst Lamp, 1900.</span></p> - -<p>The burners consisted mainly of zirconium oxide which had to be -heated before current could go through them.</p></div></div> - -<p>The resistance of the glower decreases with increase in current, -so a steadying resistance was put in series with it. This consisted of<span class="pagenum" id="Page_72">72</span> -an iron wire mounted in a bulb filled with hydrogen gas and was called -a “ballast.” Iron has the property of increasing in resistance with -increase in current flowing through it, this increase being very marked -between certain temperatures at which the ballast was operated. The -lamp was put on the American market in 1900 for use on 220-volt -alternating current circuits. The glower consumed 0.4 ampere. -One, two, three, four and six glower lamps were made, consuming -88, 196, 274, 392 and 528 watts respectively. As most of the light -is thrown downward, their light output was generally given in mean -lower hemispherical candlepower. The multiple glower lamps were -more efficient than the single glower, owing to the heat radiated from -one glower to another. Their efficiencies, depending on the size, were -from about 3½ to 5 lumens per watt, and their average candlepower -throughout life was about 80 per cent of initial. The lamp disappeared -from the market about 1912.</p> - -<div id="i_79" class="figcenter"> - <img src="images/i_072.png" width="869" height="1019" style="width: 36%;" alt="" /> - <div class="caption"><span class="smcap">Diagram of Nernst Lamp.</span></div></div> - -<hr class="chap x-ebookmaker-drop" /> - -<div id="chap_44" class="chapter"> -<h2 class="nobreak" id="THE_COOPER-HEWITT_LAMP">THE COOPER-HEWITT LAMP</h2> -</div> - -<p>In 1860 Way discovered that if an electric circuit was opened -between mercury contacts a brilliant greenish colored arc was produced. -Mercury was an expensive metal and as the carbon arc seemed -to give the most desirable results, nothing further was done for many -years until Dr. Peter Cooper Hewitt, an American, began experimenting<span class="pagenum" id="Page_73">73</span> -with it. He finally produced an arc in vacuum in a one-inch glass -tube about 50 inches long for 110 volts direct current circuits, which -was commercialized in 1901. The tube hangs at about 15 degrees from -the horizontal. The lower end contains a small quantity of mercury. -The terminals are at each end of the tube, and the arc was first started -by tilting the tube by hand so that a thin stream of mercury bridged -the two terminals. Current immediately vaporized the mercury, -starting the arc. A resistance is put in series with the arc to maintain -the current constant on direct current constant voltage circuits. -Automatic starting devices were later developed, one of which consisted -of an electro-magnet that tilted the lamp, and the other of an -induction coil giving a high voltage which, in discharging, started the -arc.</p> - -<div id="i_80" class="figcenter"> - <img src="images/i_073.png" width="1500" height="652" style="width: 62%;" alt="" /> - <div class="caption"><p><span class="smcap">Cooper-Hewitt Mercury Vapor Arc Lamp, 1901.</span></p> - -<p>This gives a very efficient light, practically devoid of red but of high -actinic value, so useful in photography.</p></div></div> - -<p>This lamp is particularly useful in photography on account of the -high actinic value of its light. Its light is very diffused and is practically -devoid of red rays, so that red objects appear black in its light. -The lamp consumes 3½ amperes at 110 volts direct current (385 -watts) having an efficiency of about 12½ lumens per watt.</p> - -<p>The mercury arc is peculiar in that it acts as an electric valve -tending to let current flow through it only in one direction. Thus on -alternating current, the current impulses will readily go through it -in one direction, but the arc will go out in the other half cycle unless -means are taken to prevent this. This is accomplished by having two -terminals at one end of the tube, which are connected to choke coils, -which in turn are connected to a single coil (auto) transformer. The -alternating current supply mains are connected to wires tapping different -parts of the coil of the auto transformer. The center of the<span class="pagenum" id="Page_74">74</span> -coil of the auto transformer is connected through an induction coil -to the other end of the tube. By this means the alternating current -impulses are sent through the tube in one direction, one half cycle -from one of the pairs of terminals of the tube, the other half cycle -from the other terminal. Thus pulsating direct current, kept constant -by the induction coil, flows through the tube, the pulsations overlapping -each other by the magnetic action of the choke coils. This -alternating current lamp is started by the high voltage discharge -method. It has a 50-inch length of tube, consuming about 400 watts -on 110 volts. Its efficiency is a little less than that of the direct current -lamp.</p> - -<div id="i_81" class="figcenter"> - <img src="images/i_074.png" width="1567" height="960" style="width: 66%;" alt="" /> - <div class="caption"><p><span class="smcap">Diagram of Cooper-Hewitt Lamp for Use on Alternating Current.</span></p> - -<p>The mercury arc is inherently for use on direct current, but -by means of reactance coils, it can be operated on alternating -current.</p></div></div> - -<hr class="chap x-ebookmaker-drop" /> - -<div id="chap_45" class="chapter"> -<h2 class="nobreak" id="THE_LUMINOUS_OR_MAGNETITE_ARC_LAMP">THE LUMINOUS OR MAGNETITE ARC LAMP</h2> -</div> - -<p>About 1901 Dr. Charles P. Steinmetz, Schenectady, N. Y., studied -the effect of metallic salts in the arc flame. Dr. Willis R. Whitney, -also of Schenectady, and director of the research laboratory of the -organization of which Dr. Steinmetz is the consulting engineer, followed -with some further work along this line. The results of this -work were incorporated in a commercial lamp called the magnetite arc -lamp, through the efforts of C. A. B. Halvorson, Jr., at Lynn, Mass. -The negative electrode consists of a pulverized mixture of magnetite<span class="pagenum" id="Page_75">75</span> -(a variety of iron ore) and other substances packed tightly in an -iron tube. The positive electrode is a piece of copper sheathed in -iron to prevent oxidization of the copper. The arc flame gives a -brilliant white light, and, similar to the mercury arc, is inherently -limited to direct current. It burns in the open air at about 75 volts. -The lamp is made for 4-ampere direct current series circuits and -consumes about 310 watts and has an efficiency of about 11½ lumens -per watt.</p> - -<div id="i_82" class="figcenter"> - <img src="images/i_075.png" width="1253" height="1225" style="width: 52%;" alt="" /> - <div class="caption"><p><span class="smcap">Luminous or Magnetite Arc Lamp, 1902.</span></p> - -<p>This has a negative electrode containing magnetite which produces -a very luminous white flame in the arc stream.</p></div></div> - -<p>The negative (iron tube) electrode now has a life of about 350 -hours. Later, a higher efficiency, 4-ampere electrode was made which -has a shorter life but gives an efficiency of about 17 l-p-w, and a 6.6-ampere -lamp was also made giving an efficiency of about 18 l-p-w using -the regular electrode. This electrode in being consumed gives off -fumes, so the lamp has a chimney through its body to carry them off. -Some of the fumes condense, leaving a fine powder, iron oxide, in the -form of rust. The consumption of the positive (copper) electrode is -very slow, which is opposite to that of carbon arc lamps on direct -current. The arc flame is brightest near the negative (iron tube)<span class="pagenum" id="Page_76">76</span> -electrode and decreases in brilliancy and volume as it nears the positive -(copper) electrode.</p> - -<div id="i_83" class="figcenter"> - <img src="images/i_076.png" width="1349" height="1494" style="width: 56%;" alt="" /> - <div class="caption"><p><span class="smcap">Diagram of Series Magnetite Arc Lamp.</span></p> - -<p>The method of control, entirely different from that of other -arc lamps, was invented by Halvorson to meet the peculiarities of -this arc.</p></div></div> - -<p>The peculiarities of the arc are such that Halvorson invented an -entirely new principle of control. The electrodes are normally apart. -In starting, they are drawn together by a starting magnet with sufficient -force to dislodge the slag which forms on the negative electrode -and which becomes an insulator when cold. Current then flows -through the electrodes and through a series magnet which pulls up a -solenoid breaking the circuit through the starting magnet. This allows -the lower electrode to fall a fixed distance, about seven-eighths of an -inch, drawing the arc, whose voltage is then about 72 volts. As -the negative electrode is consumed, the length and voltage of the arc<span class="pagenum" id="Page_77">77</span> -increases when a magnet, in shunt with the arc, becomes sufficiently -energized to close the contacts in the circuit of the starting magnet -causing the electrode to pick up and start off again.</p> - -<hr class="chap x-ebookmaker-drop" /> - -<div id="chap_46" class="chapter"> -<h2 class="nobreak" id="MERCURY_ARC_RECTIFIER_FOR_MAGNETITE_ARC_LAMPS">MERCURY ARC RECTIFIER FOR MAGNETITE ARC LAMPS</h2> -</div> - -<div id="i_84" class="figcenter"> - <img src="images/i_077.png" width="966" height="1237" style="width: 40%;" alt="" /> - <div class="caption"><p><span class="smcap">Mercury Arc Rectifier Tube for Series Magnetite -Arc Lamps, 1902.</span></p> - -<p>The mercury arc converted the alternating constant current into direct -current required by the magnetite lamp.</p></div></div> - -<p>As the magnetite arc requires direct current for its operation, the -obvious way to supply a direct constant current for series circuits is -to rectify, by means of the mercury arc, the alternating current obtained -from a constant current transformer. The terminals of the -movable secondary coil of the constant current transformer are connected -to the two arms of the rectifier tube. One end of the series -circuit is connected to the center of the secondary coil. The other -end of the series circuit is connected to a reactance which in turn is -connected to the pool of mercury in the bottom of the rectifier tube. -One-half of the cycle of the alternating current goes from the -secondary coil to one arm of the rectifier tube through the mercury -vapor, the mercury arc having already been started by a separate<span class="pagenum" id="Page_78">78</span> -starting electrode. It then goes to the pool of mercury, through the -reactance and through the series circuit. The other half cycle of -alternating current goes to the other arm of the rectifier tube, through -the mercury vapor, etc., and through the series circuit. Thus a pulsating -direct current flows through the series circuit, the magnetic action -of the reactance coil making the pulsations of current overlap each -other, which prevents the mercury arc from going out.</p> - -<div id="i_85" class="figcenter"> - <img src="images/i_078.jpg" width="1346" height="1238" style="width: 56%;" alt="" /> - <div class="caption"><span class="smcap">Early Mercury Arc Rectifier Installation.</span></div></div> - -<hr class="chap x-ebookmaker-drop" /> - -<div id="chap_47" class="chapter"> -<h2 class="nobreak" id="INCANDESCENT_LAMP_DEVELOPMENTS_18941904">INCANDESCENT LAMP DEVELOPMENTS, 1894–1904</h2> -</div> - -<p>With the development of a waterproof base in 1900, by the use of -a waterproof cement instead of plaster of Paris to fasten the base to -the bulb, porcelain at first and later glass being used to insulate the -terminals of the base from each other, lamps could be exposed to the -weather and give good results. Electric sign lighting therefore received -a great stimulus, and lamps as low as 2 candlepower for 110 -volts were designed for this purpose. Carbon lamps with concentrated -filaments were also made for stereoptican and other focussing purposes. -These lamps were made in sizes from 20 to 100 candlepower. -The arc lamp was more desirable for larger units.</p> - -<p><span class="pagenum" id="Page_79">79</span></p> - -<p>The dry battery was made in small units of 2, 3 and 5 cells, so -that lamps of about ⅛ to 1 candlepower were made for 2½, 3½ and -6½ volts, for portable flashlights. It was not however until the -tungsten filament was developed in 1907 that these flashlights became -as popular as they now are. For ornamental lighting, lamps were -supplied in round and tubular bulbs, usually frosted to soften the -light.</p> - -<div id="i_86" class="figcenter"> - <img src="images/i_079.jpg" width="1630" height="1409" style="width: 68%;" alt="" /> - <div class="caption"><p><span class="smcap">The Moore Tube Light, 1904.</span></p> - -<p class="justify">This consisted of a tube about 1¾ inches in diameter and having -a length up to 200 feet, in which air at about one thousandth part of -atmospheric pressure was made to glow by a very high voltage alternating -current.</p></div></div> - -<hr class="chap x-ebookmaker-drop" /> - -<div id="chap_48" class="chapter"> -<h2 class="nobreak" id="THE_MOORE_TUBE_LIGHT">THE MOORE TUBE LIGHT</h2> -</div> - -<p>Geissler, a German, discovered sixty odd years ago, that a high -voltage alternating current would cause a vacuum tube to glow. This -light was similar to that obtained by Hawksbee over two hundred -years ago. Geissler obtained his high voltage alternating current by a -spark coil, which consisted of two coils of wire mounted on an iron -core. Current from a primary battery passed through the primary<span class="pagenum" id="Page_80">80</span> -coil, and this current was rapidly interrupted by a vibrator on the -principle of an electric bell. This induced an alternating current of -high voltage in the secondary coil as this coil had a great many more -turns than the primary coil had. Scientists found that about 70 per -cent of the electrical energy put into the Geissler tube was converted -into the actual energy in the light given out.</p> - -<p>In 1891 Mr. D. McFarlan Moore, an American, impressed with the -fact that only one-half of one per cent of the electrical energy put -into the carbon-incandescent lamp came out in the form of light, decided -to investigate the possibilities of the vacuum tube. After -several years of experiments and the making of many trial lamps, -he finally, in 1904, made a lamp that was commercially used in considerable -numbers.</p> - -<div id="i_87" class="figcenter"> - <img src="images/i_080.png" width="839" height="832" style="width: 36%;" alt="" /> - <div class="caption"><p><span class="smcap">Diagram of Feeder Valve of Moore Tube.</span></p> - -<p class="justify">As the carbon terminals inside the tube absorbed the very slight -amount of gas in the tube, a feeder valve allowed gas to flow in the -tube, regulating the pressure to within one ten thousandth part of an -atmosphere above and below the normal extremely slight pressure -required.</p></div></div> - -<p>The first installation of this form of lamp was in a hardware store -in Newark, N. J. It consisted of a glass tube 1¾ inches in diameter -and 180 feet long. Air, at a pressure of about one-thousand part of -an atmosphere, was in the tube, from which was obtained a pale pink -color. High voltage (about 16,000 volts) alternating current was -supplied by a transformer to two carbon electrodes inside the ends -of the tube. The air had to be maintained within one ten-thousandth -part of atmospheric pressure above and below the normal of one-thousandth, -and as the rarefied air in the tube combined chemically -with the carbon electrodes, means had to be devised to maintain the<span class="pagenum" id="Page_81">81</span> -air in the tube at this slight pressure as well as within the narrow -limits required.</p> - -<p>This was accomplished by a piece of carbon through which the air -could seep, but if covered with mercury would make a tight seal. As -the air pressure became low, an increased current would flow through -the tube, the normal being about a tenth of an ampere. This accordingly -increased the current flowing through the primary coil of the -transformer. In series with the primary coil was an electro-magnet -which lifted, as the current increased, a bundle of iron wires mounted -in a glass tube which floated in mercury. The glass tube, rising, -lowered the height of the mercury, uncovering a carbon rod cemented -in a tube connecting the main tube with the open air. Thus air could -seep through this carbon rod until the proper amount was fed into the -main tube. When the current came back to normal the electro-magnet -lowered the floating glass tube which raised the height of the mercury -and covered the carbon rod, thus shutting off the further supply of -air.</p> - -<p>As there was a constant loss of about 400 watts in the transformer, -and an additional loss of about 250 watts in the two electrodes, the -total consumption of the 180-foot tube was about 2250 watts. Nitrogen -gas gave a yellow light, which was more efficient and so was later -used. On account of the fixed losses in the transformer and electrodes -the longer tubes were more efficient, though they were made in various -sizes of from 40 to 200 feet. The 200-foot tube, with nitrogen, had -an efficiency of about 10 lumens per watt. Nitrogen gas was supplied to -the tube by removing the oxygen from the air used. This was accomplished -by passing the air over phosphorous which absorbed the -oxygen.</p> - -<p>Carbon dioxide gas (CO<sub>2</sub>) gave a pure white light but at about half -the efficiency of nitrogen. The gas was obtained by allowing hydrochloric -acid to come in contact with lumps of marble (calcium carbonate) -which set free carbon dioxide and water vapor. The latter was -absorbed by passing the gas through lumps of calcium chloride. The -carbon dioxide tube on account of its daylight color value, made an -excellent light under which accurate color matching could be done. -A short tube is made for this purpose and this is the only use which -the Moore tube now has, owing to the more efficient and simpler -tungsten filament incandescent lamp.</p> - -<hr class="chap x-ebookmaker-drop" /> - -<div id="chap_49" class="chapter"> -<p><span class="pagenum" id="Page_82">82</span></p> - -<h2 class="nobreak" id="THE_OSMIUM_LAMP">THE OSMIUM LAMP</h2> -</div> - -<p>Dr. Auer von Welsbach, the German scientist who had produced -the Welsbach gas mantle, invented an incandescent electric lamp -having a filament of the metal osmium. It was commercially introduced -in Europe in 1905 and a few were sold, but it was never -marketed in this country. It was generally made for 55 volts, two -lamps to burn in series on 110-volt circuits, gave about 25 candlepower -and had an initial efficiency of about 5½ lumens per watt. It -had a very fair maintenance of candlepower during its life, having -an average efficiency of about 5 l-p-w. Osmium is a very rare and -expensive metal, usually found associated with platinum, and is therefore -very difficult to obtain. Burnt out lamps were therefore bought -back in order to obtain a supply of osmium. It is also a very brittle -metal, so that the lamps were extremely fragile.</p> - -<div id="i_88" class="figcenter"> - <img src="images/i_082.png" width="359" height="835" style="width: 16%;" alt="" /> - <div class="caption"><p><span class="smcap">Osmium Lamp, 1905.</span></p> - -<p>This incandescent lamp was used in Europe for a few years, but -was impractical to manufacture in large quantities as osmium is -rarer and more expensive than platinum.</p></div></div> - -<hr class="chap x-ebookmaker-drop" /> - -<div id="chap_50" class="chapter"> -<h2 class="nobreak" id="THE_GEM_LAMP">THE GEM LAMP</h2> -</div> - -<p>Dr. Willis R. Whitney, of Schenectady, N. Y., had invented an -electrical resistance furnace. This consisted of a hollow carbon -tube, packed in sand, through which a very heavy current could be -passed. This heated the tube to a very high temperature, the sand -preventing the tube from oxidizing, so that whatever was put inside -the tube could be heated to a very high heat. Among his various<span class="pagenum" id="Page_83">83</span> -experiments, he heated some carbon filaments and found that the high -temperature changed their resistance “characteristic” from negative -to positive. The ordinary carbon filament has a resistance when hot -that is less than when it is cold, which was reversed after heating it -to the high temperature Dr. Whitney was able to obtain. These filaments -were made into lamps for 110-volt service and it was found -that they could be operated at an efficiency of 4 lumens per watt. The -lamps also blackened less than the regular carbon lamp throughout -their life.</p> - -<div id="i_89" class="figcenter"> - <img src="images/i_083.png" width="384" height="807" style="width: 16%;" alt="" /> - <div class="caption"><p><span class="smcap">Gem Lamp, 1905.</span></p> - -<p class="justify">This incandescent lamp had a graphitized carbon filament obtained -by the heat of an electric furnace, so that it could be operated at -25 per cent higher efficiency than the regular carbon lamp. This lamp -is in the exhibit of Edison lamps in the Smithsonian Institution.</p></div></div> - -<p>This lamp was put on the market in 1905 and was called the Gem -or metallized carbon filament lamp as such a carbon filament had a -resistance characteristic similar to metals. At first it had two single -hair pin filaments in series which in 1909 were changed to a single -loop filament like the carbon lamp.</p> - -<p>In 1905 the rating of incandescent lamps was changed from a -candlepower to a wattage basis. The ordinary 16-candlepower carbon -lamp consumed 50 watts and was so rated. The 50-watt Gem lamp -gave 20 candlepower, both candlepower ratings being their mean -candlepower in a horizontal direction. The Gem lamp was made for -110-volt circuits in sizes from 40 to 250 watts. The 50-watt size -was the most popular, many millions of which were made before the -lamp disappeared from use in 1918. The lamp was not quite as -strong as the carbon lamp. Some Gem lamps for series circuits were<span class="pagenum" id="Page_84">84</span> -also made, but these were soon superseded by the tungsten-filament -lamp which appeared in 1907.</p> - -<hr class="chap x-ebookmaker-drop" /> - -<div id="chap_51" class="chapter"> -<h2 class="nobreak" id="THE_TANTALUM_LAMP">THE TANTALUM LAMP</h2> -</div> - -<div id="i_90" class="figcenter"> - <img src="images/i_084.png" width="383" height="808" style="width: 16%;" alt="" /> - <div class="caption"><p><span class="smcap">Tantalum Lamp, 1906.</span></p> - -<p class="justify">The tantalum filament could be operated at 50 per cent greater efficiency -than that of the regular carbon incandescent lamp. This lamp -is in the exhibit of Edison lamps in the Smithsonian Institution.</p></div></div> - -<p>Dr. Werner von Bolton, a German physicist, made an investigation -of various materials to see if any of them were more suitable than -carbon for an incandescent-lamp filament. After experimenting with -various metals, tantalum was tried. Tantalum had been known to -science for about a hundred years. Von Bolton finally obtained some -of the pure metal and found it to be ductile so that it could be drawn -out into a wire. As it had a low specific resistance, the wire filament -had to be much longer and thinner than the carbon filament. A great -number of experimental lamps were made so that it was not until -1906 that the lamp was put on the market in this country. It had an -initial efficiency of 5 lumens per watt and a good maintenance of -candle power throughout its life, having an average efficiency of about -4¼ l-p-w. The usual sizes of lamps were 40 and 80 watts giving -about 20 and 40 candlepower respectively. It was not quite as -strong as the carbon lamp, and on alternating current the wire crystallized -more rapidly, so that it broke more easily, giving a shorter life -than on direct current. It disappeared from use in 1913.</p> - -<hr class="chap x-ebookmaker-drop" /> - -<div id="chap_52" class="chapter"> -<p><span class="pagenum" id="Page_85">85</span></p> - -<h2 class="nobreak" id="INVENTION_OF_THE_TUNGSTEN_LAMP">INVENTION OF THE TUNGSTEN LAMP</h2> -</div> - -<p>Alexander Just and Franz Hanaman in 1902 were laboratory assistants -to the Professor of Chemistry in the Technical High School in -Vienna. Just was spending his spare time in another laboratory in -Vienna, attempting to develop a boron incandescent lamp. In August -of that year he engaged Hanaman to aid him in his work. They conceived -the idea of making a lamp with a filament of tungsten and for -two years worked on both lamps. The boron lamp turned out to be -a failure. Their means were limited; Hanaman’s total income was -$44 per month and Just’s was slightly more than this. In 1903 they -took out a German patent on a tungsten filament, but the process they -described was a failure because it produced a filament containing -both carbon and tungsten. The carbon readily evaporated and quickly -blackened the bulb when they attempted to operate the filament at an -efficiency higher than that possible with the ordinary carbon filament. -Finally in the latter part of the next year (1904) they were able to -get rid of the carbon and produced a pure tungsten filament.</p> - -<p>Tungsten had been known to chemists for many years by its compounds, -its oxides and its alloys with steel, but the properties of the -pure metal were practically unknown. It is an extremely hard and -brittle metal and it was impossible at that time to draw it into a wire. -Just and Hanaman’s process of making a pure tungsten filament consisted -of taking tungsten oxide in the form of an extremely fine -powder, reducing this to pure tungsten powder by heating it while -hydrogen gas passed over it. The gas combined with the oxygen -of the oxide, forming water vapor which was carried off, leaving the -tungsten behind.</p> - -<p>The tungsten powder was mixed with an organic binding material, -and the paste was forced by very high pressure through a hole drilled -in a diamond. This diamond die was necessary because tungsten, -being so hard a substance, would quickly wear away any other kind of -die. The thread formed was cut into proper lengths, bent the shape of -a hair pin and the ends fastened to clamps. Current was passed -through the hair pin in the presence of hydrogen gas and water -vapor. The current heated the hair pin, carbonized the organic binding -material in it, the carbon then combining with the moist hydrogen -gas, leaving the tungsten particles behind. These particles were -sintered together by the heat, forming the tungsten filament. Patents -were applied for in various countries, the one in the United States on -July 6, 1905.</p> - -<p><span class="pagenum" id="Page_86">86</span></p> - -<p>The two laboratory assistants in 1905 finally succeeded in getting -their invention taken up by a Hungarian lamp manufacturer. By the -end of the year lamps were made that were a striking success for they -could be operated at an efficiency of 8 lumens per watt. They were -put on the American market in 1907, the first lamp put out being the -100-watt size for 110-volt circuits. This was done by mounting -several hair pin loops in series to get the requisite resistance, tungsten -having a low specific resistance. The issue of the American patent -was delayed owing to an interference between four different parties, -each claiming to be the inventor. After prolonged hearings, one -application having been found to be fraudulent, the patent was finally -granted to Just and Hanaman on February 27, 1912.</p> - -<div id="i_91" class="figcenter"> - <img src="images/i_086.png" width="637" height="1325" style="width: 28%;" alt="" /> - <div class="caption"><p><span class="smcap">Tungsten Lamp, 1907.</span></p> - -<p class="justify">The original 100 watt tungsten lamp was nearly three times as efficient -as the carbon lamp, but its “pressed” filament was very fragile. -This lamp is in the exhibit of Edison lamps in the Smithsonian -Institution.</p></div></div> - -<p>This “pressed” tungsten filament was quite fragile, but on account -of its relatively high efficiency compared with other incandescent -lamps, it immediately became popular. Soon after its introduction -it became possible to make finer filaments so that lamps for 60, 40<span class="pagenum" id="Page_87">87</span> -and then 25 watts for 110-volt circuits were made available. Sizes -up to 500 watts were also made which soon began to displace the -enclosed carbon arc lamp. Lamps were also made for series circuits -in sizes from 32 to 400 candlepower. These promptly displaced the -carbon and Gem series lamps. The high efficiency of the tungsten -filament was a great stimulus to flashlights which are now sold by the -millions each year. The lighting of railroad cars, Pullmans and -coaches, with tungsten lamps obtaining their current from storage -batteries, soon superseded the gas light formerly used. In some cases, -a dynamo, run by a belt from the car axle, kept these batteries -charged.</p> - -<div id="i_92" class="figcenter"> - <img src="images/i_087.png" width="389" height="815" style="width: 18%;" alt="" /> - <div class="caption"><p><span class="smcap">Drawn Tungsten Wire Lamp, 1911.</span></p> - -<p class="justify">Scientists had declared it impossible to change tungsten from a -brittle to ductile metal. This, however, was accomplished by -Dr. Coolidge, and drawn tungsten wire made the lamp very sturdy. -This lamp is in the exhibit of Edison lamps in the Smithsonian -Institution.</p></div></div> - -<hr class="chap x-ebookmaker-drop" /> - -<div id="chap_53" class="chapter"> -<h2 class="nobreak" id="DRAWN_TUNGSTEN_WIRE">DRAWN TUNGSTEN WIRE</h2> -</div> - -<p>After several years of patient experiment, Dr. William D. Coolidge -in the research laboratory of a large electrical manufacturing company -at Schenectady, N. Y., invented a process for making tungsten -ductile, a patent for which was obtained in December, 1913. Tungsten -had heretofore been known as a very brittle metal, but by means of -this process it became possible to draw it into wire. This greatly simplified -the manufacture of lamps and enormously improved their -strength. Such lamps were commercially introduced in 1911.</p> - -<p>With drawn tungsten wire it was easier to coil and therefore concentrate -the filament as required by focusing types of lamps. The<span class="pagenum" id="Page_88">88</span> -automobile headlight lamp was among the first of these, which in 1912 -started the commercial use of electric light on cars in place of oil -and acetylene gas. On street railway cars the use of tungsten lamps, -made possible on this severe service by the greater sturdiness of the -drawn wire, greatly improved their lighting. Furthermore, as the -voltage on street railway systems is subject to great changes, the -candlepower of the tungsten filament has the advantage of varying -but about half as much as that of the carbon lamp on fluctuating -voltage.</p> - -<div id="i_93" class="figcenter"> - <img src="images/i_088.jpg" width="1645" height="941" style="width: 68%;" alt="" /> - <div class="caption"><p><span class="smcap">Quartz Mercury Vapor Lamp, 1912.</span></p> - -<p class="justify">The mercury arc if enclosed in quartz glass can be operated at -much higher temperature and therefore greater efficiency. The light -is still deficient in red but gives a considerable amount of ultra-violet -rays which kill bacteria and are very dangerous to the eye. -They can, however, be absorbed by a glass globe. The lamp is not -used as an illuminant in this country, but is valuable for use in the -purification of water.</p></div></div> - -<hr class="chap x-ebookmaker-drop" /> - -<div id="chap_54" class="chapter"> -<h2 class="nobreak" id="THE_QUARTZ_MERCURY_VAPOR_ARC_LAMP">THE QUARTZ MERCURY VAPOR ARC LAMP</h2> -</div> - -<p>By putting a mercury arc in a tube made of quartz instead of glass, -it can be operated at a much higher temperature and thereby obtain -a greater efficiency. Such a lamp, however, is still largely deficient -in red rays, and it gives out a considerable amount of ultra-violet -rays. These ultra-violet rays will kill bacteria and the lamp is being -used to a certain extent for such purpose as in the purification of -water. These rays are very dangerous to the eyes, but they are absorbed -by glass, so as an illuminant, a glass globe must be used on the -lamp. These lamps appeared in Europe about 1912 but were never<span class="pagenum" id="Page_89">89</span> -used to any extent in this country as an illuminant. They have an -efficiency of about 26 lumens per watt. Quartz is very difficult to -work, so the cost of a quartz tube is very great. The ordinary bunsen -gas flame is used with glass, but quartz will only become soft in -an oxy-hydrogen or oxy-acetylene flame.</p> - -<div id="i_94" class="figcenter"> - <img src="images/i_089.png" width="859" height="1287" style="width: 36%;" alt="" /> - <div class="caption"><p><span class="smcap">Gas Filled Tungsten Lamp, 1913.</span></p> - -<p class="justify">By operating a coiled filament in an inert gas, Dr. Langmuir was -able to greatly increase its efficiency, the gain in light by the higher -temperature permissible, more than offsetting the loss of heat by convection -of the gas. This lamp is in the exhibit of Edison lamps in the -Smithsonian Institution.</p></div></div> - -<hr class="chap x-ebookmaker-drop" /> - -<div id="chap_55" class="chapter"> -<h2 class="nobreak" id="THE_GAS-FILLED_TUNGSTEN_LAMP">THE GAS-FILLED TUNGSTEN LAMP</h2> -</div> - -<p>The higher the temperature at which an incandescent lamp filament -can be operated, the more efficient it becomes. The limit in -temperature is reached when the material begins to evaporate rapidly, -which blackens the bulb. The filament becoming thinner more quickly, -thus rupturing sooner, shortens the life. If, therefore, the evaporating -temperature can by some means be slightly raised, the efficiency -will be greatly improved. This was accomplished by Dr. Irving -Langmuir in the research laboratories at Schenectady, N. Y., by -operating a tungsten filament in an inert gas. Nitrogen was first<span class="pagenum" id="Page_90">90</span> -used. The gas circulating in the bulb has the disadvantage of conducting -heat away from the filament so that the filament was coiled. This -presented a smaller surface to the currents of gas and thereby reduced -this loss. The lamps were commercially introduced in 1913 and a -patent was granted in April, 1916.</p> - -<div id="i_95" class="figcenter"> - <img src="images/i_090.png" width="411" height="834" style="width: 18%;" alt="" /> - <div class="caption"><p><span class="smcap">Gas Filled Tungsten Lamp, 1923.</span></p> - -<p>This is the form of the lamp as at present made. For 110-volt -circuits the sizes range from 50 to 1000 watts.</p></div></div> - -<p>An increased amount of electrical energy is required in these lamps -to offset the heat being conducted away by the gas. This heat loss -is minimized in a vacuum lamp, the filament tending to stay hot on the -principle of the vacuum bottle. This loss in a gas filled lamp becomes -relatively great in a filament of small diameter, as the surface in proportion -to the volume of the filament increases with decreasing diameters. -Hence there is a point where the gain in temperature is offset -by the heat loss. The first lamps made were of 750 and 1000 watts for -110-volt circuits. Later 500- and then 400-watt lamps were made. The -use of argon gas, which has a poorer heat conductivity than nitrogen, -made it possible to produce smaller lamps, 50-watt gas-filled lamps for -110-volt circuits now being the smallest available. In the present -state of the art, a vacuum lamp is more efficient than a gas-filled lamp -having a filament smaller than one consuming about half an ampere. -Thus gas-filled lamps are not now practicable much below 100 watts -for 220 volts, 50 watts for 110 volts, 25 watts for 60 volts, 15 watts -for 30 volts, etc.</p> - -<p>From the foregoing it will be seen that the efficiency of these lamps -depends largely on the diameter of the filament. There are other<span class="pagenum" id="Page_91">91</span> -considerations, which also apply to vacuum lamps, that affect the -efficiency. Some of these are: the number of anchors used, as they -conduct heat away; in very low voltage lamps having short filaments -the relative amount of heat conducted away by the leading-in wires -becomes of increasing importance, etc. The 1000-watt lamp for 110-volt -circuits is now made for nearly 20½ lumens per watt; the 50-watt -lamp a little over 10 l-p-w.</p> - -<p>The advent of the tungsten filament and especially the gas-filled -lamp sounded the doom of all other electric illuminants except the -magnetite and mercury arc lamps. All other incandescent lamps have -now practically disappeared. The flame arc as well as the enclosed -carbon arc lamp are hardly ever seen. The simplicity of the incandescent -lamp, its cleanliness, low first cost, low maintenance cost and -high efficiency of the tungsten filament have been the main reasons -for its popularity.</p> - -<hr class="chap x-ebookmaker-drop" /> - -<div id="chap_56" class="chapter"> -<h2 class="nobreak" id="TYPES_AND_SIZES_OF_TUNGSTEN_LAMPS_NOW_MADE">TYPES AND SIZES OF TUNGSTEN LAMPS NOW MADE</h2> -</div> - -<p>There are about two hundred different types and sizes of tungsten -filament lamps now standard for various kinds of lighting service. -For 110-volt service, lamps are made in sizes from 10 to 1000 watts. -Of the smaller sizes, some are made in round and tubular-shaped bulbs -for ornamental lighting. In addition there are the candelabra lamps -used in ornamental fixtures. Twenty-five- to five hundred-watt lamps -are made with bulbs of special blue glass to cut out the excess of red -and yellow rays and thus produce a light approximating daylight.</p> - -<p>For 220-volt service lamps are made in sizes of from 25 to 1000 -watts. For sign lighting service, 5-watt lamps of low voltage are -made for use on a transformer located near the sign to reduce the -110 volts alternating current to that required by the lamps. Lamps -are made from 5 to 100 watts for 30-volt service, such as is found in -train lighting and in gas engine driven dynamo sets used in rural -homes beyond the reach of central station systems. Concentrated -filament lamps are made for stereopticon and motion picture projection, -floodlighting, etc., in sizes from 100 to 1000 watts, for street -railway headlights in sizes below 100 watts and for locomotive headlights -in sizes from 100 to 250 watts. For series circuits, used in -street lighting, lamps are made from 60 to 2500 candlepower. Miniature -lamps cover those for flashlight, automobile, Christmas-tree, -surgical and dental services, etc. They range, depending on the -service, from ½ to 21 candlepower, and in voltage from 2½ to 24.</p> - -<p><span class="pagenum" id="Page_92">92</span></p> - -<div id="i_96" class="figcenter"> - <img src="images/i_092.png" width="1676" height="2803" style="width: 68%;" alt="" /> - <div class="caption"><p><span class="smcap">Standard Tungsten Lamps, 1923.</span></p> - -<p>This illustrates some of the two hundred different lamps -regularly made.</p></div></div> - -<hr class="chap x-ebookmaker-drop" /> - -<div id="chap_57" class="chapter"> -<p><span class="pagenum" id="Page_93">93</span></p> - -<h2 class="nobreak" id="STANDARD_VOLTAGES">STANDARD VOLTAGES</h2> -</div> - -<p>Mention has been made of 110-volt service, 220-volt service, etc. -In the days of the carbon incandescent lamp it was impossible to -manufacture all lamps for an exact predetermined voltage. The -popular voltage was 110, so lighting companies were requested in a -number of instances to adjust their service to some voltage other -than 110. They were thus able to utilize the odd voltage lamps -manufactured, and this produced a demand for lamps of various -voltages from 100 to 130. Arc lamps had a resistance (reactance on -alternating current) that was adjustable for voltages between 100 -and 130.</p> - -<p>Similarly a demand was created for lamps of individual voltages -of from 200 to 260. The 200- to 260-volt range has simmered down -to 220, 230, 240 and 250 volts. These lamps are not as efficient as -the 110-volt type and their demand is considerably less, as the 110-volt -class of service for lighting is, with the exception of England, -almost universal. Thus 110-volt service means 100 to 130 volts in -contra-distinction to 200 to 260 volts, etc. The drawn tungsten wire -filament made it possible to accurately predetermine the voltage of -the lamp, so now that the carbon incandescent lamp is a thing of the -past, there is no need for so many different voltages. Several years -ago standard voltages of 110, 115 and 120 were recommended for -adoption by all the electrical societies in the United States, and practically -all central stations have now changed their service to one of -these voltages.</p> - -<hr class="chap x-ebookmaker-drop" /> - -<div id="chap_58" class="chapter"> -<h2 class="nobreak" id="COST_OF_INCANDESCENT_ELECTRIC_LIGHT">COST OF INCANDESCENT ELECTRIC LIGHT</h2> -</div> - -<p>In the early ’80’s current was expensive, costing a consumer on the -average about twenty cents per kilowatt hour. The cost has gradually -come down and the general average rate for which current is sold -for lighting purposes is now about 4½ cents. During the period 1880 -to 1905 the average efficiency of carbon lamps throughout their life -increased from about one to over 2¾ lumens per watt and their list -price decreased from one dollar to twenty cents. The average amount -of light obtained for one cent at first was about five candlepower hours -and in 1904 it was increased to over thirty-six at the average rate -then in effect. The next year with the more efficient Gem lamp 44 -candle-hours could be had for one cent. In 1906 the amount was -increased to 50 with the tantalum lamp and with the tungsten lamp -in 1907, even at its high price of $1.50, the amount was further -increased to 63. Since then the average cost of current has been<span class="pagenum" id="Page_94">94</span> -reduced but slightly, but the efficiency of the tungsten lamp has -materially increased and its cost reduced so that it is now possible to -obtain, with the ordinary 40-watt lamp 170 candle-hours for a cent. -If the gas-filled tungsten lamp were used the amount of light now -obtained for a cent would depend upon the size, which, for the 1000-watt -lamp, would be 382 candle-hours.</p> - -<hr class="chap x-ebookmaker-drop" /> - -<div id="chap_59" class="chapter"> -<h2 class="nobreak" id="STATISTICS_REGARDING_THE_PRESENT_DEMAND_FOR_LAMPS">STATISTICS REGARDING THE PRESENT DEMAND FOR LAMPS</h2> -</div> - -<p>In the United States there are about 350 million incandescent and -about two hundred thousand magnetite arc lamps now (1923) in use. -They are increasing about 10 per cent each year. The annual demand -for incandescent lamps for renewals and new installations is over -200 millions, exclusive of miniature lamps. The use of incandescent -lamps in all other countries put together is about equal that in the U. S.</p> - -<p>The average candlepower of standard lighting lamps has increased -from 16, which prevailed during the period prior to 1905, to over 60. -The average wattage has not varied much during the past twenty-odd -years, the average lamp now consuming about 55 watts. This indicates -that the public is utilizing the improvement in lamp efficiency -by increased illumination. The present most popular lamp is the 40-watt -size which represents 20 per cent of the total demand. Second -in demand is the 25-watt at 18 per cent and third, the 50-watt at 15 -per cent of the total in numbers. While the aggregate demand of all -the gas-filled tungsten lamps is a little over 20 per cent in numbers, -they represent, on account of their greater efficiency and wattage, over -half the amount of total candlepower used. In the United States -about 85 per cent of all lamps are for the 110-volt range. About 5 -per cent for 220 volts, 2 per cent for street series lighting, 3 per cent -for street railway and 5 per cent for trainlighting and miscellaneous -classes of service.</p> - -<hr class="chap x-ebookmaker-drop" /> - -<div id="chap_60" class="chapter"> -<p><span class="pagenum" id="Page_95">95</span></p> - -<h2 class="nobreak" id="SELECTED_BIBLIOGRAPHY">SELECTED BIBLIOGRAPHY</h2> -</div> - -<div class="blockquot hang"> - -<p><span class="smcap">Alglave and Boulard</span>, “The Electric Light,” translated by -T. O’Connor Sloane, edited by C. M. Lungren, D. Appleton & -Co., New York, 1884.</p> - -<p><span class="smcap">Barham, G. Basil</span>, “The Development of the Incandescent Electric -Lamp,” Scott Greenwood & Son, London, 1912.</p> - -<p><span class="smcap">Dredge, James</span>, “Electric Illumination,” 2 vols., John Wiley & Sons, -New York, 1882.</p> - -<p><span class="smcap">Durgin, William A.</span>, “Electricity—Its History and Development,” -A. C. McClurg & Co., Chicago, 1912.</p> - -<p><span class="smcap">Dyer & Martin</span>, “Edison, His Life and Inventions,” 2 vols., Harper -& Bros., New York, 1910.</p> - -<p><span class="smcap">Guillemin, Amedee</span>, “Electricity and Magnetism,” edited by Silvanus -P. Thompson, McMillan & Co., London, 1891.</p> - -<p><span class="smcap">Houston, Edwin J.</span>, “Electricity One Hundred Years ago and To-day,” -The W. J. Johnston Co., New York, 1894.</p> - -<p><span class="smcap">Houston and Kennelly</span>, “Electric Arc Lighting,” McGraw Publishing -Co., New York, 1906.</p> - -<p><span class="smcap">Hutchinson, Rollin W., Jr.</span>, “High Efficiency Electrical Illuminants -and Illumination,” John Wiley & Sons, New York, 1911.</p> - -<p><span class="smcap">Maier, Julius</span>, “Arc and Glow Lamps,” Whittaker & Co., London, -1886.</p> - -<p><span class="smcap">Pope, Franklin Leonard</span>, “Evolution of the Electric Incandescent -Lamp,” Boschen & Wefer, New York, 1894.</p> - -<p><span class="smcap">Solomon, Maurice</span>, “Electric Lamps,” D. Van Nostrand Co., New -York, 1908.</p> -</div> - -<div class="chapter"><div class="transnote"> -<h2 class="nobreak" id="Transcribers_Notes">Transcriber’s Notes</h2> - -<p>Punctuation, hyphenation, and spelling were made -consistent when a predominant preference was found -in the original book; otherwise they were not changed.</p> - -<p>Simple typographical errors were corrected; unbalanced -quotation marks were remedied when the change was -obvious, and otherwise left unbalanced.</p> - -<p>Illustrations in this eBook have been positioned -between paragraphs. In versions -of this eBook that support hyperlinks, the page -references in the List of Illustrations lead to the -corresponding illustrations.</p> - -<p>“Allesandro Volta” was printed that way.</p> -</div></div> - -<div style='display:block; margin-top:4em'>*** END OF THE PROJECT GUTENBERG EBOOK HISTORY OF ELECTRIC LIGHT ***</div> -<div style='text-align:left'> - -<div style='display:block; margin:1em 0'> -Updated editions will replace the previous one—the old editions will -be renamed. -</div> - -<div style='display:block; margin:1em 0'> -Creating the works from print editions not protected by U.S. copyright -law 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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