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diff --git a/33912.txt b/33912.txt new file mode 100644 index 0000000..090599d --- /dev/null +++ b/33912.txt @@ -0,0 +1,1782 @@ +The Project Gutenberg EBook of The Engineering Contributions of Wendel +Bollman, by Robert M. Vogel + +This eBook is for the use of anyone anywhere at no cost and with +almost no restrictions whatsoever. You may copy it, give it away or +re-use it under the terms of the Project Gutenberg License included +with this eBook or online at www.gutenberg.org + + +Title: The Engineering Contributions of Wendel Bollman + +Author: Robert M. Vogel + +Release Date: October 20, 2010 [EBook #33912] + +Language: English + +Character set encoding: ASCII + +*** START OF THIS PROJECT GUTENBERG EBOOK THE ENGINEERING *** + + + + +Produced by Colin Bell, Joseph Cooper, Louise Pattison and +the Online Distributed Proofreading Team at +http://www.pgdp.net + + + + + + + + + +Transcriber's Notes: + +This is Paper 36 from the Smithsonian Institution United States National +Museum Bulletin 240, comprising Papers 34-44, which will also be +available as a complete e-book. + +The front material, introduction and relevant index entries from the +Bulletin are included in each single-paper e-book. + +Inconsistencies in punctuation have been corrected without note. +Inconsistent hyphenation is as per the original. + + + + + SMITHSONIAN INSTITUTION + + UNITED STATES NATIONAL MUSEUM + + BULLETIN 240 + + [Illustration] + + SMITHSONIAN PRESS + + + + + MUSEUM OF HISTORY AND TECHNOLOGY + + CONTRIBUTIONS + FROM THE + MUSEUM + OF HISTORY AND + TECHNOLOGY + + _Papers 34-44_ + _On Science and Technology_ + + SMITHSONIAN INSTITUTION . WASHINGTON, D.C. 1966 + + + + +_Publications of the United States National Museum_ + + +The scholarly and scientific publications of the United States National +Museum include two series, _Proceedings of the United States National +Museum_ and _United States National Museum Bulletin_. + +In these series, the Museum publishes original articles and monographs +dealing with the collections and work of its constituent museums--The +Museum of Natural History and the Museum of History and +Technology--setting forth newly acquired facts in the fields of +anthropology, biology, history, geology, and technology. Copies of each +publication are distributed to libraries, to cultural and scientific +organizations, and to specialists and others interested in the different +subjects. + +The _Proceedings_, begun in 1878, are intended for the publication, in +separate form, of shorter papers from the Museum of Natural History. +These are gathered in volumes, octavo in size, with the publication date +of each paper recorded in the table of contents of the volume. + +In the _Bulletin_ series, the first of which was issued in 1875, appear +longer, separate publications consisting of monographs (occasionally in +several parts) and volumes in which are collected works on related +subjects. _Bulletins_ are either octavo or quarto in size, depending on +the needs of the presentation. Since 1902 papers relating to the +botanical collections of the Museum of Natural History have been +published in the _Bulletin_ series under the heading _Contributions from +the United States National Herbarium_, and since 1959, in _Bulletins_ +titled "Contributions from the Museum of History and Technology," have +been gathered shorter papers relating to the collections and research of +that Museum. + +The present collection of Contributions, Papers 34-44, comprises +Bulletin 240. Each of these papers has been previously published in +separate form. The year of publication is shown on the last page of each +paper. + + FRANK A. TAYLOR + _Director, United States National Museum_ + + + + + CONTRIBUTIONS FROM + THE MUSEUM OF HISTORY AND TECHNOLOGY: + PAPER 36 + + THE ENGINEERING CONTRIBUTIONS + OF WENDEL BOLLMAN + + _Robert M. Vogel_ + + + + + EARLY CAREER 80 + + THE BOLLMAN TRUSS 85 + + W. BOLLMAN AND COMPANY 91 + + FINAL USE OF THE BOLLMAN TRUSS 95 + + KNOWN BOLLMAN WORKS 99 + + BIBLIOGRAPHY 104 + + + + +[Illustration: Figure 1.--WENDEL BOLLMAN, C.E. (1814-1884). (_Photo +courtesy of Dr. Stuart Christhilf._)] + + +_Robert M. Vogel_ + + +THE ENGINEERING CONTRIBUTIONS OF WENDEL BOLLMAN + + + _The development of structural engineering has always been as + dependent upon the availability of materials as upon the + expansion of theoretical concepts. Perhaps the greatest single + step in the history of civil engineering was the introduction + of iron as a primary structural material in the 19th century; + it quickly released the bridge and the building from the + confines of a technology based upon the limited strength of + masonry and wood._ + + _Wendel Bollman, self-taught Baltimore civil engineer, was the + first to evolve a system of bridging in iron to be consistently + used on an American railroad, becoming one of the pioneers who + ushered in the modern period of structural engineering._ + + THE AUTHOR: _Robert M. Vogel is curator of civil engineering in + the Smithsonian Institution's Museum of History and + Technology._ + + +Wendel Bollman's name survives today solely in association with the +Bollman truss, and even in this respect is known only to a few older +civil and railroad engineers. The Bollman system of trussing, along with +those of Whipple and Fink, may be said to have introduced the great age +of the metal bridge, and thus, directly, the modern period of civil +engineering. + +Bollman's bridge truss, of which the first example was built in 1850, +has the very significant distinction of being the first bridging system +in the world employing iron in all of its principal structural members +that was used consistently on a railroad. + +The importance of the transition from wood to iron as a structural and +bridge building material is generally recognized, but it may be well to +mention certain aspects of this change. + +The tradition of masonry bridge construction never attained the great +strength in this country which it held in Europe, despite a number of +notable exceptions. There were several reasons for this. From the very +beginning of colonization, capital was scarce, a condition that +prevailed until well into the 19th century and which prohibited the use +of masonry because of the extremely high costs of labor and transport. +An even more important economic consideration was the rapidity with +which it was necessary to extend the construction of railways during +their pioneer years. Unlike the early English and European railways, +which invariably traversed areas of dense population and industrial +activity, and were thus assured of a significant financial return almost +from the moment that the first rail was down, the Baltimore and Ohio +and its contemporaries were launched upon an entirely different +commercial prospect. Their principal business consisted not so much in +along-the-line transactions as in haulage between principal terminals +separated by great and largely desolate expanses. This meant that income +was severely limited until the line was virtually complete from end to +end, and it meant that commencement of return upon the initial +investment was entirely dependent upon the speed of survey, graduation, +tunneling, and bridging. + +[Illustration: Figure 2.--MODEL OF B. H. LATROBE'S TRUSS, built in 1838, +over the Patapsco River at Elysville (now Daniels), Maryland. (_Photo +courtesy of Baltimore and Ohio Railroad._)] + +The need for speed, the general attenuation of capital, and the simple +fact that all the early railroads traversed thickly forested areas +rendered wood the most logical material for bridge and other +construction, both temporary and permanent. + +The use of wood as a bridge material did not, of course, originate with +the railroads, or, for that matter, in this country. The heavily wooded +European countries--Switzerland in particular--had a strong tradition of +bridge construction in timber from the Renaissance on, and naturally a +certain amount of this technique found its way to the New World with the +colonials and immigrants. + +America's highway system was meager until about the time the railroad +age itself was beginning. However, by 1812 there were, along the eastern +seaboard, a number of fine timber bridges of truly remarkable structural +sophistication and workmanship. + +It was just previous to the advent of the railroads that the erection of +highway bridges in this country began to pass from an art to a science. +And an art it had been in the hands of the group of skilled but +unschooled master carpenters and masons who built largely from an +intuitive sense of proportion, stress, and the general "fitness of +things." It passed into an exact science under the guidance of a small +number of men trained at first in the scientific and technical schools +of Europe, and, after about 1820, in the few institutions then +established in America that offered technical instruction. + +The increasing number of trained engineers at first affected highway +bridge construction not so much in the materials used but in the way +they were assembled. In a bridge designed by a self-taught constructor, +the cheapness of wood made it entirely feasible to proportion the +members by enlarging them to the point where there could be no question +as to their structural adequacy. The trained engineer, on the other +hand, could design from the standpoint of determining the entire load +and then proportioning each element according to the increment of stress +upon it and to the unit capacity of the material. + +By the time railroads had started expanding to the West there had been +sufficient experience with the half dozen practical timber truss systems +by then evolved, that there was little difficulty in translating them +into bridges capable of supporting the initial light rail traffic. + +In spite of its inherent shortcomings, wood was so adaptable that it met +almost perfectly the needs of the railroads during the early decades of +their intense expansion, and, in fact, still finds limited use in the +Northwest. + + + + +Early Career + + +Wendel Bollman was born in Baltimore of German parents in 1814. His +father was a baker, who in the same year had aided in the city's defense +against the British. Wendel's education, until about the age of 11, was +more or less conventionally gained in public and private schools in +Baltimore. He then entered into informal apprenticeship, first to an +apothecary in Sheperdstown, Virginia (now West Virginia), and then to +one in Harpers Ferry. In 1826 or 1827 he became ill and returned to +Baltimore for cure. From that time on his education was entirely +self-acquired. + +[Illustration: Figure 3.--TRUSSED BEAM.] + +It is of interest, in light of his later career, to note that on the +Fourth of July 1828, he marched with other boys in a procession that was +part of the Baltimore and Ohio Railroad's cornerstone-laying ceremony. +Shortly afterward, he apprenticed himself to a carpenter for a brief +time, but when the work slacked off he obtained work with the B. & O. +The right-of-way had been graded for about five miles by that time, but +no rail was down. The boy was at first given manual work, but soon +advanced to rodman and rapidly rose as he gained facility with the +surveying apparatus. In the fall of 1829 he participated in laying the +first track. As his mother was anxious that he continue his education in +carpentry, he left the railroad in the spring of 1830 to again enter +apprenticeship. He finished, became a journeyman, helped build a +planter's mansion in Natchez, and returned to Baltimore in 1837 to +commence his own carpentry business. The next year, while building a +house in Harpers Ferry, he was asked to rejoin the B. & O. to rebuild +parts of its large timber bridge over the Potomac there, which had +fallen victim to various defects after about a year's use. + +[Illustration: Figure 4.--SIMPLE BEAM of 50-foot span with three +independent trussing systems. Bollman's use of this method of support +led to the development of his bridge truss. This drawing is of a +temporary span used after the timber bridge at Harpers Ferry was +destroyed during the Civil War. (In Baltimore and Ohio Collection, +Museum of History and Technology.)] + +Shortly after the Harpers Ferry bridge reconstruction, Bollman was made +foreman of bridges. It is apparent that, on the basis of his practical +ability, enhanced by the theoretical knowledge gained by intense +self-study, he eventually came to assist Chief Engineer Benjamin H. +Latrobe in bridge design. He later took this work over entirely as +Latrobe's attentions and talents were demanded in the location and +extension of the line between Cumberland and Wheeling. + +[Illustration: Figure 5.--BOLLMAN'S ORIGINAL PATENT DRAWING, 1851. (In +National Archives, Washington, D.C.)] + +The B. & O. did not reach its logical destination, Ohio (actually +Wheeling, West Virginia, on the east bank of the Ohio River) until 1853. +In the years following Bollman's return to the railroad, the design of +bridges was an occupation of the engineering staff second in importance +only to the location of the line itself. During this time Bollman +continued to rise and assume greater responsibilities, being appointed +master of road by Latrobe in 1848. In this position he was responsible +for all railroad property that did not move, principally the +right-of-way and its structures, including, of course, bridges. + +The recognition of Bollman's abilities was in the well-established +tradition of the B. & O., long known as America's first "school of +engineering," having sponsored many early experiments in motive power, +trackwork, and other fundamental elements of railroad engineering. It +furnished the means of expression for such men as Knight, Wright, +Whistler, Latrobe, and Winans. + +[Illustration: Figure 6.--PLAN OF HARPERS FERRY BRIDGE as built by +Latrobe. The second Winchester track was later removed.] + +Of these pioneer civil and mechanical engineers, some were formally +trained but most were self-taught. Bollman's career on the B. & O. is of +particular interest not only because he was perhaps the most successful +of the latter class but because he was probably also the last. He may be +said to be a true representative of the transitional period between +intuitive and exact engineering. Actually, his designing was a composite +of the two methods. While making consistent use of mathematical +analysis, he was at the same time more or less dependent upon empirical +methods. For years, B. & O. employees told stories of his sessions in +the tin shop of the railroad's main repair facility at Mount Clair in +Baltimore, where he built models of bridges from scraps of metal and +then tested them to destruction to locate weaknesses. It seems most +likely, however, that the empirical studies were used solely as checks +against the mathematical. + +[Illustration: Figure 7.--RECENT MODEL of Bollman's Winchester span. +Only two of the three lines of trussing are shown. The model is based on +Bollman's published description and drawings of the structure. (USNM +318171; Smithsonian photo 46941.)] + +In the period when Bollman began designing--about 1840--there were fewer +than ten men in the country designing bridges by scientifically correct +analytical methods, Whipple and Roebling the most notable of this group. +By 1884, the year of Bollman's death, the age of intuitive design had +been dead for a decade or longer. + +[Illustration: Figure 8.--THE BALTIMORE AND OHIO RAILROAD'S Potomac +River crossing at Harpers Ferry, about 1860. Bollman's iron "Winchester +span" of 1851 is seen at the right end of Latrobe's timber structure of +1836, which forms the body of the bridge. (_Photo courtesy of Harpers +Ferry National Historical Park._)] + +The B. & O. was in every way a truly pioneer enterprise. It was the +first practical railroad in America; the first to use an American +locomotive; the first to cross the Alleghenies. The spirit of innovation +had been encouraged by the railroad's directors from the outset. It +could hardly have been otherwise in light of the project's elemental +daring. + +The first few major bridges beyond the line's starting point on Pratt +Street, in Baltimore, were of rather elaborate masonry, but this may be +explained by the projectors' consciousness of the railroad's +significance and their desire for permanence. However, the +aforementioned economic factors shortly made obvious the necessity of +departure from this system, and wood was thereafter employed for most +long spans on the line as far as Harpers Ferry and beyond. Only the most +minor culverts and short spans, and those only in locations near +suitable quarries, were built of stone. + +In addition to the economic considerations which prompted the company to +revert to timber for the major bridges, there were several situations in +which masonry construction was unsuitable for practical reasons. If +stone arches were used in locations where the grade of the line was a +relatively short distance above the surface of the stream to be crossed, +a number of short arches would have been necessary to avoid a very flat +single arch. In arch construction, the smaller the segment of a circle +represented by the arch (that is, the flatter the arch), the greater the +stress in the arch ring and the resulting horizontal thrust on the +abutments. + +[Illustration: Figure 9.--BOLLMAN SKEW BRIDGE at Elysville (now +Daniels), Maryland, built in 1853-1854. (_Photo courtesy of Maryland +Historical Society._)] + +The piers for the numerous arches necessary to permit an optimum amount +of rise relative to the span would have presented a dangerous +restriction to stream flow in time of flood. By the use of timber +trusses such crossings could be made in one or two spans with, at the +most, one pier in the stream, thus avoiding the problem. + +The principal timber bridges as far west as Cumberland were of Latrobe's +design. These were good, solid structures of composite construction, in +which a certain amount of cast iron was used in joints and wrought iron +for certain tension members. They were, however, more empirical than +efficient and, for the most part, not only grossly overdesigned but of +decidedly difficult fabrication and construction. + +What is interesting about the Latrobian timber trusses, however, is the +effect they appear to have had upon Bollman's subsequent work in the +design of his own truss. This effect is evidenced by the marked analogy +between the primary structural elements of the two types. The Latrobe +truss at Elysville (fig. 2) was only partially a truss, inasmuch as the +greater part of the load was not carried from panel to panel, finally to +appear at the abutments as a pure vertical reaction, but was carried +from each panel (except the four at the center) directly to the bearing +points at the piers by heavy diagonal struts, after the fashion of the +famous 18th-century Swiss trusses of the Grubenmanns. It was a +legitimate structural device, and the simplest means of extending the +capacity of a spanning system. However, it was defective in that the +struts applied considerable horizontal thrust to the abutments, +requiring heavier masonry than would otherwise have been necessary. + +It is quite likely that Latrobe did not have absolute confidence in the +various pure truss systems already patented by Town, Long, and others, +and preferred for such strategic service a structure in which the panel +members acted more or less independently of one another. It will be seen +that, similarly, the individual panel loads in Bollman's truss were +carried to the ends of the frame by members acting independently of one +another. + + + + +The Bollman Truss + + +There had never been any question about the many serious inadequacies of +wood as a bridge material. Decay and fire risk, always present, were the +principal ones, involving continuous expenditure for replacement of +defective members and for fire watches. It was, in fact, understood by +the management and engineering staff of the B. & O. that their timber +bridge superstructures, though considered the finest in the country, +were more or less expedient and were eventually to be replaced. In this +regard it is not surprising that Latrobe, a man of considerable +foresight, had, at an early date, given serious thought to the possible +application of iron here. + +[Illustration: Figure 10.--POTOMAC RIVER CROSSING of the Baltimore and +Ohio at North Branch, Maryland, built in 1856. There are three Bollman +deck trusses. (_Photo courtesy of Baltimore and Ohio Railroad._)] + +[Illustration: Figure 11.--THE FINK TRUSS. (_Smithsonian photo +41436._)] + +[Illustration: WENDEL BOLLMAN'S + +Patent Iron Suspension Railroad Bridge. + +The undersigned would inform the officers of Railroads and others, that +he is prepared to furnish Drawings and Estimates for Bridges, Roofs, +etc., on the plan of Bollman's Patent. + +The performance of these bridges, some of which have been in use for six +years, has given entire satisfaction. Their simplicity of construction +renders repairs easy and cheap, and by a peculiar connection of the Main +and Panel Rods at the bottom of the Posts, all danger from the effects +of expansion, which has heretofore been the chief objection to Iron +Bridges, is entirely removed. + + J. H. TEGMEYER, + Baltimore, Md. + +Figure 12.--ADVERTISEMENT in the _Railroad Advocate_, August 1855.] + +The world's first major iron bridge, the famed cast-iron arch at +Coalbrookdale, England, had been constructed in 1779. Its erection was +followed by rather sporadic interest in this use of the material. The +first significant use of iron in this country was in a series of small +trussed highway arches erected by Squire Whipple over the Erie Canal in +the early 1840's, over 60 years later. In these, as in most of the +earlier iron structures, an arch of cast iron was the primary support. +The thrust of the arches was counteracted by open wrought-iron links +with other wrought- and cast-iron members contributing to the truss +action. + +The Whipple bridges promoted a certain amount of interest in the +material. In the B. & O.'s annual report for the fiscal year 1849 +appears the first record of Latrobe's interest in this important matter. +In the president's message is found the following, rather offhand, +statement: + + $6,183.19 have been expended toward the renewal of the Stone + Bridges on the Washington Branch, carried off by the flood of + Oct. 7th, 1847. Preparations are made and contracts entered + into, for the reconstruction of the large Bridges at Little + Patuxent and at Bladensburg which will be executed in a few + months.... It is proposed to erect a superstructure of Iron + upon stone abutments, at each place--with increased span, for + greater security against future floods. + +It is interesting to note that it was indeed Bollman trusses to which +the president of the railroad had referred. How much earlier than this +date Bollman had evolved his peculiar trussing system is not clear. The +certain influence of Latrobe's radiating strut system of trussing has +been mentioned. As likely an influence was another basic technique +commonly used to increase the capacity of a simple timber beam--that of +trussing--i.e., placing beneath the beam a rod of iron that was anchored +at the ends of the beam and held a certain distance below it at the +center by a vertical strut or post. This combination thus became a truss +in that the timber portion was no longer subject to a bending stress but +to a simple one of compression, the rod absorbing the tensile stress of +the combination. The effect was to deepen the beam, increasing the +distance between its extreme fibers and--by thus reducing the bending +moment--reducing the stress in them (see fig. 3). + +[Illustration: Figure 13.--THE FOUR BOLLMAN SPANS at Harpers Ferry that +survived the Civil War. The spans were completed in 1862-1863. (_Photo +courtesy of Baltimore and Ohio Railroad._)] + +It apparently occurred to Bollman that by extending the number of rods +in a longitudinal direction, this effect could be practically amplified +to such an extent as to be capable of spanning considerable distances. +He almost certainly did not at first contemplate an all-iron system, but +rather a composite one such as described. It is entirely likely that +such trussed beams, with multiple systems of tension rods, were used by +Bollman as bridging in temporary trestlework along the line as early as +1845 (see fig. 4). + +It is impossible to say whether Bollman himself, or Latrobe, was struck +with the logic of further elaborating upon the system and, +simultaneously, translating the timber compression member into one of +cast iron. Cast iron would naturally have been selected for a member +that resisted a compressive stress, as it was considerably cheaper than +wrought iron. But more important, at that time wrought iron was not +available in shapes of sufficient sectional area to resist the +appreciable buckling stresses induced in long compression members. The +cost of building up members to sufficient size from the very limited +selection of small shapes then rolled would have been prohibitive. + +The trussing rods, subjected to tension, were of wrought iron inasmuch +as the sectional area had only to be sufficient to resist the primary +axial stress. + +The first all-iron Bollman truss was constructed over the Little +Patuxent River at Savage Factory, near Laurel, Maryland, in 1850. In the +chief engineer's report for the year 1850, Latrobe was able to state +that the truss had been completed and was giving "much satisfaction." +He went on at some length to praise the "valuable mechanical features" +embodied therein, and expressed great confidence that iron would become +as important a material in the field of civil engineering as it was in +mechanical engineering. + +[Illustration: Figure 14.--THE HARPERS FERRY BRIDGE as completed after +the Civil War. It was used by the Baltimore and Ohio until 1894, and as +a highway bridge until 1936. (Photo 690, Baltimore and Ohio Collection, +Museum of History and Technology.)] + +The cost of this first major Bollman bridge was $23,825.00. Its span was +76 feet. Latrobe's confidence was well placed. The Savage span and +another at Bladensburg may be considered successful pilot models, for, +in spite of a certain undercurrent of mistrust of iron bridges within +the engineering profession--due mainly to a number of failures of +improperly designed spans--Latrobe felt there was sufficient +justification for the unqualified adoption of iron in all subsequent +major bridge structures on the B. & O. + +Almost immediately following completion of the Savage Bridge, Bollman +undertook the design of replacements for the large Patapsco River span +at Elysville (now Daniels), Maryland, and the so-called Winchester span +of the B. & O.'s largest and most important bridge, that over the +Potomac at Harpers Ferry. Harpers Ferry bridge, a timber structure, had +been designed by Latrobe and built in 1836-1837 by the noted bridge +constructor Lewis Wernwag. It was peculiar in having a turnout, near the +Virginia shore, whereby a subsidiary road branched off to Winchester +(see fig. 6). Only the single span on this line, situated between the +midriver switch and the shore, was slated for replacement, as the other +seven spans of the bridge had been virtually reconstructed in the decade +or so of their history and were in sound condition at the time. + +The Winchester span (fig. 8), which was the first Bollman truss to +embody sufficient refinement of detail to be considered a prototype, was +completed in 1851. Bollman was extremely proud of the work, with perfect +justification it may be said. The 124-foot span was fabricated in the +railroad's extensive Mount Clair shops. It was subdivided into eight +panels by seven struts and seven pairs of truss rods. An interesting +difference between this span and Bollman's succeeding bridges was his +use of granite rather than cast iron for the towers. The span consisted +of three parallel lines of trussing to accommodate a common road in +addition to the single-track Winchester line. + +The distinctive feature of the Bollman system was the previously +mentioned series of diagonal truss links in combination with a cast-iron +compression chord, which Bollman called the "stretcher." The spacing +between the chord and the junction of each pair of links was maintained +by a vertical post or strut, also cast. + +[Illustration: Figure 15.--NORTH STREET (now Guilford Avenue) bridge, +Baltimore. In this transitional composite structure cast iron was used +only in the relatively short sections of the upper chord. For the long +unsupported compression members of the web system, standard wrought-iron +angles and channels were built up into a large section. The decorative +cast-iron end posts were non-structural. (Photo in the L. N. Edwards +Collection, Museum of History and Technology.)] + +Much of the appeal of this design lay unquestionably in the sense of +security derived from the fact that each of the systems acted +independently to carry its load to the abutments. The lower chords, +actually nonfunctional in the primary structure, were included merely to +preserve the proper longitudinal spacing between the lower ends of the +struts. A certain lack of rigidity was inherent in the system due to +that very discontinuity which characterized its action; however, this +was compensated for by a pair of light diagonal stay rods crossing each +panel. These rods served the additional function of distributing +concentrated loads to adjacent struts much in the manner of the bridging +between floor joists in a building. + +In the Winchester span the floor system was of timber for reasons of +economy. This was a very minor weakness inasmuch as any stick could be +quickly replaced, and without disturbing the function of the structure. +Bollman received a patent for his truss in January 1852, and in the same +year published a booklet describing his system in general and the +Harpers Ferry span in particular. Here, he first calls it a "suspension +and trussed bridge," which is indeed an accurate designation for a +system which is not strictly a truss because it has no active lower +chord. (The analogy to a suspension bridge is quite clear, each pair of +primary rods being comparable to a suspension cable.) Thereafter, +Bollman's invention was generally termed a suspension truss. + + +INFLUENCE OF THE TRUSS + +Bollman's 1852 publication was widely disseminated here and abroad and +studied with respectful interest by the engineering profession. Its +drawings of the structure were copied in a number of leading technical +journals in England and Germany. Although there is no record that the +type was ever reproduced in Europe, there can be little doubt that this +successful structural use of iron by the most eminent railroad in the +United States and its endorsement by an engineer of Latrobe's status +gave great impetus to the general adoption of the material. This +influence was certainly equal to that of Stephenson's tubular iron +bridge of 1850 over the Menai Strait, or Roebling's iron-wire suspension +bridge of 1855 over Niagara gorge. The Bollman design had perhaps even +greater influence, as the B. & O. immediately launched the system with +great energy and in great numbers to replace its timber spans; on the +other hand, Roebling's structure was never duplicated in railroad +service, and Stephenson's only once. + +[Illustration: Figure 16.--_Left:_ CONJECTURAL SECTION of Bollman's +segmental wrought-iron column, about 1860, and section of the standard +Phoenix column; _right:_ Phoenix column as used in truss-bridge +compression members.] + + +EVALUATION OF THE TRUSS + +By the late 1850's iron was well established as a bridge material +throughout the world. Once the previous fears of iron had been stilled +and the attention of engineers was directed to the interpretation of +existing and new spanning methods into metal, the Bollman truss began to +suffer somewhat from the comparison. Although its components were simple +to fabricate and its analysis and design were straightforward, it was +less economical of material than the more conventional panel trusses +such as the Pratt and Whipple types. Additionally, there was the +requisite amount of secondary metal in lower chords and braces necessary +for stability and rigidity. + +A factor difficult to assess is Bollman's handling of his patent, which +was renewed in 1866. There is sufficient evidence to conclude that he +considered the patent valuable because it was based upon a sound design. +Therefore, he probably established a high license fee which, with the +truss's other shortcomings, was sufficient to discourage its use by +other railroads. As patron, the B. & O. had naturally had full rights to +its use. + +An additional defect, acknowledged even by Bollman, arose because of the +unequal length of the links in each group except the center one. This +caused an unevenness in the thermal expansion and contraction of the +framework, with the result that the bridges were difficult to keep in +adjustment. This had the practical effect of virtually limiting the +system to intermediate span lengths, up to about 150 feet. For longer +spans the B. & O. employed the truss of another of Latrobe's assistants, +German-born and technically trained Albert Fink. + +The Fink truss was evolved contemporaneously with Bollman's and was +structurally quite similar, being a suspension truss with no lower +chord. The principal difference was the symmetry of Fink's plan, which +was achieved by carrying the individual panel loads from the panel +points to increasingly longer panel units before having them appear at +the end bearings. This eliminated the weakness of unequal strains. The +design was basically a more rational one, and it came to be widely used +in spans of up to 250 feet, generally as a deck-type truss (see fig. +11). + + + + +W. Bollman and Company + + +Bollman resigned from the Baltimore and Ohio in 1858 to form, with John +H. Tegmeyer and John Clark, two of his former B. & O. assistants, a +bridge-building firm in Baltimore known as W. Bollman and Company. This +was apparently the first organization in the United States to design, +fabricate, and erect iron bridges and structures, pioneering in what 25 +years later had become an immense industry. The firm had its foundation +at least as early as 1855 when advertisements to supply designs and +estimates for Bollman bridges appeared over Tegmeyer's name in several +railroad journals (see fig. 12). + +Bollman's separation from the B. & O. was not a complete one. The +railroad continued its program of replacing timber bridges with Bollman +trusses, and contracted with W. Bollman and Company for design and a +certain amount of fabrication. There is some likelihood that eventually +fabrication was entirely discontinued at Mount Clair, and all parts +subsequently purchased from Bollman. + +The firm prospered, erecting a number of major railroad bridges in +Mexico, Cuba, and Chile. Operations ceased from 1861 to 1863 because of +difficult wartime conditions in the border city of Baltimore. Following +this, Bollman reentered business as sole proprietor of the Patapsco +Bridge and Iron Works. + +[Illustration: QUINCY BAY BRIDGE + +Figure 17.--CHICAGO, BURLINGTON AND QUINCY RAILROAD BRIDGE over Quincy +Bay (branch of the Mississippi River) at Quincy, Illinois. The pivot +draw-span was formed of two Bollman deck trusses supported at their +outer ends by hog chains. The bridge was built in 1867-1868 by the +Detroit Bridge and Iron Co., Bollman licensee. (Clarke, _Account of the +Iron Railway Bridge ... at Quincy, Illinois_.)] + +The most noteworthy of Bollman's works in this period was a series of +spans at Harpers Ferry. The B. & O.'s timber bridge had been destroyed +by Confederate forces in June 1861, and the crossing was thereafter made +upon temporary trestlework. This was a constant source of trouble, with +continuing interruptions of the connection from high water, washouts, +and military actions. The annoyance and expense of this became so great +that the company decided to risk an iron bridge at the crossing. In July +and August 1862, two sections of Bollman truss, spans no. 4 and no. 5 +were completed. As this occurred during the time when W. Bollman and +Company was inoperative, the work was produced at Mount Clair to +Bollman's design and, undoubtedly, erected under his supervision. Five +weeks later, on September 24, these and Bollman's famous Winchester span +of 1851 were blown up by the Confederates, and the line's business was +again placed at the mercy of trestling. + +The spirit of the B. & O. administration indeed seems to have been +unshakable when, in the face of such heartbreaking setbacks, it +determined to again bridge the river with iron, even at the height of +the hostilities. In November, span no. 5 was erected, and by April 1863 +nos. 3, 4, and 6 also. These were the four straight spans in midriver +between the "wide" (or "branch," or "wye") span and the span on the +Maryland shore over the Chesapeake and Ohio Canal (see fig. 13). +Although the wood floor system of these spans was burned for strategic +reasons by U.S. troops later in 1863, they survived the war. + +In 1868 the remaining trestlework was replaced with Bollman trusses. +This magnificent structure served the railroad until 1894 when the +right-of-way was realigned at Harpers Ferry. However, the half used by +the common road remained in use until carried away by the disastrous +flood in 1936. The piers may still be seen. + +During the prewar years, Bollman evolved a structural development of +most profound importance, which is usually associated with the Phoenix +Iron Works and its founder, Samuel J. Reeves. In the erection of a high +trestlework viaduct for the Havana Railroad, Bollman apparently became +concerned with the tensile weakness of cast iron when applied in long, +unsupported columns. Although a column is normally subjected to +compressive stresses, when the slenderness ratio--that is, the length +divided by the radius of gyration of the cross section--becomes great, a +secondary bending stress may be produced. If this stress becomes great +enough, the value of the tensile stress in one side of the column may +actually exceed the principal compressive stress, and a net effect of +tension result. + +[Illustration: Figure 18.--OHIO RIVER CROSSING of the Baltimore and Ohio +at Benwood, West Virginia, completed in 1870. Bollman deck trusses were +used in the approaches on both sides. (Photo 693, Baltimore and Ohio +Collection, Museum of History and Technology.)] + +[Illustration: Figure 19.--PATAPSCO RIVER crossing of the Baltimore and +Ohio between Thistle and Ilchester, Maryland. (Photo 695, Baltimore and +Ohio Collection, Museum of History and Technology.)] + +As already mentioned, the few available rolled-iron shapes were of +relatively small area and quite unsuitable for use as columns unless +combined and built up in complex fabrications. The normal practice at +the time was to use cast compression members in iron bridges and +structures, with their sectional area so proportioned to the length that +a state of tension could not exist. In the case of long members, this +naturally meant that an excessive amount of material was used. + +[Illustration: Figure 20.--TWO VIEWS OF BOLLMAN-BUILT "water-pipe truss" +that carries Lombard Street over Jones Falls in Baltimore. Built in +1877.] + +Bollman was conscious of the problem from his experience with the +stretchers and struts of his truss, and he must have been aware of the +great advantage which would be obtained by a practical method of forming +such members in wrought iron, the tensile resistance of which is +equivalent to the compressive. He eventually developed the forerunner of +what came to be known as the Phoenix form by having special segmental +wrought-iron shapes rolled by Morris, Tasker and Company of +Philadelphia, these shapes being combined into a circular section with +outstanding flanges for riveting together. The circular section is +theoretically the most efficient to bear compressive loading. A column +of any required diameter could be produced by simply increasing the +number of segments, the individual size of which never exceeded +contemporary rolling mill capacity (see fig. 16). + +The design exhibits the inspired combination of functional perfection +and simplicity that seems to characterize most great inventions. + +[Illustration: Figure 21.--THE HARPERS FERRY BRIDGE toward the end of +its career, carrying a common road over the Potomac. The westernmost +line of trussing and span no. 1 had been removed long before. View +through the Winchester span looking toward Maryland in 1933. (_Photo +courtesy of Harpers Ferry National Historical Park._)] + +It may have been because he had no facilities for rolling that Bollman +communicated his idea to Reeves, although this seems illogical. At any +rate, Reeves and his associates patented the system extensively, and the +Phoenix column was eventually employed to the virtual exclusion of +cast-iron and other types of wrought-iron columns. By the end of the +19th century it began to pass from use, as mills became capable of +producing larger sections with properties relatively favorable to column +use and more adaptable to connection with other members. + + + + +Final Use of the Bollman Truss + + +The Bollman truss found occasional use elsewhere than on the B. & O. +lines, but generally only when erected on contract by Patapsco Bridge +and Iron Works. However, the fact that Bollman could profitably erect +this bridge in the severely competitive 1870's indicates that the harsh +criticism of the system by authorities of such stature as Whipple was +not necessarily justified. Bollman's advertisements, in fact, refer to +the favorable recommendations of other such renowned engineers as +Herman Haupt and M. C. Meigs. + +[Illustration: Figure 22.--BOLLMAN DECK TRUSSES in the North River +Bridge built in 1873 at Mount Crawford, Virginia, on the Valley Railroad +of Virginia (B. & O.). Each end span is 98 ft. 6 in.; the river span is +148 ft. 9 in. (Photo 756, Baltimore and Ohio Collection, Museum of +History and Technology.)] + +An interesting application of the system was in a drawbridge, formed of +two Bollman deck spans, over an arm of the Mississippi at Quincy, +Illinois (see fig. 17). The first iron bridge in Mexico was erected by +Bollman over the Medellin River about 1864. Another work of this period, +which attracted considerable attention, was a pair of bridges that +Bollman erected over North Carolina's Cape Fear River in 1867-1868. +These bridges were notable for their foundation on cast-iron cylinders, +sunk pneumatically. This was one of the first instances of the use of +the process in America, and the depth of 80 feet below the water surface +reached by one cylinder was considered remarkable for years afterward. + +In the last active decade or so of his career, Bollman produced hundreds +of minor bridges and other structures. In 1873 he supplied the castings +for the splendid iron dome of Baltimore's City Hall and erected the +ingenious water-main truss which carries Lombard Street over Jones Falls +in that city. In this structure the top and bottom chords of the central +line of trussing are cast-iron water mains, bifurcated at the abutments, +and joined by cast- and wrought-iron web members (see fig. 20). + +In the mid 1870's Bollman saw his truss pass into obsolescence. This was +due primarily to the generally increasing distrust of cast iron for +major structural members due to its brittleness, but advances in +structural theory, availability of a greater variety of rolled +structural shapes, and the increasing loading patterns of the period all +contributed. + +[Illustration: Figure 23.--THE ONLY SURVIVING BOLLMAN TRUSS BRIDGE, at +Savage, Maryland. The bridge was built elsewhere in 1852 and was moved +to this now-abandoned Baltimore and Ohio industrial siding in about +1888.] + +Although no Bollman trusses were built by Bollman or the B. & O. after +1875, those in use were only removed as required by heavier motive +power. The Harpers Ferry span, as noted, remained in full main-line +service until 1894. Bollman trusses on feeder lines were continued in +use until much later; a number of them on the Valley Railroad of +Virginia (see fig. 22) were not removed until 1923. However, only on the +most isolated spurs was the Bollman truss permitted to reach really ripe +age. The sole known remaining example (fig. 23) stands on such a +branch--ironically, at Savage, over the Little Patuxent, the site of the +first Bollman span. This is not the 1850 bridge, but one built in 1852 +and moved to the present site 30 years later. The fate of the first span +is not known. + +[Illustration: Figure 24.--HOT-WATER AND CHOCOLATE PITCHERS of the +10-piece, silver tea service presented to Bollman by his fellow +employees when he resigned from the Baltimore and Ohio in 1858. A +railroad motif was used throughout, each piece being circled at top and +bottom by a track, complete with rail of accurate section and ties. +Spouts are in simulation of hexagonal sheet-iron chimneys, with seams +riveted, and the handles are in the form of a surveyor's telescope. On +the various pieces are engraved the designs of the more important B. & +O. bridges. Throughout is a wonderful profusion of bits and objects of +railroadiana in low relief, high relief, and fully modeled. In Board of +Directors Room, Baltimore and Ohio Railroad Company, Baltimore, Md. +(_Photo courtesy of Baltimore and Ohio Railroad._)] + + + + +Known Bollman Works + + +(All B. & O. works listed were designed by Bollman and built by the +railroad, unless otherwise indicated.) + + Dates of Location Type No. spans Remarks + service / length + of each + + 1850-? Savage, Md., Little Bollman 1/76' First Bollman truss + Patuxent River through erected; granite towers; + truss cost, $23,825. B. & O. RR. + + 1851-? Bladensburg, Md., Bollman 1/? Second Bollman truss + Anacostia River through erected; granite towers; + truss cost, $19,430. B. & O. RR. + + 1851-1862 Harpers Ferry, Va., Bollman 1/124' Winchester span; first + Potomac River through major Bollman truss; three + truss lines of truss; granite + towers; blown up by + Confederate Army on + September 24, 1862. + B. & O. RR. + + 1851-? Baltimore, Md., Trestle -- Wood trestle bents with + Carey Street wrought-iron diagonals. + First use of iron + structural members in + trestlework. Total length + 76 feet. B. & O. RR. + + 1852- Savage, Md., Little Bollman 2/+-80' Still standing. Moved to + Patuxent River through Savage in 1888; original + truss location unknown. This and + succeeding Bollman trusses + use iron towers. B. & O. + RR. + + 1852 (or Marriottsville, Bollman 1/50' One of first Bollman + 1853)-? Md., Patapsco River truss trusses with iron towers. + B. & O. RR. + + 1853-? Zanesville, Ohio, Bollman 4/124' Double track, Central Ohio + Muskingum River truss (or RR. Designed by Bollman; + 5/160') built by Douglas, Smith & + Co., Zanesville. + + 1854- Elysville (now Bollman 3/97'9" Upper bridge, skew. Cost, + 1870(?) Daniels), Md., through $24,477.59. B. & O. RR. + Patapsco River truss + + 1854-1862 Monocacy, Md., Bollman 3/119' Blown up September 8, + Monocacy River truss 1862; rebuilt in 1864. + Cost, $22,722.59. + B. & O. RR. + + 1854-? Eastern Ohio Bollman 1/40' C. O. RR. Section 76 + truss(?) adjacent to 300-ft. + tunnel. + + 1855-? Bridgeville, Ohio, Bollman 1/71' C. O. RR. + Salt Creek deck truss + + Pre-1855-? Buffalo, N.Y. -- -- Unidentified. Mentioned by + George Vose in Railroad + Advocate (June 9, 1855). + + 1856-? Elysville, Md., Bollman 3/111' Lower Bridge. B. & O. RR. + about 1-1/4 miles through + east of 1854 truss + bridge, Patapsco + River + + Pre-1856-? Marriottsville, Bollman 1/48'9" Referred to as "Tunnel + Md. truss(?) Bridge" in B. & O. RR. + annual report, 1856. + + 1856-? Near Ijamsville, "Iron 3/23'9" Possibly trussed beams; + Md., Bush Creek girders" mentioned in B. & O. RR. + annual report, 1856. + + 1856-? Near Ijamsville, "Iron 2/23'9" As above. + Md., Bush Creek girders" + + 1856- North Branch, Md., Bollman 3/142' Partially destroyed in + c.1862 Potomac River deck truss Civil War. B. & O. RR. + + 1860-1906 Chile, Angostura Bollman 4/115' Chilean Railways. + River truss(?) Designed and built by + Bollman. Replaced by + bridge built by French + firm of Schneider, + Cruesot & Co. + + 1860-1910 Chile, Paine River Bollman 1/? As above. + truss(?) + + Post- Ilchester, Md., Bollman 1/? B. & O. RR. + 1860-? Patapsco River through + truss + + Pre-1861-? Cuba Bridges -- All bridges on Havana + and RR., including iron + station station house and bridge + house at Guines. Designed and + built by Bollman. + + Pre-1861-? Cuba Bridges -- All bridges on Cienfuegos + RR., Cardenas RR., and + Havana & Matanzas RR. + Designed and built by + Bollman. + + Pre-1861-? Cuba Trestle -- Trestle with wrought-iron + columns (the first such + ever constructed). Havana + RR. Designed and built by + Bollman. + + 1862-1862 Harpers Ferry, Va., Bollman 2/160' Span no. 3 (July 24) and + Potomac River through span no. 4 (August 21). + truss Blown up September 24, + 1862. B. & O. RR. + + 1862-1936 Harpers Ferry, Va., Bollman 1/160' Span no. 5 (November). + Potomac River through B. & O. RR. + truss + + 1863-1936 Harpers Ferry, Va., Bollman 3/160' Spans nos. 3, 4, and 5. + Potomac River through Constructed previous to + truss April 1863. B. & O. RR. + + 1863-? Berwyn, Md., Paint Bollman ? Iron bridge mentioned in + Branch truss(?) B. & O. RR. annual report, + 1863. + + 1863(4?)-? Clinton, Iowa, Pivot 1/360' Built by Detroit Bridge + Mississippi River draw & Iron Works. It was the + longest in the world at + time of completion. + Designed by Bollman. + + 1864-? Laurel, Md., Bollman ? Replaced stone arch that + Patuxent River truss had been washed out. B. & + O. RR. + + c. 1864-? Near Veracruz, Bollman 1/115' Veracruz & Jucaro RR. + Mexico, Medellin through First iron bridge in + River truss Mexico. Designed and + built by Bollman. + + 1864-? Near Point of Bollman 1/80'(?) Iron bridge mentioned in + Rocks, Md., Back truss(?) B. & O. RR. annual + Creek report, 1864. The span + length given is that of + previous stone arch. + + 1864-? Bladensburg, Md., Bollman 1/? Span for second track, to + Anacostia River truss match 1851 span. B. & O. + RR. + + 1868-? Cape Fear, N.C., Bollman 2/146'6" Wilmington Railway Bridge + Northeast Branch, truss(?) 1/164' Co. This bridge was + Cape Fear River pivot connected to that over + draw/150' the Northwest Branch by + 2-1/2 miles of timber + trestling. Designed and + built by Bollman. + + 1868-? Cape Fear, N.C., Bollman 1/217'(?) See above. + Northwest Branch, truss(?) pivot + Cape Fear River draw/150' + + 1868-? Quincy, Ill., Bollman 4/85' Chicago, Burlington & + Quincy Bay (in deck pivot Quincy RR. The pivot draw + Mississippi River) truss draw/190' was formed of two 85-ft. + simple Bollman deck spans + whose outer ends hung from + hog chains. Designed by + Bollman; built by Detroit + Bridge & Iron Works. + + 1869- Baltimore, Md., Warren 2/100' North Avenue Bridge. + c.1892 over Jones Falls, truss 2/55'6" Composite double + B. & O. RR., and intersection truss; + Northern Central timber top chord and + RR. posts, wrought-iron lower + chord and ties. In 55-ft. + spans, both chords + timber. Cost, $73,588. + Built by Bollman. + + c.1869- Harpers Ferry, Va., Bollman 4/? Canal span (no. 8), Wide + 1936 Potomac River through span (no. 2), Winchester + truss span, and West End span. + Destroyed by flood in + 1936. B. & O. RR. + + 1870- Baltimore, Md., Iron 1/108' Charles Street Bridge. + c.1895 Jones Falls "Isometrical Three lines of trussing. + truss" Cost, $20,297. Built by + (probably Bollman. + Pratt type) + + 1870- Bellaire, Ohio- Bollman 9/107'- In approaches; 2 spans on + 1893 & Benwood W. Va., deck 125' Ohio side; 7 on West + 1900 Ohio River truss Virginia side. B. & O. RR. + + 1870- Belpre, Ohio- Bollman 16/? In approaches; 7 spans on + c.1895 Parkersburg, W. deck Ohio side; 9 on West + Va., Ohio River truss Virginia side. B. & O. RR. + + 1870-? Elysville, Md., Bollman 4/? Skew; replacement of + Patapsco River through Upper Bridge(?). B. & O. + truss RR. + + 1871- Baltimore, Md., Timber ? Decker Street (now + c.1895 Jones Falls and iron Maryland Avenue) Bridge. + truss Cost, $24,975. Built by + Bollman. + + 1871- Baltimore, Md., Warren 1/100' North Avenue Bridge. + c.1892 over Northern truss Composite double + Central RR. at intersection truss; + Jones Falls cast-iron top chord and + posts; wrought-iron + bottom chord and ties. + West span. Built by + Bollman. + + 1873-1923 Cave Station, Va., Bollman 1/98'7" Valley Railroad of + Middle River deck 1/63'5" Virginia (B. & O.) Bridge + truss no. 120. The main span + was a Whipple deck truss. + Replaced with plate + girders. Designed by + Bollman. + + 1873-1923 Mount Crawford, Bollman 2/98'6" Valley Railroad of + Va., North River deck 1/148'9" Virginia (B. & O.) Bridge + truss no. 117. Designed by + Bollman. + + 1873-1923 Verona, Va., North Bollman 3/98'7" Valley Railroad of + River deck Virginia (B. & O.) Bridge + truss no. 129. The main span + was a 147-ft. Whipple + deck truss. Designed by + Bollman. + + 1873-? Wadesville, Va., Bollman 1/147'8" Span length given is that + Opequon Creek through of previous wood span + truss that burned in 1862. B. + & O. RR. + + c. 1873- Baltimore, Md. Iron roof ? First Presbyterian + trusses Church. Built by Bollman; + possibly designed by him. + + 1873- Baltimore, Md. Cast-iron City Hall. Cost, $12,840. + stairs Designed by George A. + Frederick, architect; + built by Bollman. + + 1873- Baltimore, Md. Cast-iron Dome of the City Hall. + framework Cost, $70,525. Designed + by George A. Frederick; + built by Bollman. + + 1875- Baltimore, Md., Iron truss 1/? Fayette Street Bridge. + c.1913 Jones Falls Cost, $9,396. Built by + Bollman. + + 1876- Baltimore, Md., "Single- 1/? Canton Avenue (now Fleet + c.1913 Jones Falls beam iron Street) Bridge. Cost, + bridge" $8,904. Built by Bollman. + (truss?) + + 1876- Baltimore, Md., "Single- 1/? Eastern Avenue Bridge. + c.1913 Jones Falls beam iron Cost, $12,382. Built by + bridge" Bollman. + (truss?) + + 1877- Baltimore, Md., Pratt and 1/88'6" Lombard Street Bridge. + Jones Falls bowstring Three lines of truss; + truss two outer trusses, + composite cast- and + wrought-iron polygonal + Pratt type; center + composite bowstring with + Pratt-system web. Both + chords are cast-iron + water mains, bifurcated + at the end bearings; + cast-iron posts and + wrought-iron ties. In + service. Cost, $7,632. + Designed by Jas. Curran, + Baltimore water + department; built by + Bollman. + + 1877- Baltimore, Md., Iron truss 1/? Bath Street Bridge. Cost, + c.1913 Jones Falls $4,172. Built by Bollman. + + 1879-? Baltimore, Md. Drawbridge 1/? Over entrance to City + Dock. Cost, $13,182. + Built by Bollman. + + 1879- Baltimore, Md., Warren 2/173'9" North Street (now + c.1930 over Jones Falls truss Guilford Avenue) Bridge. + and railroad Composite trusses; + tracks cast-iron top chord and + end posts; wrought-iron + bottom chord and web + members. Cost, $38,772.45. + Built by Bollman; + designed by Latrobe. + + 1881-1960 Baltimore, Md., Wrought- 1/? Union Avenue Bridge. + (Woodberry), iron Pratt Built by Bollman; + Jones Falls truss possibly designed by him. + + ?-? Harpers Ferry, Va., Bollman 1/148' Arsenal Branch, B. & O. + Arsenal Canal through RR. Skew type. Span + truss length is that of + previous timber span. + + ?-? Baltimore, Md., Bollman 2/? B. & O. RR. + Gwynns Falls through + truss + + + + +BIBLIOGRAPHY + + +_A history and description of the Baltimore and Ohio Railroad by a +citizen of Baltimore._ Baltimore, 1853. + +Baltimore and Ohio Railroad Company. _A list of the officers and +employees of the Baltimore and Ohio Railroad for November, 1857._ +Baltimore, 1857. + +----. _Third annual report of the president and directors to the +stockholders of the Baltimore and Ohio Rail Road Company._ Baltimore: +1829. (Also the fourth through 38th annual reports. Baltimore, +1830-1864.) + +----. _Baltimore and Ohio exhibits at the Century of Progress._ Chicago, +1934. + +_Biographical cyclopedia of representative men of Maryland and the +District of Columbia._ Baltimore, 1879. + +BOLLMAN, WENDEL. _Iron suspension and trussed bridge as constructed for +the Baltimore and Ohio Rail Road Co. at Harper's Ferry, and on the +Washington branch of this road._ Baltimore, 1852. + +----. Letter to John W. Garrett dated June 17, 1862. In files of +Division of Mechanical and Civil Engineering, United States National +Museum, Washington, D.C. + +----. _Report of Mr. Bollman in relation to Central Ohio Rail Road._ +Baltimore, 1854. + +BRYANT, WILLIAM C. _Picturesque America._ New York, 1874. + +CLARKE, THOMAS CURTIS. _An account of the iron railway bridge across the +Mississippi River at Quincy, Illinois._ New York, 1869. + +COLBURN, ZERAH. American iron bridges. _Minutes of the proceedings of +the Institution of Mechanical Engineers_ (1863), vol. 22, pp. 540-573. + +CONDIT, CARL. _American building art:--The nineteenth century._ New +York: Oxford Press, 1960. + +GRAY, GEORGE E. Notes on early practice in bridge building. +_Transactions of the American Society of Civil Engineers_ (1897), vol. +37, pp. 2-16. + +GREINER, JOHN E. The American railroad viaduct--Its origin and +evolution. _Transactions of the American Society of Civil Engineers_ +(1891), vol. 25, pp. 349-372. + +LANG, PHILIP GEORGE. Bollman trusses on Valley of Virginia Branch will +soon be memories. _Baltimore and Ohio Magazine_ (October 1923), pp. +18-19. + +----. The old Baltimore and Ohio bridge crossing the Potomac River at +Harpers Ferry, West [sic] Virginia. _Engineering News-Record_ (September +17, 1931), p. 446. + +MALEZIEUX, EMILE. _Travaux publics des Etats-Unis d'Amerique en 1870._ +Paris, 1873. + +MCDOWELL, W. H. Unpublished engineer's report to the president and +directors of Wilmington Railway Bridge Company, Wilmington, North +Carolina, dated March 12, 1868. Typewritten copy in files of Division of +Mechanical and Civil Engineering, U.S. National Museum, Washington, D.C. + +SMITH, CHARLES SHALER. _Comparative analysis of the Fink, Murphy, +Bollman and triangular trusses._ Baltimore, 1865. + +SMITH, WILLIAM P. _The book of the great railway celebrations of 1857._ +Baltimore, 1858. + +TYRRELL, HENRY G. _History of bridge engineering._ Chicago, 1911. + +WHIPPLE, SQUIRE. _Bridge building._ Albany, New York, 1869. + + +U.S. GOVERNMENT PRINTING OFFICE: 1964 + +For sale by the Superintendent of Documents, U.S. Government Printing +Office Washington D.C. 20402 - Price 70 cents + + + + +INDEX + + +Bollman, W., and Company, 91, 92 + +Bollman, Wendel, 79, 80, 85, 88, 94 + + +Clark, John, 91 + + +Fink, Albert, 79, 91 + + +Grubenmann, Hans, 85 + +Grubenmann, Johann Ulrich, 85 + + +Haupt, Herman, 96 + + +Knight, ----, 83 + + +Latrobe, Benjamin H., 82, 83, 85, 87 + +Long, Stephen H., 85 + + +Meigs, M. C., 96 + +Morris, Tasker and Company, 94 + +Mount Clair shops, 83, 89, 92 + + +Patapsco Bridge and Iron Works, 92, 95 + +Phoenix Iron Works, 92 + +Pratt, Thomas W., 91 + + +Reeves, Samuel J., 92, 95 + +Roebling, John A., 83, 90 + + +Savage Factory, 88 + +Stephenson, Robert, 90 + + +Tegmeyer, John H., 91 + +Town, Ithiel, 85 + + +Wernwag, Lewis, 89 + +Whipple, Squire, 79, 83, 87, 91, 95 + +Whistler, George W., 83 + +Winans, Ross, 83 + +Wright, Benjamin, 83 + + + + + +End of the Project Gutenberg EBook of The Engineering Contributions of +Wendel Bollman, by Robert M. 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