Figure 2. — Model of B. H. Latrobe's truss, built in 1838, over ihe Patapsco 

 River at Elysville (now Daniels), Maryland. {Photo courtesy of Baltimore and 

 Ohio Railroad.) 



Baltimore and Ohio and its contemporaries were 

 launched upon an entirely different commercial pros- 

 pect. 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. 



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 construc- 

 tion, 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. How- 

 ever, 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 



80 



BULLETIN 240: CONTRIBUTIONS FROM THE MUSEUM OF HISTORY AND TECHNOLOGY 



