. Bulletin - United States National Museum. Science. 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
. Bulletin - United States National Museum. Science. 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 ; It
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