Figure 8. — The Baltimore and Ohio Railroad's Potomac River crossing at 

 Harpers Ferry, about i860. 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 age of intuitive design had been dead for a decade 

 or longer. 



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 Allcghenies. The spirit of in- 

 novation 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. 

 I he first few major bridges beyond the line's 

 starling 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. How- 

 ever, 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 quar- 

 ries, 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, 



84 



BULLETIN 240: CONTRIBUTIONS FROM THE MUSEUM OF HISTORY AND TECHNOLOGY 



