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Figure 10. — Potomac River crossing of the Baltimore and Ohio at North 

 Branch, Maryland, built in 1856. There are three Bollman deck trusses. 

 (Photo miii tt !j of Baltimore and Ohio Railroad!) 



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86 



Figure m. The Fink truss. (Smithsonian photo 41436.) 

 HIM 1.IIX 240: ( O.NTRIBUTIONS from the museum of history and technology 



