. Bulletin - United States National Museum. Science. I igure 23, I in 1 )\i \ si K\ i\ lv. man iri ss hri»c;i . .11 \;<-. Maryland. I lit- bridge was built elsewhere in 1852 and was moved to this now-abandoned Baltimore and Ohio industrial siding in about 1888. hi 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 struc- tural theory, availability of a greater variety of rolled structural shapes, and the increasing; loading patt
. Bulletin - United States National Museum. Science. I igure 23, I in 1 )\i \ si K\ i\ lv. man iri ss hri»c;i . .11 \;<-. Maryland. I lit- bridge was built elsewhere in 1852 and was moved to this now-abandoned Baltimore and Ohio industrial siding in about 1888. hi 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 struc- tural theory, availability of a greater variety of rolled structural shapes, and the increasing; loading patterns of the period all contributed. 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; .1 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 ich really ripe age. The sole known remaining example (fig. 2 i) stands on Mich a branch—ironically, at Savage, over the Little Patuxent, the site of the first Bollman -pan. 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. PAPER 36: ENGINEERING CONTRIBUTIONS OF WENDEL BOLLMAN L'Jl 527 67—7 97. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original United States National Museum; Smithsonian Institution; United States. Dept. of the Interior. Washington : Smithsonian Institution Press, [etc. ]; for sale by the Supt. of Docs. , U. S. Govt Print. Off.
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