CONTRIBUTIONS FROM THE MUSEUM OF HISTORY AND TECHNOLOGY: PAPER 36 THE ENGINEERING CONTRIBUTIONS OF WENDEL BOLLMAN _Robert M. Vogel_ EARLY CAREER 80 THE BOLLMAN TRUSS 85 W. BOLLMAN AND COMPANY 91 FINAL USE OF THE BOLLMAN TRUSS 95 KNOWN BOLLMAN WORKS 99 BIBLIOGRAPHY 104 [Illustration: Figure 1.--WENDEL BOLLMAN, C.E. (1814-1884). (_Photo courtesy of Dr. Stuart Christhilf._)] _Robert M. Vogel_ THE ENGINEERING CONTRIBUTIONS OF WENDEL BOLLMAN _The development of structural engineering has always been as dependent upon the availability of materials as upon the expansion of theoretical concepts. Perhaps the greatest single step in the history of civil engineering was the introduction of iron as a primary structural material in the 19th century; it quickly released the bridge and the building from the confines of a technology based upon the limited strength of masonry and wood._ _Wendel Bollman, self-taught Baltimore civil engineer, was the first to evolve a system of bridging in iron to be consistently used on an American railroad, becoming one of the pioneers who ushered in the modern period of structural engineering._ THE AUTHOR: _Robert M. Vogel is curator of civil engineering in the Smithsonian Institution's Museum of History and Technology._ Wendel Bollman's name survives today solely in association with the Bollman truss, and even in this respect is known only to a few older civil and railroad engineers. The Bollman system of trussing, along with those of Whipple and Fink, may be said to have introduced the great age of the metal bridge, and thus, directly, the modern period of civil engineering. Bollman's bridge truss, of which the first example was built in 1850, has the very significant distinction of being the first bridging system in the world employing iron in all of its principal structural members that was used consistently on a railroad. The importance of the transition from wood to iron as a structural and bridge building material is generally recognized, but it may be well to mention certain aspects of this change.