Keir B. Sterling, "Haupt, Herman," American National Biography Online, February 2000, http://www.anb.org/articles/13/13-00718.html.
In 1840 Haupt helped construct the York and Wrightsville Railroad in Pennsylvania. In so doing he discovered that no American railway engineer had previously assessed the strength of railway trusses in bridge construction. He therefore completed some technical experiments, and he was later recognized as having devised a means of "representing strains of geometrical solids; deflections by parabolic areas; and the variable pressures at various parts of beams by the corresponding ordinates of plane curves" (Lord, p. 24). He continued with this work and in 1841 published an anonymous booklet, Hints on Bridge Construction. Ten years later a revised and expanded version, The General Theory of Bridge Construction, appeared under his authorship. This pioneering study became a respected text in the field.