By Blaine Whipple, © 1998
Squire and Anna lived in Utica, N.Y., where, as a well-known civil engineer, inventor, and theoretician, he developed the first scientifically based rules for bridge construction. After graduating from Union College in Schenectady, N.Y., in 1830, he did survey work for several railroads and canal projects and made surveying instruments. In 1840 he invented a lock to weight canal boats.
The invention of the steam engine required bridges which could support heavy live loads and this motivated Squire to turn his attention to bridges. At the start of the 18th century, iron as a structural material was unknown, but as the century evolved, cast iron came into general use and wrought iron was in commercial use by century end. He invented two new truss designs and in 1853 completed a 146-foot span iron railroad bridge near West Troy (now Watervliet), N.Y.
Wooden trusses had been built according to "rule-of-thumb" methods without scientific or mathematical means to obtain accurate quantitative information on stresses. Rule-of-thumb wouldn't work with iron. It had to be analyzed scientifically and in 1847, Squire published a collection of essays entitled A Work on Bridge Building(1), the first significant theoretical formula to calculate stresses in the articulated truss. So significant is his contribution that it is the beginning of the ear of scientific bridge design. He published a more thorough and exhaustive textbook in 1869: An Elementary and Practical Treatise on Bridgebuilding(2). As a result, after 1850, most bridges were made of wrought iron until near the end of the century when replaced by steel.
Squire Whipple's Bridge at Union
College, Schnectady, N.Y.
(Courtesy of Union College's web site)
Squire developed a bowspring overhead truss with a curved upper chord made of cast-iron and the lower and intermediate members of wrought iron. His truss bridges were built throughout the United States for spans of less than 200 feet and lasted for decades. His bridge at Union College in Schenectady is a National Historic Civil Engineering Landmark.
His formula to calculate the stress in iron was also important to American architecture. If a single building type can be identified with American architecture, it is the skyscraper. Tall buildings were the stuff of stories told by legions of European immigrants whose first glimpse of America was the southern tip of Manhattan Island, bristling with its towers.
Thanks to the pursuit of metal technology--especially by bridge builders--the impulse to go ever higher could be indulged almost without limit, at least in theory. Metal beams could span great distances and could support increased loads with a minimum of bulk. Metal members could free the building's skin from its support role, permitting much larger windows as well as much greater and more flexible interior spaces to meet the growing demand in the late 19th century for offices and factories.
[Squire's Whipple lineage appears in the Whipple Database.]
1 Squire Whipple, A Work on Bridge Building: Consisting of Two Essays, the One Elementary and General, the Other Giving Original Plans and Practical Details for Iron and Wooden Bridges (Utica, N.Y.: H. H. Curtiss, 1847).
2 Squire Whipple, An Elementary and Practical Treatise on Bridgebuilding (New York: Van Nostrand, 1872).