|Truss Bridge patented by Squire Whipple|
On September 16, 1804, US-American civil engineer Squire Whipple was born. He who provided the first scientifically based rules for bridge construction and has become known as the father of iron bridge building in America.
The civil engineer was born in Hardwick, Massachusetts in 1804 the son of a farmer. He was exposed to construction sites and materials from early age, since his father designed, built and ran a cotton-spinning mill in nearby Greenwich, Massachusetts. After receiving the best common school education available he attended Hartwick Academy and Fairfield Academy located in central New York near his home. In 1830 Whipple graduated from Union College in Schenectady, New York after one year of study. He spent the decade of the 1830s serving his apprenticeship working on the Baltimore and Ohio Railroad, the Erie Canal Enlargement, the New York and Erie Railroad and several other railroads. When work was slow, he designed, built and sold mathematical instruments such as transits and engineer’s levels and drafting equipment. 
In the early 1840s, Whipple designed and built a weigh lock scale with a capacity of 300 tons to weigh the canal boats on the enlarged Erie Canal in Utica. This was probably the largest weighing device in the country at the time. After a while, Whipple became interested in the design and construction of iron and wooden bridges. Having worked on the enlargement of the Erie Canal, he knew that wooden bridges that crossed the original canal had a short-life. He also knew that the new, wider canal would require longer span bridges and must be made of a modern material, iron.[1,3]
His very first bowstring iron truss was patented in 1841. His patent showed an understanding of structural behavior of the diagonals and verticals and the need to size them to handle their loads as either tension or compression members. The engineer received his first chance to build a bridge across the canal at First Street in Utica fell. He tried to convince the Canal Commissioners that a bridge built of iron was a good long-term investment, but they were reluctant to trust a new material for their bridge. To illustrate the stability and strength of his bridge, Whipple had one built at his own expense on a vacant lot in Utica near the offices of the Canal commissioners. When the First Street Bridge fell, they approved the construction of his bridge.[1,2]
At yovisto, you may be interested in a video of the Golden Gate Bridge Opening in 1937.
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