Bowstring Truss Bridges
The Change Bridge at Palmyra
The story of The Erie Canal becomes more interesting the more it's told. Enjoy each of our Classroom Collection video clips, and don't forget to scroll down this page for more images and information!
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Squire Whipple, the man who invented the Aldrich Chain Bridge in 1858, was correct. Writing about the benefits of using iron rather than wood in bridge construction, Whipple said that, "The iron bridge gives fair promise of enduring for ages". By applying his mathematical training, Whipple added science to the art of bridge building. The formulas that he developed and published carefully calculated the stress that iron could endure. The bow-string trusses that he patented and used in his bridges proved their strength as well as their beauty. Dozens, if not hundreds of these bow-string truss bridges once crossed the Erie Canal. The 74-foot by 14-foot cast and wrought iron bridge here in Aqueduct Park is Whipple's oldest known surviving structure and one of the oldest iron truss bridges in the country.