Hassenplug Bridge, named for the family who lived in the nearby brick house, was built with all wood members secured at the joints with wooden pins and iron bolts and was patterned after Theodore Burr’s 1804 design. With the advent of iron members in bridge building, Burr trusses were simplified, and in 1840 Squire Whipple of Utica, New York, joined the arched upper chord with the straight lower chord to form the Bowstring Truss in wood and iron. At the same time, William Howe joined the straight upper and lower chords with iron and wood members to create the Howe Truss. In 1847 Squire Whipple published A Work on Bridge Building, containing the first analysis of stresses in truss members, and he is acknowledged as a pioneer of modern bridge design. To preserve the major portion of this relic, the commissioners removed the original wood floor system and had a modern steel bridge built entirely within the old wooden structure in 1959.