Background
Louis Wernwag was born in Riedlingen, Württemberg, Germany.
Louis Wernwag was born in Riedlingen, Württemberg, Germany.
It is believed that he came to America in 1786 to evade military service, taking up his residence in Philadelphia. He was connected with various ventures, including the building of machines to make whetstones, the construction of powermills, experimentation in the use of anthracite coal for fuel, and the invention and improvement of nail-making machinery at the Phoenix Nail Works, Phoenixville, Pa. , in which he purchased an interest in 1813; but it is as the designer and builder of wooden bridges that his name will be chiefly remembered. His first bridge was erected in 1810 across Neshaminy Creek, on the road between Philadelphia and New York. The following year he built a drawbridge across Frankford Creek at Bridgeburg, and named it "Economy. " It was of the cantilever type, so designed that the center panel could be tipped up in order to permit masted vessels to pass through. The spans were short, but Wernwag claimed that spans of from 120 to 150 feet could be constructed on the same principle. In the later controversy as to the priority of the use of the cantilever system in the United States, his claims and his work seem to have been totally ignored. His third bridge was built in 1812 across the Schuylkill River at Upper Ferry, later the Fairmount section of Philadelphia. This structure, known as the "Colossus of Fairmount, " consisted of a single arch, the span of which was 340 feet, exceeding by nearly 100 feet the greatest existing span in America. This bold design, scientific and architecturally beautiful, probably was never surpassed in America. One Swiss bridge had a span that was fifty feet longer but was comparatively a monstrosity. The Fairmount bridge was completely destroyed by fire on September 1, 1838. In 1813 Wernwag built a bridge across the Delaware River near New Hope. , Pa. , thirty-two feet in width, divided into two wagon ways and two footways, and consisting of six arch spans of 175 feet. It had trusses with parallel chords, and vertical timber posts and iron rods for diagonals, anticipating in some respects what was later known as the Pratt type. The canal of the Schuylkill Navigation Company, one of the first in the United States, was partially constructed by him in 1817, and the Fairmount water works and dam at Philadelphia were erected in accordance with his plans. Wernwag removed to Conowingo, Md. , in 1819, where he built a bridge over the Susquehanna, and also a sawmill in which he prepared his timber. Moving to Harpers Ferry, Va. (now W. Va. ), in 1824, he purchased the Isle of Virginius, and there continued the preparation of his timber. It was his practice to saw all his timbers through the heart to detect unsound wood, and to permit good seasoning. He used no timbers of greater thickness than six inches and separated all the sticks of arches by cast washers, to allow free circulation of the air. If greater strength was needed, he increased the number but not the dimensions of the sticks. He died at Harpers Ferry.