ROEBLING, JollN AUGUSTUS (1806-1869), civil en-gineer, was born at Milhlhausen, Prussia, 6th June 1806. Soon after his graduation from the polytechnic school at Berlin he removed to the United States, and in 1831 entered on the practice of his profession in western Penn-sylVania. He established at Pittsburgh a manufactory of wire rope, and in May 1845 completed his first important structure, the suspended aqueduct of the Pennsylvania Canal across the Monongahela river. This was followed by the Monongahela suspension bridge at Pittsburgh and several suspended aqueducts on the Delaware and Hudson Canal. Removing his wire manufactory to Trenton, New Jersey, he began, in 1851, the erection at Niagara Falls of a long span wire suspension bridge with double roadway, for railway and carriage use (see BRIDGE, V01. iv. pp. 338-339), which was completed in 1855. Owing to the novelty of its design, the most eminent engineers, including Stevenson, regarded this bridge as foredoomed to failure; but, with its complete success, demonstrated by long use, the number of suspension bridges rapidly multiplied, the use of wire-ropes instead of chain-cables becoming all but universal. The completion, in 1867, of the still more remarkable suspension bridge over the Ohio river at Cincinnati, with a clear span of 1057 feet (see CINCINNATI, Y01. V. p. 782), added to Boebling's reputation, and his de-sign for the great bridge spanning the East River between New York and Brooklyn was accepted.' While personally engaged in laying out the towers for the bridge, Roebling received an accidental injury, which resulted in his death, at Brooklyn, from tetanus, 22d. July 1869.

At the time of his death Roebling's work on Long and Short Span Bridges (New York, 1869) was in the press. It is devoted to an exposition of his belief that " the principle of suspension will of necessity become the main feature in our future long span railway bridges," and was intended as the initial volume of a series relating to his general theory of bridge construction, with detailed plans and descriptions of the larger works erected by him.