Page:Popular Science Monthly Volume 28.djvu/564

548 of seven ironclad gunboats. These were designed by Mr. Eads, and be undertook to build them in sixty-five days—a short enough time under the best of circumstances; but business was then disorganized and all industrial enterprises in a chaotic condition. The materials with which the work was to be done had to be manufactured. Yet these seven heavily-plated vessels of about six hundred tons each were all finished according to contract, and another one still larger, a snag-boat, was by alterations and heavy plating made ready with the others for their armament. "Thus one individual put into construction and pushed to completion within a hundred days a powerful squadron of eight steamers aggregating five thousand tons, capable of steaming at nine knots per hour, large, heavily armed, fully equipped, and all ready for their armament of one hundred and seven large guns. The fact that such a work was done is nobler praise than any that can be bestowed by words."

In 1862 Mr. Eads was commissioned to build six more armored iron gunboats, four of which were much larger than any of the eight preceding ones. These were likewise after his own designs, four of them having two turrets each and the smaller ones one turret each. These turrets were a modification of the Ericsson turrets, the Government insisting upon these being placed upon them. He was, however, permitted to place one turret on each of two of these large gunboats, after his own design, and costing about thirty-five thousand dollars each, but on the written condition that they should be replaced by Ericsson turrets if they were not found satisfactory. The guns in these two turrets were worked by steam, and this was the first time in the history of artillery-practice when heavy guns were manipulated wholly by steam. These vessels all proved to be of lighter draught than had been stipulated, so that it was possible to add from half to three quarters of an inch to their armor; and three of them exceeded very considerably the contract speed. While these fourteen ironclads were under way, Mr. Eads also had the construction of four heavy mortar-boats and seven tin-clad or musket-proof boats. The kind of ironclads that Mr. Eads designed and constructed and the kind of work they did are recorded in the history of Grant and Halleck's campaigns, and of Farragut's capture of Mobile.

In the construction of a steel-arch bridge at St. Louis, on which he was engaged from 1867 to 1874, Mr. Eads had to deal with problems which had not before confronted an engineer. The central arch of this structure has a clear span of five hundred and twenty feet, and is pronounced, by the "British Encyclopædia," the finest specimen of metal-arch construction in the world. The side arches are five hundred and two feet each in span. All of the piers, in consequence of the shifting deposits beneath the river-bed, were sunk clear through to the bed-rock. This required them to be sunk much deeper than