An electric motor was installed, weighing 220 pounds, which developed 9 horse-power. The battery composed of chlorochromic salts, delivered one shaft horse-power for each 88 pounds, and this great weight seriously handicapped the performance of the airship. The first trials were made in 1884, and apparently within the limits of its propulsive power the airship was an unqualified success, so far as navigation was concerned. On one occasion it flew around Paris at an average speed of 14½ miles an hour. As early as 1872 Herr Hanlein, in Germany, built an airship of quite reasonable proportions, propelled by a 6 horse-power Lenoir gas-engine. Apparently the engine was run on gas from the envelope. A speed of 10 miles an hour or so was achieved. In 1879 Baumgartner and Wolfert built an airship with a Daimler benzine motor. An ascent was made at Leipzig in 1880, but owing to improper load distribution the vessel got out of control and was smashed on the ground. The first rigid dirigible with aluminum framework was built by an Austrian named Schwartz in 1897. This was the prototype of the Zeppelin, and no practical rigid lighter-than-air ship could now be lifted by hydrogen unless it had an aluminum framework. The invention of the gasoline engine was another tremendous advantage to the Zeppelin. M. Santos Dumont built an extraordinary collection of small airships during a period of several years commencing in 1898. His first effort was a cylinder of varnished Japanese silk, 82½ feet long and 11 feet in diameter, with pointed ends, which gave it a capacity of about 6,300 cubic feet. It was fitted with the usual internal air balloonet and a 3½ horse-power motor-cycle engine weighing 66 pounds. The engine was fitted to an ordinary balloon basket, which hung beneath the envelope and drove a two-blade propeller. The pilot also sat in the basket. The poise of the vessel was controlled by shifting weights, and steering was effected with a silk rudder stretched over a steel frame. In September, 1898, this miniature airship left the Zoological Gardens at Paris in the face of a gentle wind, and performed all sorts of evolutions in the neighborhood. M. Dumont’s No. 5 was fitted with a four-cylinder, air-cooled motor driving an enormous propeller of 26 feet in diameter, which gave a thrust of 120 pounds at 140 revolutions per minute. There is, however, some difference between this number of revolutions and the 1,400 per minute now generated by all the standard aeronautical motors. Among other novelties water ballast was used and piano wires replaced the old type suspension cords. No account of the lighter-than-air machine would be complete without mentioning the man after whom the Zeppelins were named. As a matter of fact Count Zeppelin added nothing strikingly new to his airships—he simply made them much larger than any of their predecessors; thus increasing the net lifting power and multiplying the number of engines and the horse-power.