The fourth _Parseval_, a smaller vessel, was built for the Deutscher Aëro Club early in 1909. Her hull cubed 113,000 feet, and her framing was made of the strongest materials, carefully hollowed, to eliminate undue weight. At the rear of the car, on either side, were two 100-horse engines, driving two _Parseval_ propellers at a common speed, whether both engines were in operation, or only one. In many respects she resembled her immediate predecessors, and her little successor _Parseval V_ of 1,200 cubic meters capacity and 30 meters length, built for the Imperial Automobile Club.
The maneuvers at Cologne constituted the first grand demonstration of the new fleet of military dirigibles, and proved a severe test of the powers of the air ships, even when manned by experienced crews and commanded by regular military officers. Two companies of the balloon corps battalion were in attendance. Large provisions of hydrogen loaded on wagons, each carrying 100,000 cubic feet, were kept in readiness to be attached to an express train and rushed at the first alarm to any balloon in need of replenishing. On Sunday, October 31, three of the dirigibles representing each type, _Zeppelin IV_, _Parseval I_, _Gross II_, left Cologne together, by official order, and returned after flights of 7, 10 and 11 hours respectively, covering in the aggregate 930 miles. Again, leaving Cologne shortly before noon on November 3d, they went down the Rhine, simulated a concerted attack on the great fortress of Eherenbreitstein, and returned in the evening, each having covered 155 miles. And so on for many days they continued to execute maneuvers under military orders and in severe forced marches.
Count Ferdinand von Zeppelin, the famous cavalry general of Würtemburg, and hero of the Franco-Prussian war, after retiring from the army, organized, in 1898, a limited liability company for the purpose of developing a new type of dirigible which he had long contemplated. It was to be a vessel far larger and swifter than any the world had yet seen. In the summer of 1900, after two years of industrious experimental research and active construction, he brought forth from his floating laboratory on Lake Constance, near Manzell, the first of those wonderful air ships which have aroused such expectation and enthusiasm in Germany. In outward appearance and in its chief features of design it typified the whole series of motor balloons thus far developed and navigated by that illustrious inventor. Many valuable improvements were added, as a result of trial and the advance of the collateral sciences; but the fundamental plans seem to have proved as practical as they were bold and original. One by one were surmounted the greatest obstacles, physical, financial and finally political; for the Prussian Ministry did not favor his project at first, and many aëronautical adepts were adverse to it. Those huge ships faced the fury of many a tempest; their dauntless builder endured the storm of hostile criticism; but in the end, builder and ships alike won the plaudits of a proud empire and of an astonished world.