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.
CHAPTER VI
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.
Outwardly a Zeppelin balloon may be described as a long cylinder with ogival ends and a V-shaped keel running the length of its bottom. From afar the cylinder and pointed ends appear circular in cross section, but they are sixteen-sided. About one-third the distance from either end of the great ship a small boat is suspended from the hull so closely that at those places the keel is omitted to make room. These two boats are rigidly connected with the hull and support it when the vessel rests on, or is towed along the water. Within them are the crew and petroleum engines, while above them and outward on each side of the hull, and fastened to it by outriggers, are two pairs of screw propellers, so placed as to exert their united thrust along the line of resistance. In some cases the crew can walk through the V-shaped keel from one boat to another, the passageway being illuminated here and there, by transparent covering, or windows of celluloid, along the sides and floor. Again an observer may climb up through the hull and take observations of the sky from above. Telephones, electric bells, and speaking tubes serve to transmit intelligence from one part of the vessel to another.
The frame of the hull is formed of sixteen longitudinal beams, or girders, of trellised metal work running from prow to stern and riveted at regular intervals to cross bridges of similar trellised metal work, each cross bridge being a sixteen-sided wheel with trellised rims strengthened by radial rods running inward to a central flange of sheet aluminum. Thus the body of the vessel is divided into many compartments, each bounded by two wheels, and the surrounding longitudinal beams. Each compartment contains a hydrogen balloon, or sac, which fairly fills it and exerts a lift against the longitudinal beams and against a netting formed of ramie cords stretched from wheel to wheel, diagonally between beams at their inner corners. Similarly the outward corners of the beams are joined by strong diagonal wires for the purpose of rigidity, and the whole external frame is covered with a heavy fabric which forms the outer skin, or wall of the hull. Between this skin and the hydrogen bags are air spaces, as also between bag and bag. Thus the whole vessel is buoyed up by numerous thin hydrogen sacs, protected by the frame and outer skin from the direct sun, from foul weather, and from external shocks. The gas bags are also separated from each other by the bridge work and flanges of aluminum.
PLATE X.
