October, 1907, witnessed the launching of _Zeppelin III_. She had the same length as her immediate predecessor, but she was a luckier vessel and better powered. On her official trial she voyaged at the height of half a mile, carrying eleven persons sixty-seven miles in two hours and seventeen minutes, or at more than twenty-nine miles per hour. This was a record velocity exceeding that of the best military balloon in France. At times she attained a velocity of fifty feet per second, thus considerably outspeeding the swiftest ocean liner. Moreover, her stability and steering qualities were excellent. With pardonable elation, therefore, the illustrious inventor could report to the Minister of War the complete success of his experiments. And with good reason the German government now granted financial aid to test more fully the merits of the rigid system of construction. With this assistance the industrious aëronaut erected a new floating house on the Borden-See at Friedrichshafen, and began the construction of a still larger air ship embodying further improvements in various details. _Zeppelin IV_ was 446 feet long, 42.5 in diameter, held 460,000 cubic feet of hydrogen in her sixteen compartments, and had a total buoyancy of sixteen tons. She had a surplus buoyancy of over two tons, carried a crew of 18 men, and had an estimated range of action of eighteen hundred miles. When drawn from her shed in the autumn of 1907, her great buoyant hull resting lightly on the water supported by her two floating cars, she had all the appearance of a royal passenger express ready for important service. In general features the vessel was like her three predecessors, but in the center of the keel, with transparent floors and windowed sides, was a special stateroom designed for passengers only. This seemed very suggestive, if not prophetic, of the future trend of aërial navigation. Moreover, the mechanism of propulsion and control were increased in power and effectiveness. In each boat-like car was a 110-horse-power Daimler benzine engine, actuating a pair of three-blade propellers about 15 feet in diameter. A large vertical rudder, mounted on the extreme end of the stern, and supplemented by a pair of smaller vertical rudders at either side of the stern, served to steer the vessel right and left. For steering up and down, as also for exerting a direct lift up or down, four superposed planes like a Venetian blind were placed at either side of the hull fore and aft, at about the same level as the propellers. In addition the hull was provided, like a feathered arrow, with fixed fin-like planes at the stern, both vertical and horizontal, for securing steadiness of flight.