_First Trials._ Very little was known as to the effects of alighting on the ground with such a rigid affair as this vessel, therefore the cars were made like boats so that the airship could alight and float on the water. The first trials were made over Lake Constance in July, 1900. The mammoth craft was housed in a huge floating shed, and the vessel emerged from it with the gas bag floating above and the two cars touching the water. She rose easily from the water, and then began a series of mishaps such as usually fall to the lot of experimenters. The upper cross stay proved too weak for the long body of the balloon and bent upward about 10 inches during the flight. This prevented the propeller shafts from working properly. Then the winch which worked the sliding weight was broken and, finally, the steering ropes to the rudders became entangled. In spite of all this, a speed of 13 feet per second, or about 9 miles per hour, was obtained. These breakages made it necessary to descend to the lake for repairs and in alighting the framework was further damaged by running into a pile in the lake. The airship was repaired and another flight was made later in the year, during which a speed of 30 feet per second, or 20 miles per hour, was obtained. _Second Airship._ Zeppelin had sunk his own private fortune and that of his supporters in his first venture, and it was not till five years later that he succeeded in raising enough money to construct a second airship. No radical changes in construction were made in the new model, but there were slight improvements made in all its details. The balloon was about 8 feet shorter than the original and the propellers were enlarged. Three vertical rudders were placed in front and three behind the balloon, and below the end of the craft horizontal rudders were installed to assist in steering upward or downward. The steering was taken care of from the front car. The most important change was made possible by the improvement in gasoline engines during the preceding five years. Where, in the earlier model, he had two 16-horsepower engines, he now used an 85-horsepower engine in each car, with practically the same weight. In fact, the total weight of the vessel was only 9 tons, while his first airship weighed 10 tons. His new craft made many successful flights. One was made at the rate of 38 miles per hour and continued for seven hours, covering a total distance of 266 miles. *Later Zeppelins.* The later Zeppelins embody no remarkable changes in design, the principal alteration being in size. One of these is illustrated in Fig. 16. In this the gas bag was increased to 446 feet in length and it held over 460,000 cubic feet of gas. This gave it a total lifting power of 16 tons. With this, Zeppelin made a voyage of over 375 miles. He was in the air for twenty hours on this trip and carried eleven passengers with him. [Illustration: Fig. 16. Zeppelin Airship in Flight]