Page:Popular Science Monthly Volume 64.djvu/391

Rh, and later by Schwarz, whose aluminum balloon proved unmanageable and was smashed in landing. The most ambitious attempt, however, was that of Count Zeppelin, who built in 1900 a monster air-ship 420 feet long and 39 feet in diameter. It was a cylinder with paraboloid ends, but the shape was inferior and almost all the lifting power was frittered away on a internal frame of aluminum, so that the gasoline motor could be of only 32 horse power, and the speed attained has variously been stated at 8 to 18 miles per hour. Nevertheless the design of Count Zeppelin contained many excellent features, and a movement is now on foot in Germany to enable him to try again, through means of a popular subscription. The mere size, if he builds again as large, is a great element of success, for as the cubic contents and lift increase as the cube of the dimensions, while the weights increase in a far smaller ratio, a balloon of this great size ought to be able to lift a very powerful motor, and to attain a speed of 30 or more miles per hour. He has shown that the size is not beyond the possibility of control.

Meanwhile gasoline motors had been increasing in efficiency and diminishing in weight. The French war department gave no sign and it was reserved for a Brazilian, Mr. Santos Dumont, to show to the Parisians what could be accomplished by equipping an air-ship with a gasoline motor. The history of his triumphs is so present to all minds that it need only be alluded to, but it may be interesting to give some details of the sizes and arrangements of his various balloons. His first idea seems to have been that, in order to make it manageable, a balloon should be made as small as possible, and that it was practicable to disencumber it of many adjuncts hitherto considered indispensable. Neglecting to study carefully what had been found out by his predecessors, he had to learn by experience, and he built five balloons, all navigables, before he produced in 1901 his No 6, with which he won the Deutsch Prize, by sailing 3 1/2 miles and return in half an hour. This balloon was 108 feet long, 20 feet in diameter and was provided with a gasoline motor of 16 horse power which might be driven up to 18 or 20 horse power. While the speed over the ground was 14 miles an hour, retarded as it was by a light wind, the speed through the air was about 19 miles an hour, a small but marked advance over any previous performance; but the result would have been still better if the shape had been that of Colonel Renard's balloon.

Since then Mr. Santos Dumont has built four new navigable balloons. His No. 7, with which he expects to compete at St. Louis in 1904, is 160 feet long and 23 feet in diameter and is to be provided with a motor of 60 horse power. His No. 8, which was sold to parties in New York last year. His No. 9, which is his visiting balloon, being only 50 feet long and 18 feet in diameter and provided with a 3 horse power motor. Its speed is only 10 miles an hour, but it is handy to