RECENT PROGRESS IN AERIAL NAVIGATION. 303 



The task was one which involved a heavy expenditure of money, aside 

 from the time, labor, and thought bestowed by the inventor. He 

 sought in vain to organize a company with a capital of two hundred 

 thousand francs for the purpose of constructing an aerostat of three 

 thousand cubic metres capacity ; but the plan was not sufficiently 

 promising of large dividends to be attractive to investors. No for- 

 tunes have been made thus far by the navigation of the air, and capi- 

 talists have not generally manifested a self-sacrificing spirit in behalf 

 of pure science. The persevering aeronaut could find no one but his 

 brother, M. Albert Tissandier, who was confident enough to join him 

 in laying out capital for the promotion of what was generally regarded 

 as a visionary scheme. The two brothers henceforward worked to- 

 gether, the one continuing to devote himself to the perfection of the 

 electrical appliances on which reliance was to be placed, while the 

 other, who is by profession an architect, gave his attention to the me- 

 chanical construction of the aerostat. M. Gaston Tissandier had found 

 by experiments with his small aerostat that better results were to be 

 had from a battery of cells, arranged in series, where a strong acid 

 solution of potassium bichromate was the exciting liquid, than from a 

 storage-battery the energy evolved during the first few hours being 

 greater in proportion to the weight of the battery. He originated sev- 

 eral ingenious contrivances by which great lightness was secured, and 

 the liquid could be conveniently brought into contact with the zinc 

 and carbon plates, or removed at will without disturbing the plates. 



A Siemens electric motor was constructed, weighing but fifty-five 

 kilogrammes. When excited by the current from a battery of twenty- 

 four elements weighing one hundred and sixty-eight kilogrammes, this 

 motor was found capable of doing work equivalent to that of twelve 

 or fifteen men, that is, from seventy-five to one hundred kilogramme- 

 metres per second, continued through three hours, the weight of bat- 

 tery and motor together being but little in excess of the weight of 

 three men. Tissandier devised also important impi'ovements in the 

 method of generating pure hydrogen rapidly on a large scale. The 

 ascensive force of this gas when pure is about seventy-five pounds per 

 thousand cubic feet, or eleven hundred and eighty grammes per cubic 

 metre ; while that of coal-gas which has been most generally employed 

 for ballooning purposes is not more than five eighths as much. By 

 the substitution of hydrogen, the size, and consequently the expense, 

 of the balloon is correspondingly diminished. 



The aerostat constructed by M. Albert Tissandier is shown in Fig. 

 3. It is ninety-two feet long, thirty feet in its greatest diameter, with 

 capacity of about thirty-eight thousand cubic feet, and ascensive power 

 of twenty-eight hundred pounds. The propeller, nine feet in diam- 

 eter, is in the rear of the cage. Above it, and farther back, is 

 a triangular sail, to be manipulated as a rudder. On October 8, 

 1883, the first ascent was made. The air at the ground was calm, but 



