178 AERIAL NAVIGATION. 



Times edition of the Enc3^cloptedia Britannica, in the article on 

 aeronautics. Tlie most successful experiment Avas that of Professor 

 Lang-ley, who ol)tained in 1896 three flights of about three-fourths of 

 a mile each with steam-driven models, the apparatus alighting safely 

 each time and being in condition to be flown again. 



The one great fact which appears from all these various model 

 experiments is that it requires a relatively enormous power to obtain 

 support on the air. Omitting the cases in which the power was prob- 

 ably overestimated, the weights sustained were but 30 to 55 pounds to 

 the horsepower expended, thus comparing most unfavorabl}' with the 

 weights transported by land or b}^ water; for a locomotive can haul 

 about -1,000 pounds to the horsepower upon a level track, and a 

 steamer can propel a displacement of -1,000 pounds per horsepower on 

 the water at a speed of 11 miles an hour. 



But models are, to a certain extent, misleading. They seldom fly 

 twice alike and the}^ do not unfold the vicissitudes of their flight. 

 Moreover, the design for a small model is sometimes quite unsuited 

 for a large machine, just as the design for a bridge of 10 feet opening 

 is unsuited for a span of one hundred feet. 



After experimenting with models three celebrated inventors have 

 passed on to full-sized machines to carry a man. They are Maxim, 

 Ader, and Langley, and all three have been unsuccessful, simply 

 because their apparatus did not possess the required stability. They 

 might have flown had the required equilibrium and strength been duly 

 provided. 



At a cost of about $100,000, Sir Hiram Maxim built and tested in 

 1891 an enormous flying machine, to carry three men. It consisted 

 in a combination of superposed aeroplanes, portions of which bagged 

 under air pressure, and it was driven b}^ two screws 17 feet 10 inches 

 in diameter, actuated by a steam engine of 363 horsepower with steam 

 at 275 pounds pressure. The supporting surface was about 1:,000 

 square feet, and the weight 8,000 pounds. The machine ran on a 

 track of 8-feet gauge, and was prevented from unduly rising by a 

 track above it of 30-feet gauge. At a speed of 36 miles per hour all 

 the weight was sustained by the air, and on the last test the lifting 

 effect became so great that the rear axle trees were doubled up, and 

 finally one of the front wheels tore up about 100 feet of the upper 

 track, when steam was shut oft' and the machine dropped to the ground 

 and was broken. Its short flight disclosed that its stability was im- 

 perfect and Sir Hiram Maxim has not 3'et undertaken the construction 

 of the improved machine which he is understood to have had under 

 contemplation. 



Having already built, in 1872 and 1891, two full-sized flying machines 

 with doubtful results, Mr. Ader, a French electrical inventor, ])uilt, in 

 1897, a third machine at a cost of about $100,000 furnished by the 



