Page:Popular Science Monthly Volume 40.djvu/415

Rh, so as to utilize their reaction. The vibrating tube resumes its original shape, and the wings rise. Promptly, the barrel, carried on by its cog-work, brings a cartridge under the hammer, which falls; a second explosion is produced, and the phenomena already described are repeated in their order. During the third, fourth, and so on to the twelfth explosion, the bird flies over a horizontal distance of seventy-five or eighty metres, sustaining itself against gravity and steadily rising. Instead of the bird falling straight down at the end of its course, the wings, kept up by the drawing together of the branches of the tube and the silken aëroplane (C, Fig. 1), the surface of which is proportioned to the weight of the imitation animal, act as a parachute, and the apparatus descends obliquely and slowly. The aëroplane, which is represented by dotted lines, connects the head of the bird with the helm, and with the wings and the tail. The use of the aëroplane will always be of advantage, whatever the power of the motor; for its surface, constantly proportionate to the total weight, will serve to prevent any accident in case of the sudden arrest of the motor machine. We repeat that, in the apparatus of large dimensions, a reservoir of compressed hydrogen is substituted for the cartridges of the small model; while the use of aluminum is suggested by its lightness and the probability of its being obtainable at a reasonable price. We also remark that the extensive cooling surface of the vibrating tube and its direct contact with the air, which will be closer as the velocity is greater, will keep it at a moderate temperature; yet there will be little danger of its getting heated, for the simplicity of the mechanism, and the removal of all transmission by rotation or sliding, will prevent the necessity of using lubricants or refrigerants. In short, the combined advantages of the generator-motor-propeller constitute it the lightest aviator that it is possible to construct. It possesses, we dare say, all the warrantees of ascensional power and return.

We shall be glad if we have succeeded in this summary in conveying to our readers the faith we have in the possibility and the near realization of practical navigation of the air; if the subject has any further interest for them, they will find a general serious and profound discussion of it in a book by M, Barral, and also full descriptions of a number of sustaining machines which we have devised, including the one we have just presented to them. Constructed during the siege of 1870, it is the first machine heavier than the air susceptible of construction on a large scale and capable of traveling by its own force. The crowning experiment in the navigation of the air now depends only on capital and secondary studies; and, again, in centering our efforts on the discovery of a strong and light motor, we believe we were the first (in 1870)