Page:Popular Science Monthly Volume 40.djvu/413

 are the organs that embarrass us, can we not find some substitute?

The electrical helicopters, with which we have obtained excellent results, seem to offer a special adaptation of the screw to the motor, which, like all electric motors, turns with an excessive velocity—so that one of the organs seems made for the other. We have often been struck, in our electric boats, with the fact that the wake at the stern is hardly perceptible. This is because the helix of our steering motor-propeller, having the great velocity of twenty-four hundred turns in a minute, enters the water as a screw its tap. In our electric helicopter, likewise, the screw forms, we might say, an integral part of the motor, thus supplying us with a motor-propeller, India rubber offers a still more perfect connection between the accumulator of potential and the motor—the generator or accumulator and the motor being absolutely identical. India rubber is a generator-motor. Hence, since we can not eliminate the generator or the propeller from the apparatus we imagine, we will absorb them and fuse them into the motor. We will create a new organism sufficing for itself, and will call it the generator-motor-propeller. We have ourself devised a propeller of this kind, by the aid of the well-known Bourdon tube, an instrument which is the essential part of the Bourdon manometers. Electricity plays in it a part only secondary, but necessary. This apparatus has so far given us satisfaction, and it may be that it will serve for some time as the essential basis of machines heavier than the air.

If the pressure of the gas contained in the tube increases, the tube changes shape, and its elliptical branches tend to spread apart; while, if the pressure is diminished, inverse action takes place, and the branches approach. If, then, we provoke a series of alternate condensations and expansions, or increasing and diminishing pressures, in the interior of the tube, it will go through a series of oscillations, of strong vibrations, capable of being used as a motor force, chiefly and perhaps only in the conditions under which we have placed ourselves. For the purpose of further increasing the energy of the resistance of the tube, and also of diminishing the volume of the chamber in which the explosions are produced, we have inclosed in the interior a similar second tube—an addition which augments the elastic force of the engendered gases, while diminishing the expenditure of combustibles. The whole of the system is represented by Fig, 1, and was presented by us to the Academy of Sciences in December, 1870,

The wings A and B are fixed directly, but with a rotary motion, at the vibrating ends of the tube, suppressing all intermediary organs of transmission by friction or rotation. Depression of the wings corresponds to condensed pressures, and elevation to dilated