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Page:Wireless Telegraphy and Telephony (1908, Massey and Underhill).djvu/14

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Wireless Telegraphy

energy, radiated from the sun, to our earth and the other planets, as well as other influences due to myriads of heavenly bodies outside of our own solar system.

Transmission of energy through the ether takes place in the form of wave motion, and these waves are known as electromagnetic waves. Since light is one form of wave motion, we may make use of it in illustrating the presence of ether, by describing the following well-known experiment.

An ordinary electric bell and small battery are placed in what is known as a receiver, the cover being a glass dome, and an air-pump is then started which will eventually pump out all the air from the receiver in which the electric bell is ringing. Although the cover, or glass dome, is over the bell, it can be plainly heard, and the clapper can be seen vibrating rapidly. As the air is pumped out, however, the sound of the bell becomes fainter and fainter, until, finally, it is no longer heard, although the bell can still be seen as plainly as before, and the clapper vibrating as rapidly as ever. Therefore it is very evident that something remains in the receiver after the air has been removed; for, while we cannot hear the bell, we can see it, and we could not see it if there were not some medium to convey the reflected light waves from the bell to the eye.

While the earth’s atmosphere extends but a comparatively small distance, the extent of the ether is infinite.

The universe is a sea of absolute darkness, and if it