Page:Popular Science Monthly Volume 88.djvu/100

72 ture to the foregoing, when the vacuum tube is employed as a wireless telephone. Hundreds of the bulbs are connected to a powerful battery or dynamo. The voice spoken into a telephone transmitter connected in the circuit so disturbs the electrical balance of the bulbs that powerful waves are created. The most striking example of this application was the recent feat of telephoning wirelessly from Washington to Hawaii.

Another use of the audion is in relaying the current that carries the voice over long distance telephone lines.



The other applications of the audion are of a laboratory nature. One of these applications is transforming electricity. By throwing a small lever, the outgoing current can be varied from fifty to more than a million vibrations a second.

By the combination of some of the foregoing properties of the vacuum bulb, the uncanny but delightful result, electrical music, is attained. The idea of converting the silently flowing electric current into strains of the most bewitching music is not entirely new. Many readers will recall the telharmonium, which was built at great cost several years ago and with which electrical concerts in the home were prophesied. But the telharmonium required dynamos of such variety and size that it was eventually given up because of the prohibitive cost. Music from electricity—or music from light, to be exact—goes back many years before the telharmonium. Legendary Egyptian history, three thousand years old, tells us that the rays of the descending sun, would strike weird music from the face of the statue of Memnon.

Incredible as this tale may seem to