Word: vacuums
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Dates: during 1920-1929
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...seen. ¶ The formation of crystals under polarized light, showing how the world would look if we had the power of seeing by ultraviolet rays. ¶ Faraday's classic magnet apparatus side by side with the latest developments of radio. The visitor can control the exhaustion of a vacuum tube, and the beautiful effects of electrical discharge through the rarefield gas. ¶ The famous dinosaur eggs discovered by the third Asiatic expedition of the American Museum of Natural History...
Nowadays the chemists have found other materials to take the place of white phosphorus, so that the "strike- anywhere" match has become a fairly digestible article. White phosphorus still finds use, however, to improve the vacuum in electric lamps, in making rat poisons, and, in smoke screens, for when a shell filled with it bursts, the phosphorus catches fire instantly and sprays its flaming drops in every direction, sending up a cloud of dense white smoke...
...control by tolls any radio inventions requiring the use of long-distance wires as connecting links, such as the multi-plex telephone and telegraph carrier systems. Also in 1917, before the radio fad had developed, it purchased from Lee DeForest, leading radio inventor, the patent rights of his audion vacuum tube, which is basic to all amplifying systems...
...most complete natural monopoly until recent inventions made it possible to broadcast long distance without the use of wires for relaying. The Company then brought suit against the independent companies in order to "stabilize the industry," in other words to protect its patent rights on vacuum tubes, modulators, amplifiers. It hopes to prevent broadcasting from stations not equipped or licensed by the A. T. & T. There are some 400 of the latter, as against 50 controlled by it. Evidence is accumulating, however, that the real fight will be between the A. T. & T. and it? three great rivals...
...Long-distance relaying is usually done by "stepping up" the wavelength of the transmitting stations from a wavelength of a few hundred metres to several thousand metres, by vacuum tube amplifiers. These waves travel much more rapidly and, without losing their power, activate the antennae of the relay stations, which again transform them into a shorter wavelength" for amateur reception...