All these great utilitarian advances have been made possible by the researches of men interested in the advancement of knowledge for its own sake. As has been pointed out recently by Dr. Hale (“The New Heavens,” Pages 87-88), “Faraday, studying the laws of electricity, discovered the principles which rendered the dynamo possible. Maxwell, Henry and Hertz, equally unconcerned with material advantage, made wireless telegraphy possible.... Wireless telephony and transcontinental telephony without wires were both rendered possible by studies of the nature of the electric discharge in vacuum tubes.” In an interview in December, 1922, Dr. Nikola Tesla gave it as his opinion, based upon experiments already carried out in his own laboratory in New York City, that power flashed through space by radio will soon be employed in all the world’s activities. “Besides bridging enormous distances in flight and wireless conversation,” he said, “modern science will span the earth with power flashed through the air by radio. Airplanes and ships and trains will carry no fuel, but will run by transmitted energy. With wireless power no one—explorers, travelers, campers—need be cut off from civilization and its comforts.” “Not only that, but we shall see at great distances by aid of wireless energy. And seeing our neighbors across the oceans will make for a united social and political world.” FOOTNOTES: [32] See his “Experimental Researches in Electricity,” _Everyman’s Library Series_. [33] Maxwell, James Clerk, “Treatise on Electricity and Magnetism,” 1873. [34] The theoretical investigation of the mode of discharge of a condenser had been given by Sir William Thomson (later Lord Kelvin) in 1853, in the _Philosophical Magazine_ for June of that year. [35] When all the atoms and molecules of a substance vibrate in one plane, e. g., as the plane of a train of waves would be if drawn on this page, the wave is said to be _polarized_. Ordinarily, light-rays are sent out from particles vibrating in different planes; they may be vertical or horizontal, or diagonal, or they may move in a curved path—circles or ellipses. Ordinary light-vibrations are mixed up together, vibrating in all planes, and special devices—“polarizers”—are required in order to separate any one particular vibration from the rest. [36] Crehore, Dr. Albert C., “The Mystery of Matter and Energy,” Page 28, New York, 1917. [37] By means of an induction coil coupled to a circuit containing capacity terminals, thus forming an “oscillatory circuit.” [38] Michelson, Dr. A. A., “Light Waves and Their Uses,” Pages 160-61. The gap was closed during the year 1924, heat-waves being measured which were of such great length as to merge into the shortest Hertzian or “wireless” waves. [39] See an interesting article on this question in _Science and Invention_, December, 1922, Page 744 (Vol. X, Whole No. 116). [40] Gernback, H., Editorial in _Science and Invention_, December, 1922.