“Outside of the radio-waves that are floating about there may be hundreds of others which we have not as yet been able to register.... There may be many other waves coming to us from the sun, of which we have no knowledge today.... The human ear cannot hear below eight vibrations per second and not higher than about 30,000 vibrations per second. Certain animals can hear below and above that scale. By means of our vacuum tubes certain researches indicate that a tremendous amount of noise goes on below the eight vibrations per second, and still more noise above the 30,000 vibrations. Entirely new worlds lie in these two directions, of which nothing is known today. The vacuum tube is likely to solve these mysteries and take us into the uncharted worlds, far into the unknown, within the next few years.”[40] In March, 1922, the late Dr. Charles P. Steinmetz said that he considered well founded the supposition that performances of low-power radio sending apparatus in transmitting messages to surprising distances gave an indication that the radiations peculiar to wireless transmission pass with equal ease through the earth or through the “ether.” Such radiations would be in accordance with accepted electrical laws, as the ground, to which both the sending antennae and the receiving set are connected, would act as a return circuit for the current. Similarly, water might serve as a medium for radio conversations between ships, or between ships and the land. Moreover, it was announced during the same month that wireless telephony had been revolutionized by the successful performances of the duplex transmitters which the General Electric Company had just completed. Conversations were held between New York and passengers aboard the steamer “America,” which, at the time, was at a distance of 360 miles from shore. The three-electrode audion or vacuum tube was perfected in 1912, making radio-telephony possible. In 1921, Reginald A. Heising, a young physicist working for a degree of Master of Science at the University of Wisconsin, conceived the brilliant idea of putting into the vacuum tube the amount of energy produced by the voice, and then getting it out many times amplified in the form of high-frequency power in the antenna. This problem he soon solved, so far as the principle of the modulation system was concerned, and in 1922 the practical problem was worked out and the method all but perfected.