Radio broadcast .. (1922-30)

358 Radio Broadcast MAJOR-GENERAL JAMES G. HARBORD Who succeeded Edward J. Nally as President of the Radio Corporation of America, on January ist. He is a former Rough Rider, a veteran of the war in Cuba and the Philippines, was Chief of Staff under General Pershing in France, and later commanded the Marine Brigade of the Second Division at Belleau Wood, Bouresches, and Chateau-Thierry. In 1918, he commanded the Service of Supply which was resporsible for all supplies of the A. E. F. so far as we know it was not necessary for Hoxie to do much investigation of the action of either the recorder principle or the reproducer principle, but it undoubtedly did require a deal of ingenuity and skill to make them operate properly in a piece of commercial apparatus. To Professor Miller of the Case School of Applied Science is due the credit for the pioneer work in recording sound waves by the use of suitably mounted small mirrors. His book giving the results of this pioneer work makes fascinating reading and is illustrated with many remarkable photographs of the sound waves from various instruments. The photo-electric cell has been a subject of inquiry, during the last few years, for many able investigators; an explanation of its action, it seemed, might throw much light on the nature of electromagnetic waves as well as on the structure of the molecule. Even as we are writing this, there has just arrived a valuable contribution to the theory and action of photo-electric cells by two of the research workers of the Western Electric laboratories. A photo-electric cell is essentially a two-electrode vacuum tube, one of the electrodes being such a metal as potassium or sodium. If the other electrode is made positive with respect to the potassium, an electron current will flow to it from the potassium whenever the latter is illuminated. The light wave impinging on the surface of the potassium is apparently able to pull out some electrons, which, once through the surface of the potassium, go over to the positive electrode. The number of electrons set free by this so-called photoelectric action, is proportional to the intensity of the light, so that if a light of variable intensity is thrown on the surface of the potassium, the electron current to the anode will correspondingly vary. In the pallophotophone Hoxie has been able to coordinate the work of Miller and that on photo-electricity to create a wonderful soundrecording and reproducing mechanism. By making the mirrors, levers, and diaphragm of extremely small mass, the oscillating light beam sent off from the mirror actually follows even the high-frequency consonant sounds of the voice. The record looks like a black line about one quarter of an inch wide, one side of which has a serrated appearance, due to the peaks of the sound wave reaching out past the edge of the black line. With loud sounds, the pointed projections from the edge of the black line are comparatively long, looking like a lot of fine needle points about one eighth of an inch long, the needle points being at right angles to the edge of the black line. With high pitched sounds the needle points are close together, and with bass notes they are much farther apart. In the reproducing scheme, light shines through this strip of film on to a photo-electric cell; according to the number and size of the serrations on the edge of the black line, a varying amount of light falls on the sensitive cell and so a varying current flows through it. This current goes to the amplifiers and on to the control circuit of the broadcast transmitter. According to those who have heard the reproduction, it is excellent. On several occasions WGY has operated with the pallophotophone film as the voice control and the listeners have been under the impression that the speaker was in the studio of the station. Evi