Radio Broadcast (May-Oct 1922)

208 Radio Broadcast rapidly. Over the bow of the boat we made water connection by a metalHc plate, and behind the boat we trailed an insulated wire, with a float at the end carrying a metallic plate so as to bring these two terminals about loo feet apart. 1 then took another boat and sailed off. In this boat we had the same arrangement, but with a telephone in the circuit. In the first boat, which was moored, 1 kept a man making signals; and when my boat was near his 1 would hear those signals very well — a musical tone, something of this kind: tum, turn, tum. 1 then rowed my boat down the river and at a distance of a mile and a quarter, which was the ""^^i furthest distance 1 tried, I could still J^^^: distinguish those signals." i^^^B He added, in our discussion, that f^^^S^ one of the boats that he used was )^HH1 near Chain Bridge while his own boat ^^^P was, at the conclusion of the experiments, at the Washington Monument. And at the time of his experiments he pointed out the practicability, since " most of the passenger steamships have dynamo engines and are electrically lighted," of each vessel trailing a wire a mile or so long duly charged, and attached to a telephone. "Then," he said, "your dynamo or telephone end would be positive and the other end of the wire trailing behind would be negative. All of the water about the ship will be positive within a circle whose radius is one-half the length of the wire. All of the water about the trailing end will be negative within a circle whose radius is the other half of the wire. ... It will be impossible for any ship or object to approach within the water so charged in relation to your ship without the telephone telling the whole story to the listening ear. Now, if a ship coming in this area also has a similar apparatus, the two vessels can communicate with each other by their telephone. If they are enveloped in a fog, they can keep out of each other's way. The matter is so simple that 1 hope our ocean steamships will experiment with it." It is only to be added that these land and water experiments of Doctor Bell without question were factors in the success of Mr. — later Sir — William Preece in England. His first experiment was made in 1882. In that year in a public address, he said, " The discovery of the telephone has made us acquainted with many strange phenomena. It has enabled us, amongst other things, to establish beyond a doubt the fact that electric currents actually traverse the earth's crust. The theory that the earth acts as a great reservoir for electricity may be placed in the physicist's wastebasket. . . . Telephones have been fixed upon a wire passing from the ground floor to the top of a large building (the gas pipes being used in place of a return wire), and Morse signals, sent from a telegraph office 250 yards distant, have been distinctly read. There are several cases on record of telephone circuits miles away from any telegraph wires, but in a line with the earth term^^^^ inals, picking up telegraphic signals; and when an electric-light system ^^^-^ uses the earth, it is stoppage to all telephonic communication in its neighborhood." Mr. Preece then WH^BI describes one of the first of all his ex^^W^ periments, which was made, it is to be noted, nearly five years after those described above of Doctor Bell. Simply, this experiment, in March, 1882, successfully linked up the Isle of Wight with Southampton when the cable between that island and Southampton broke down. His complete circuit, including the water, started from Southampton, ran to Southsea Pier, 28 miles; across the sea, 6 miles; Ryde through Newport to Sconce Point, 20 miles; across the water again, i| mile, thence from Hurst Castle back to Southampton, twenty-four miles. "With a buzzer, a Morse key, and 30 Leclanche cells at Southampton," he says, "it was quite possible to hear the Morse signals in a telephone at Newport, and vice versa. Next day the cable was repaired, so that further experiment was unnecessary." Since those early days, while on one hand it becomes more and more apparent that the radio art would have been infinitely harassed in its origin and development without the telephone, it has also become apparent that the relationship of earth characteristics and those of the sea, must sooner or later have been given just such attention as Doctor Bell gave, and encouraged others to give, to them. There is good ground for saying that these experiments fathered many perfections in earth telegraphy, including the TPS work used in the main during the war by both the Allies and the Germans for intercepting messages, notably telephone messages. But, it is also to be noted that ground methods do not permit of the use of high frequencies, do not employ tuned cir