CALLING ALL NATIONS -- 1941

WONDERS OF RADIO

Page 425 (cont.)

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By Ellison Hawks, writing in the Popular Science Mechanical Encyclopedia, Popular Science Publishing Company, Inc., New York, 1941, p. 423 - 459.

only exceeding small effects can be produced by the most powerful electrical effect at the point of excitation. Had we the means which could stand in the same relation to electricity that the eye stands to light, nothing would prevent our telegraphing through the earth without conducting wires, but it is not possible that we shall ever attain this end."

The next step forward was made by S. F. B.Morse, whose successful experiments in connection with the telegraph we have already described. A few months after he had obtained his grant from the U.S. Government (in 1843) for the installation of his experimental telegraph line between Washington and Baltimore, he endeavored to arouse interest in his invention by giving a public demonstration of the fact that an electric current will travel as well along a cable laid through water as along an air line. On the night of October 18, 1842, he laid insulated wires between Governor's Island and Castle Garden, New York, a distance of about a mile.

[For more on Morse click here]

At daybreak on the following morning he prepared to give his demonstration and had transmitted three or four characters when communication was suddenly interrupted owing to one of several vessels lying along the line of the submerged cable raising the cable on her anchor. Not understanding what they had hauled on board, and finding no end to the cable, the sailors hauled about 200 ft. on deck, cut it off, and took it away with them!

With the jeers of the disappointed spectators ringing in his ears, Morse "immediately devised a plan for avoiding such an accident in the future, by so arranging my wires along the banks of the river as to cause the water itself to conduct the electricity across." He laid a wire along each bank, connecting one wire to the transmitting key and a battery and the other wire on the opposite bank, to a galvanometer, the ends of both wires being fastened to copper plates sunk in the river (Fig. I). The experiment was successful and later he was able to transmit over the Susquehanna River with complete success for a distance of nearly a mile.

Editor's note: Do you see what is happening in the illustration above? This is transmitting by conduction. Morse used the water of the river to conduct a signal. No wires in between the sending points or plates, just water to act as the transmission media. I suppose this should be possible today. T.F.

SIGNALING ACROSS THE TAY

About this time, J. B. Lindsay was experimenting on similar lines at Dundee, Scotland, and perfected a system of radio communication by conduction, signaling across the Tay over two miles. We shall not consider his work in detail, but need only say that it had the effect of interesting W. H. Preece in the subject of radio communication. In 1870 Preece was appointed Divisional Engineer to the English General Post Office and later (1892) became Engineer-in-Chief. In that (please see the next page)

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