Lives of the electricians

by William T. Jeans

It may here be explained that Ohm was another eminent electrician, whose immortal discovery was at first consigned to neglect. His work, expounding the principle now known as Ohm’s law, was published at Berlin in 1827; but was not translated into English till 1841. It is said that for the first ten years after the publication of his work, only one continental author admitted or confirmed his views, but between 1836 and 1841, scientific men began to appreciate the value of his researches. Wheatstone was one of them. In 1841 Ohm was presented with the Copley gold medal of the Royal Society, when the President said: “Ohm has shown that the usual vague distinctions of intensity and quantity have no foundation, and that all the explanations derived from these considerations were perfectly erroneous. He has demonstrated both theoretically and experimentally that the action of a circuit is equal to the sum of the electromotive force (E. M. F.) divided by the sum of the resistances, and that whatever the nature of the current, whether voltaic or thermo-electric, if this quotient be equal, the effect is the same.”

Mr. George Cruikshank afterwards published a statement confirming the claims of Professor Wheatstone. He said that having been a friend of Professor Wheatstone, he wished to state that “the discovery of the telegraph arose from the circumstance that when first appointed lecturer at King’s College, he had seven miles of wire in the lower part of the building which abuts upon the river Thames, for the purpose of measuring the speed of lightning or the electric current. Upon one occasion when explaining his experiments to me, he said: ‘I intend one day to lay some of this wire across the bed of the Thames and to carry it up to the Shot Tower on the other side, and so to make signals.’ This was, I believe, the first idea or suggestion of a submarine telegraph. We are also indebted to him for the electric bell, for long before the telegraph came before the public, in explaining the machine to me, he said that as it was possible that one party might be asleep at one end of the wire, he had so arranged the working that the first touch should ring the bell at the other end, even if thousands of miles apart. This, it will be admitted, is an important part of the discovery.”

Next to the mechanism by which electric signals are made intelligible, one of the most important inventions is that by which an electric current is enabled to renew its strength as it goes along a great length of wire. The apparatus used for this purpose is called a relay, and the first man to publish an account of it was Prof. Wheatstone. Its mechanism is delicate and sometimes complex, but its principle can be easily understood. Most people understand that when a railway train has run a great distance, the engine requires to take in water or coal, and for that purpose it sometimes moves on to a siding in connection with which there is a constant supply of water or coal. In like manner, on long telegraphic lines electric batteries are kept in readiness at certain distances; but if they were connected with the main line it is obvious that their contents would be uselessly dissipated. They are therefore kept in a kind of siding, and are only temporarily connected with the main line for the purpose of replenishing a passing current. In the case of a railway the service of a pointsman is often needed to connect and disconnect a siding; but in the case of the telegraph the connecting link between the replenishing battery and the main line is made self acting. This is effected by the use of that property of electricity which causes an electrified wire to attract to it an adjacent piece of wire or iron. In the relay a needle or lever is so adjusted that when a feeble current comes along the main line, it attracts the needle of the relay line, and by means of this connection a fresh current from the local battery flows on to the line, and does the work which the original current had become too feeble to accomplish. This invention was embodied in the first patent of Professor Wheatstone; and Professor Henry, of New York, has sworn to the fact that when he was in London, in 1837, Professor Wheatstone showed him in King’s College, early in April, his method of bringing into action a second galvanic current by means of the deflection of a needle. Professor Bache was also present.

The first patent was taken out in June, 1837, in the joint names of Cooke and Wheatstone. Their telegraph had five wires and five needles. The guiding principle of their signalling apparatus was that a current of electricity on passing along a wire deflected the magnet or needle. Professor Wheatstone candidly acknowledged that he was not the discoverer of that principle; but it was he who discovered the practical basis upon which the wires and magnets should be adjusted so as to produce the desired effects. He arranged in a row five needles like those in a mariner’s compass; and when a current of electricity was sent along one of the wires the needle attached to it could be deflected to the right or left at the will of the sender. In the original form of the receiving instrument the needle was worked or deflected upon the face of a dial, upon which the letters of the alphabet were so arranged that any letter could be indicated at will by the sender making two of the deflected needles converge towards the desired letter. Any person could manipulate this instrument, as there was no secrecy or code involved in its signals.

FACE OF WHEATSTONE’S FIRST TELEGRAPH INSTRUMENT.

A glance at the illustration will show the simplicity of this apparatus. The objection to it was that it required five wires to transmit the signals and a sixth wire to bring back the electricity after it had done its work. But the only other electric telegraph then announced in England required twenty-six wires; and it is in comparison with previous efforts that the first Wheatstone instrument should be judged. It is a curious fact that just fifty years after the invention of this instrument with six wires, a new system of telegraphing was tried by which six messages could be sent almost simultaneously on one wire, either all in one direction, or part of them in one direction and the remainder in the opposite direction.

The first electric telegraph designed by Wheatstone was laid down on the North Western Railway between Euston Square and Camden Town Stations, a distance of a mile and a half. It was first worked on the evening of July 25th, 1837, which may be considered as the birthday of the electric telegraph in England. Let us see how and where it came to pass. Late in the evening, in a dingy little room near the booking office at Euston Square, by the light of a flaring dip candle, which only illuminated the surrounding darkness, sat the inventor with a beating pulse and a heart full of hope. In an equally small room at Camden Town Station, where the wires terminated, sat Mr. Cooke, his co-partner, and among others two witnesses well known to fame, Mr. Charles Fox and Mr. Stephenson. These gentlemen listened to the first word spelled by that trembling tongue of steel, which will only cease to speak with the extinction of man himself. Mr. Cooke, in his turn touched the keys and returned the answer. “Never,” said Professor Wheatstone, “did I feel such a tumultuous sensation before, as when all alone in the still room I heard the needles click, and as I spelled the words I felt all the magnitude of the invention now proved to be practicable beyond cavil or dispute.”

Nevertheless the public treated it with indifference; the directors of the railway soon gave it notice to quit, and one of them even denounced it as “a new-fangled thing.”

The next line of telegraph was made on the Great Western Railway. In July, 1839, a line of wires was laid from Paddington to West Drayton, a distance of thirteen miles. An arrangement had been made between the Railway Company and Messrs. Cooke and Wheatstone to the effect that within a certain number of months after the telegraph had been laid and efficiently worked between these two places, the Railway Company might call on the patentees to give them a license for the whole of the line, and the Railway Company had the power to construct a telegraph all the way from Bristol to London for a certain number of years; but the work not being done within the prescribed time, the agreement became void, and for some time the telegraph did not extend beyond Slough—a distance of seventeen miles. From the first the line to West Drayton worked satisfactorily. For the purpose of testing whether it could be relied on, it was used for nearly two months to communicate to Paddington the moment of the passing of the trains at West Drayton and Hanwell, and it was found to answer admirably. The cost of making that line was from £250 to £300 a mile, including the charge for station instruments. At first the wires placed in a tube were put underground, but it was soon found better to have them above ground, where they were less liable to injury from wet.