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Updated: May 23, 2025
Michael Faraday had worked on this problem for ten years when finally, in 1830, he gave his famous lecture in which he demonstrated, for the first time in history, the principle of electromagnetic induction. He had constructed powerful electromagnets consisting of coils of wire.
The Terrestrians followed their escort high above these great buildings, heading toward the great central tower. In a moment they were above it, and in perfect order the ships of the Venerians shot down to land smoothly, but at high speed. On the roof of the building they slowed with startling rapidity, held back by electromagnets under the top dressing of the roof landing, as Arcot learned later.
One uses fewer Bunsen cells, but they're big and strong, and experience has proven their superiority. The electricity generated here makes its way to the stern, where electromagnets of huge size activate a special system of levers and gears that transmit movement to the propeller's shaft. The latter has a diameter of 6 meters, a pitch of 7.5 meters, and can do up to 120 revolutions per minute."
Of these one furnished the current for the alphabet wheel, one for the figure wheel, and one for the mechanism that took care of the inking and printing on the tape. Callahan made the further innovation of insulating his circuit wires, although the cost was then forty times as great as that of bare wire. It will be understood that electromagnets were the ticker's actuating agency.
Local clocks controlled from a standard clock by electricity have been more successful in practice, and are employed in several towns for example, Glasgow. Behind local dials are electromagnets which, by means of an armature working a frame and ratchet wheel, move the hands forward every minute or half-minute as the current is sent from the standard clock.
"Were these transmitters and receivers made from electromagnets and strips of flat steel, as you told us the other day?" asked Ted. "Yes, their essential parts comprised just those elements an electromagnet and a scrap of flattened clock spring which, as I have explained, was clamped by one end to the pole of the magnet and left free at the other to vibrate over the opposite pole.
The electromotor was invented by Professor Jacobi; it virtually consisted of two disks, one of which was stationary, and carried a number of electromagnets, while the other disk was provided with pieces of iron serving as armatures to the pole pieces of the electromagnets, which were attracted while the electric current was alternately conveyed through the bobbins by means of a commutator, producing continuous rotation.
He found that this law of sympathetic vibration could be repeated electrically and, if desired, from a distance by means of electromagnets placed under a group of piano strings; and if afterward a circuit was made by connecting the magnets with an electric battery, you immediately had the same singing of the keys and a similar searching of each for its own pitch."
The wire between Boston and Fall River had no battery upon it Sunday, and yet there was an artificial current upon it, which increased and decreased in intensity, producing upon the electromagnets in the offices the same effect as would be produced by constantly opening and closing the circuit at intervals of half a minute.
The Little system had perforating apparatus operated by electromagnets; its transmitting machine was driven by a small electromagnetic motor; and the record was made by electrochemical decomposition, the writing member being a minute platinum roller instead of the more familiar iron stylus.
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