United States or Niue ? Vote for the TOP Country of the Week !


The basis of his telephone was still the disk or diaphragm which would vibrate when the sound-waves of the voice were thrown against it. Behind this were mounted various kinds of electro-magnets in series with the electrified wire over which the inventor hoped to send his messages. For three years they labored with this apparatus, trying every conceivable sort of disk.

His forefinger indicated an ingenious but now twisted and tangled series of minute wires and electro-magnets in the delicate mechanism now broken open before us. Delicate brushes led the current into the wheel. With another blow of the axe, Garrick disclosed wires running down through the leg of the table to the floor and under the carpet to buttons operated by the man who ran the game.

Without the improved electro-magnets and the relay of Professor Henry, Morse had not yet even the basic ideas upon which a telegraph to operate over considerable distances could be constructed. But Morse was possessed of Yankee imagination and practical ability. He was possessed of a fair technical education for that day, and he eagerly set himself to attaining the means to accomplish his end.

He brought Bell to his house and showed him what Helmholtz had done how he had kept tuning-forks in vibration by the power of electro-magnets, and blended the tones of several tuning-forks together to produce the complex quality of the human voice. Now, Helmholtz had not been trying to invent a telephone, nor any sort of message-carrier.

A suggestion contained in Sir Charles Wheatstone's paper, that "a very remarkable increase of all the effects, accompanied by a diminution in the resistance of the machine, is observed when a cross wire is placed so as to divert a great portion of the current from the electro-magnet," had led the lecturer to an investigation read before the Royal Society on the 4th of March, 1880, in which it was shown that by augmenting the resistance upon the electro-magnets 100 fold, valuable effects could be realized, as illustrated graphically by means of a diagram.

A flat form of the ordinary Siemens H armature, E, revolves between the poles, P, of the electro-magnets, M, which are connected by means of the base plate, I. The brass cross-bar, G, carries the top bearing of the spindle, S, and prevents the magnet poles from being drawn together.

With a given energy expressed in watts, we can arrange a quantity of wire and iron to produce a certain quantity of work; the smaller the quantity of material employed, and the larger the return for the energy put in, the greater is the total efficiency of the machine. Powerful electro-magnets, judiciously arranged, must make powerful motors.

The exciting current was at first obtained from a small permanent magneto machine; but it was afterward found that the machine could be made self-exciting. Soft-iron electro-magnets, after being once magnetized, remain slightly magnetic. This will produce a weak current in the revolving armature which is turned into the magnet coils.

The most important of these results consisted in this, that the electromotive force produced in a "shunt-wound machine," as it was called, increased with the external resistance, whereby the great fluctuations formerly inseparable from electric arc lighting could be obviated, and thus, by the double means of exciting the electro-magnets, still greater uniformity of current was attainable.

If the airplane tilts to one side or the other, the mercury will try to keep its level and will immediately flow to the high side of the bore. At each end of this mercury tube there are electrical contact points. As one becomes submerged in the mercury by a tilting of the plane, a connection is made whereby two electro-magnets are energized on that side.