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an eminent man of action and scholarship, to head our reform, some happier Sumner, some Horace Mann. We want one for every State in the United States. We want a village Gladstone for every town. None such : shall rest inglorious.
By PROF. E. A. DOLBEAR,
In the old legend, the Goddess of War is said to have sprung full-armed from the brain of Jupiter, but it is only in mythology that one may look for an event without something of a history. No important invention has been the work of a single man, and the speaking telephone has a history which is much longer than it appears to have had, seeing that it is but a year or two old. It is my intention to trace briefly the various discoveries that have led up to this invention, giving them in their chronological order so far as possible. The instrument is exceedingly simple, there being but three essential parts to it, namely, a magnet, a coil of wire, and a small plate of tin or iron. In its action there are involved some of the laws of electricity, of magnetism, and of sound. Of the first of these, we are all familiar with the story of Franklin and his kite, of Galvani and the frogs' legs, and of Volta and Sir Humphrey Davy, who did such great things with a galvanic battery about the beginning of this century. In 1820 Oersted discovered that a magnetic needle was deflected by a current of electricity in a neighboring wire; and in 1825 Sturgeon learned how to make an electro-magnet. Henry, in 1829, increased the lifting power of the magnet a hundred-fold and more by insulating the wire, and used such battery and magnets in the first e!ectromagnetic telegraph. Morse merely improved the mechanism and invented an alphabet. Page made the first electric telephone; and in 1863 Reiss undertook to make a telephone to convey articulate speech. He did not succeed, but mainly for reasons which I will state by and by.
Let me speak a little of sound, as consisting of vibrations in the air or other sound-conductor. Hold a piece of paper rather tightly in front of the mouth, and speak or sing against it, and you will feel it vibrate; the same would be true if you take a piece of sheet-iron or wood, — the iron moves back and forwards, varying in rapidity with the pitch and in character with the kind of a sound. Suppose that a piece of iron be fixed to a membrane and this mounted in front of an electromagnet, and you should make the membrane to vibrate, it is evident that this movement would generate corresponding currents of electricity in the conductor; and if a suitable magnet was prepared to be affected by these vibrations of the current, vibrations like the first will be set up, and given out to the air. This was Prof. Bell's invention, as exhibited at Philadelphia, - a very unexpected invention, and rightly very highly spoken of.
The next invention which belongs in the category is one of my own, and it consists, as before said, of three parts, and to understand its action we must go back to an experiment of Faraday's in 1832. Here is a magnet, a coil of wire, and a galvanometer; there the magnet is thrust into the coil, the needle moves showing that electricity has been developed ; the same thing happens if I permit a piece of iron to approach the magnet while the coil of wire is about the pole of the latter, - this is called magneto-electric induction. When the plate of the telephone vibrates, it acts upon the magnet and the coil in like manner, and the electricity affects the magnet of the other instrument to increase and decrease its attractive power, and so makes its plate to vibrate as the first plate did. It will be seen that this instrument is unlike all the others, in that it dispenses with the battery; and both instruments are alike. This instrument which is now in use so extensively is, I repeat, my invention, and was made at a time when I had no knowledge of the structure of Bell's device.
Comparing this telephone with that of Reiss, it is seen that the latter had nothing for his receiving-magnet to act upon, - no armature. Take a Reiss telephone, and let it be connected with a proper receiver, and it makes a very loud telephone ; indeed, I have such a one, which I will now exhibit.
We have lately heard very much of the microphone, - a new name given to an old invention of Edison's. I have a modification of this which I have been using for a good while, and which I wish to show to you, hoping that you can all hear what my assistant may say to you. There are many devices for doing this kind of work, but the public is already losing its interest in the telephone as a novelty. The phonograph has supplanted it, and directly we shall forget that, and, like the old Greeks, be looking for some new thing.