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6. Soon after this, a Frenchman named Du Fay showed that substances filled with different kinds of electricity attract each other. Both these men thought that electricity was a fluid which was created by the rubbing, and which was not in bodies at other times.

7. But about the middle of the last century Benjamin Franklin began to pay attention to these experiments in electricity, and to make experiments himself. He soon saw clearly that all bodies have more or less electricity in them, which the rubbing only brings out. Franklin began to consider how many of the effects of lightning were the same as those of electricity.

8. Lightning travels in a zigzag line, said he, and so does an electric spark; electricity sets things on fire, so does lightning; electricity melts metals, so does lightning. Animals can be killed by both, and both cause blindness. Electricity always finds its way along the best conductor, or the substance which carries it most easily, so does lightning; pointed bodies attract the electric spark, and in the same way lightning strikes spires and trees and mountaintops. "Is it not probable," thought he, "that lightning is nothing more than electricity passing from one cloud to another, just as an electric spark passes from one substance to another?"

9. Franklin's idea was, that if he could send an iron rod up into the clouds to meet the lightning, it would become charged with the electricity which he believed was there, and would send it down a thread attached to it, so that he might be able to feel it. He took, therefore, two light strips of cedar fastened crosswise, upon which he stretched a silk handkerchief tied by the corners to the ends of the cross; and to the top of this kite he fixed a sharp-pointed iron wire more than a foot long. He then

put a tail and a string to his kite; and at the end of the string near his hand he tied some silk (which is a bad conductor), to prevent the electricity from escaping into his body. Between the string and the silk he tied an iron key (the metals being the very best conductors), in which the electricity might be collected.

10. When his kite was ready he waited eagerly for a heavy thunder-storm; and, as soon as it came, he went out with his son to the commons near Philadelphia, and let his kite fly. It mounted up among the dark clouds; but at first no electricity came down, for the string was too dry to conduct it. But by and by the heavy rain fell, the kite and string both became thoroughly wet, and the fibers of the string stood out as threads do when electricity passes along them.

11. As soon as Franklin saw this, he knew that his experiment had succeeded: he put his finger to the key, and drew out a strong bright spark,-the most welcome rap upon the knuckles that any man ever received. Franklin soon put his discovery to practical use. Whenever you see a lightning-rod guarding a building from destruction, remember that we owe that invention to him and to his kite-flying.

12. Franklin proposed to fix on the highest points of edifices upright rods of iron made as sharp as a needle, and gilded to prevent rusting, and extending down the outside of the building into the ground, or down round one of the shrouds of a ship, and down the side till it reaches the water.

13. It has since been found that rods of copper form the best conductors. These are now set into the masts of ships, passing down which they pierce the keel, and are fastened underneath by copper bolts in contact with the water.

Benjamin Franklin (7), patriot, statesman, author, philosopher, and scientist, was born in Boston, on January 17, 1706, and died April 17, 1790. He took an active part in the struggle for American independence, and was sent as our Minister to France. It was mainly by his efforts that the aid and sympathy of France were obtained for the American Colonies.

From what is the word "electricity" taken (1)? How can we excite electricity in a simple way (3)? How and when was the first electrical machine made (4)? What was substituted for the sulphur globe (4)? What do substances filled with different kinds of electricity do (6)? Who discovered that electricity is in all bodies (7)? What did Franklin begin to consider (7)? At what conclusions did he arrive (9)? How did he experiment (9)? What was the result of his experiments (10)? What form the best conductors (13) ?

LESSON LXXVIII.

6. çîr' euit; n. a continuous 10. Ŏp' ēr ā' tor; n. one who electrical communication beworks an instrument. tween the two poles of a bat- 11. ú′ní són; n. agreement. tery. 14. elï'ent; n. one who applies to a lawyer for advice.

9. de prèssĕş; v. presses down; lowers.

14. ae count'ĕd; v. considered.

Electricity. Part II.

1. Only a few months before Franklin died, a new fact was discovered about electricity by Galvani, professor of anatomy at Bologna. One day as Madame Galvani was skinning frogs for a soup, one of Galvani's assistants was working an electrical machine near her. Just as the flow of electricity was going on rapidly, this young man happened to touch a nerve of the leg of one of the frogs with a dissecting-knife; and to his great surprise the leg began to move and struggle as if it were alive.

2. Madame Galvani was so much struck by this that she told her husband of it; and he repeated the experi

ment many times, and found that whenever the flow of electricity from the machine was brought near the nerve of the frog's leg it produced convulsions. This discovery of Galvani soon became spoken of far and wide, under the name of galvanism.

3. Among the celebrated men who were attracted by it was Volta, professor of natural philosophy at Pavia. Not satisfied with merely reading about Galvani's experiments, he tried them himself; and he began to suspect that the electricity was produced by the metal, acted on by the moisture of the flesh. As a result of his experiments Volta discovered that two different metals when joined together in contact with moisture, and separated from other substances, produce a current of electricity.

4. This may easily be tried in its very simplest form. If you take a piece of copper and a piece of zinc, placing one above your tongue and the other below it, you will feel nothing remarkable so long as the metals are kept separate; but as soon as you let them touch each other at the ends a tingling sensation will pass through your tongue, proving to you that an electrical current is passing between the metals. If you put the zinc under your upper lip, so that the copper may remain outside, you may, perhaps, even see a slight flash when the two metals meet.

5. Volta found that some acid put in the water between the two metals greatly increased the strength of the electricity. We know now, what Volta did not know, that a change is going on between the zinc and the acid water; but we do not yet know what electricity itself is. Such was Volta's discovery, and we owe to it all the powerful voltaic batteries with which our most valuable experiments are now made.

6. Franklin had proved the real action of electricity,

had shown it to be the same as lightning, and had brought it down from the sky. Galvani had proved its existence in animals, and led the way to Volta's discoveries; and Volta had produced it in such enormous quantities by means of two metals and acid water, that he could keep up a constant flow of electricity, which would travel any distance so long as the circuit was not broken.

7. Here, you will see, was the first step toward the electric telegraph. Ever since Volta showed that an electric current can be sent for any distance along a wire the two ends of which are joined to the poles of a battery, scientific men had thought it might be possible to use this current for making signals at a distance. But there was always the difficulty of how to make the signs at the other end.

8. An electric telegraph was patented by Professor Wheatstone and Mr. Cooke in 1837; and during the same year Dr. Steinheil, of Munich, and Professor Morse, an American, both invented telegraphs.

9. Telegraph stations are connected by an electrified wire, the ends of which enter the ground, the earth (which is a good conductor) completing the circuit. When one operator wants to send a message to another, he alternately depresses and raises a button at his end of the wire. This action alternately breaks and completes the electric circuit, and this breaking and completing of the circuit is instantly perceptible at the other end of the wire. The different letters of the alphabet are indicated by the number and length of these interruptions of the circuit.

10. Some machines record the dots and lines of the telegraphic alphabet on paper tapes, and some even print the message in letters; but a skillful operator becomes so accustomed to the various sounds that the clicking of the

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