ELECTRO MAGNETISM.

Bruce Herald, Volume XXV, Issue 2624, 26 October 1894, Page 1 (Supplement)

ELECTRO MAGNETISM.

A Famous Experiment Performed In Very Simple Fashion.

It is a stock feat of every leoturer on {natural science to repeat with the aid of (three somewhat costly appliances — the (magnetic compass,, tho galvanoscope and ,the eleotrio battery — the celebrated experiment of the Danish savant Oersted, showing that a conducting wire brought near •fco a magnetized needle and traversed by on electric current causes such needle to deflect .from its normal position. The importance of this experiment is very great, inasmuch as the faot thereby established was the foundation of the elecjtric telegraph. It .may be repeated in a simpler form, and one may construct with-

out expenditure of time or money the appliances needful for the purpose. The articles required are as follows: A large glass full of water; a champagne glass, or small basin, half full of water, in which" has been dissolved a good handful of common salt; a teaspoon, a fork; some coke, broken into morsels about the size of cherry stones; a sewing needle, a small magnet and, lastly, a strip of zino 7 inches long and three-quarters of an inch wide. Wo will begin with the magnetic compass. Tb procure this rub the needle with the magnet, always in the same direotion, and make it float upon the water in the large glass. This may bo done either by greasing it or by thrusting it through a little piece of paper cut into the shape of a man or of some animal, say a fish. Wo know that one of the points of the needle — say the one which corresponds with the head of the figure — will immediately turn toward the north. Let us now pass to the galvanoscope. This is the apparatus which, by causing the needle to deflect, will indicate to us the presence of the electric current. To procure this we have only to lay the teaspoon across the glass, above the mognetized needle, and in the same direotion. So for, as the reader must admit, all is simple enough, but we now have to construct our battery. To do this we wrap onr little bits of coke in a piece of rag and tie them up in the shape of a sausage, with the handle of the fork in the- middle of it. This coke, plunged into the salt water, will form the positive pole of the battery. Now let us rest the prongs of the fork on one end of the spoon. On the other end-wewill plaoe bne extremity of the zinc, bending it to suit our purpose, letting the opposite extremity dip into the salt water, not, however, touching the little bag of coke. This Will form the negative pole of the battery. An electric current will immediately begin to flow, and you will see the needle place itself at right angles to its former position, immediately returning to it if you remove the zinc strip from the salt Water or otherwise break the circuit.