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Histoire de l'électricité > OERSTED, Experiments on the Effect of a Current of Electricity on the Magnetic Needle, 1820.
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Professor of Natural History, Mr. Jacobsen, Professor of Medicine, and that very skilful chemist, 
Mr. Zeise, Doctor of Philosophy. I had often made experiments by myself ; but every fact which I had 
observed was repeated in the presence of these gentlemen. 
The galvanic apparatus which we employed consists of twenty copper troughs, the length and height 
of each of which was 12 inches; but the breadth scarcely exceeded 2 1/2 inches. Every trough is 
supplied with two plates of copper, so bent that they could carry a copper rod, which supports the 
zinc plate in the water of the next trough. The water of the troughs contained one-sixtieth of its 
weight of sulphuric acid, and an equal quantity of nitric acid. The portion of each zinc plate sunk 
in the water is a square whose side is about 10 inches in length. A smaller apparatus will answer 
provided it be strong enough to heat a metallic wire red hot. 

The opposite ends of the galvanic battery were joined by a metallic wire, which, for shortness 
sake, we shall call the uniting conductor, or the uniting wire. To the effect which 
takes place in this conductor and in the surrounding space, we shall give the name of the 
conflict of electricity. 

Let the straight part of this wire be placed horizontally above the magnetic needle, properly 
suspended, and parallel to it. If necessary, the uniting wire is bent so as to assume a proper 
position for the experiment. Things being in this state, the needle will be moved, and the end of it 
next the negative side of the battery will go westward. 
If the distance of the uniting wire does not exceed three-quarters of an inch from the needle, the 
declination of the needle makes an angle of about 45°. If the distance is increased, the angle 
diminishes proportionally. The declination likewise varies with the power of the battery. 

The uniting wire may change its place, either towards the east or west, provided it continue 
parallel to the needle, without any other change of the effect than in respect to its quantity. 
Hence the effect cannot be ascribed to attraction ; for the same pole of the magnetic needle, which 
approaches the uniting wire, while placed on its east side, ought to recede from it when on the west 
side, if these declinations depended on attractions and repulsions. The uniting conductor may 
consist of several wires, or metallic ribbons, connected together. The nature of the metal does not 
alter the effect, but merely the quantity. Wires of platinum, gold, silver, brass, iron, ribbons of 
lead and tin, a mass of mercury, were employed with equal success. The conductor does not lose its 
effect, though interrupted by water, unless the interruption amounts to several inches in length. 
The effect of the uniting wire passes to the needle through glass, metals, wood, water, resin, 
stoneware, stones; for it is not taken away by interposing plates of glass, metal or wood. 
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