Davis's manual of magnetism : including galvanism, magnetism, electro-magnetism, electro-dynamics, magneto-electricity, and thermo-electricity . thickness,and the cup A with the other pole (say the positive).The current will then be divided into two portionsvery nearly equal, both flowing in the same direction,and at the same distance from the magnet, M, butone below and the other above it. Now, if thehorizontal portions of the wire alone acted on theneedle, it would remain unaflected; but it will befound to be deflected to a considerable extent by thecurrent w^hich is descending in the vertic
Davis's manual of magnetism : including galvanism, magnetism, electro-magnetism, electro-dynamics, magneto-electricity, and thermo-electricity . thickness,and the cup A with the other pole (say the positive).The current will then be divided into two portionsvery nearly equal, both flowing in the same direction,and at the same distance from the magnet, M, butone below and the other above it. Now, if thehorizontal portions of the wire alone acted on theneedle, it would remain unaflected; but it will befound to be deflected to a considerable extent by thecurrent w^hich is descending in the vertical portionof the wire near A, and ascending in that below B,as these conspire in their influence. 160. Horizontal Galvanometer. — If the wireis carried many times around the needle, as in , the power of the instrument is much increased,as each turn of the wire adds its influence ,* providedthe wire is not so long, or of so small a size, as to beunable to convey the whole of the current. Tha UPRIGHT GALVANOMETER. 101 thus becomes a delicate test of the pres-ence of a current of electricity. The coil of wire is Fig;. supported on a tripod stand, with leveUing screws; the ends, C and D, of the wires being connected with the screw cups, A and B. i^>. 55. 1^1- Upright Galvanometer.— In this instrument, represented inFig. 55, both the coil of wire andthe needle are placed in a verticalposition, the north pole being madea little heavier, in order to keepthe magnet perpendicular. Whena current is passed through thecoil, the deflection is towards ahorizontal position. The needle ismade of large size, for the purposeof exhibiting the deflections beforean audience.
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Keywords: ., bookcentury1800, bookdecade1850, booksubjectmagnetism, bookyear18
