Text-book of medical and pharmaceutical chemistry . rrent in the wire, and upon the proximity of this to theneedle. If the conductor be returned upon the under side ofthe needle, so that the current shall flow in the opposite direc-tion, the needle will be still more deflected, and in the same MAGNETISM. 57 direction. By using a number of turns of insulated wire, /. e.,forming a coil, as shown in Fig. 21, a multiplication of thedeflecting power will be obtained. The plane of the coil,must coincide with the plane of the earths magneticmeridian. If this needle be suspended or mounted upon a dial
Text-book of medical and pharmaceutical chemistry . rrent in the wire, and upon the proximity of this to theneedle. If the conductor be returned upon the under side ofthe needle, so that the current shall flow in the opposite direc-tion, the needle will be still more deflected, and in the same MAGNETISM. 57 direction. By using a number of turns of insulated wire, /. e.,forming a coil, as shown in Fig. 21, a multiplication of thedeflecting power will be obtained. The plane of the coil,must coincide with the plane of the earths magneticmeridian. If this needle be suspended or mounted upon a dialhaving a scale of degrees marked upon it, the number of degreesthrough which the needle swings under the influence of a certaincurrent passing through the coil, will indicate the strength of thecurrent. In other words, such an instrument would be a gal-vanometer or electro-meter. If the scale is sp divided as to read the current strength inamperes or milliamperes, the instrument would then be knownas an ampere-meter or milli-ampere-meter. Fig.
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