The practical telephone handbook and guide to the telephonic exchange (1906)
Poole, Joseph · New York, Macmillan Co. · leaf 481
werfully on the astaticsystem, and a shorter length of wire is required for the samenumber of turns. The beam of light also forms a very longand weightless index, which moves twice as far as an actualfixed index of the same length, by reason of the law of reflection. &Arsonval… … ELECTRICAL MEASUREMENTS 453 direct to the proper point on the scale without unnecessaryvibration about that point) and its freedom from the effectsof external vibration and magnetic influences. It is not,however, so sensitive, and has not the all-round usefulnessof the Kelvin instrument. Fig. 428…
Telephone
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