aving a range of 300 scale-divisions on eachside, it is necessary to place the tourmaline at a distance ofseveral inches from the disc to keep the amount of the deflec -tion within the limits of the scale. 424. Another application of this instrument is for theexperimental investigation of the… … surface of each of these is of smooth brass ; and one of themis lined wholly, or partially, with sheet zinc, copper, silvei\or other metal to be tested. Thus, to experiment uponthe contact difference of potentials between zinc and copper. * Proceedings of the Royal Society, May 1867. 336…
Electricity · Magnetism
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