. A treatise on electrolysis and its applications to therapeutical and surgical treatment in disease . s lose their maximum intensity From constanl use or from theirproximity to other magnetio influences. These vertical needles are doIliable to the variations which are due to their geographical positions. In another class of galvanometers, the directive influence is not dueto magnetism, but to weight. The magnet may be pivoted like the balan-cing beam of a balance. This short and heavy magnet rests on pivoted knifeedges and a weight is hung under its centre of gravity, bo that a verticalpointi
. A treatise on electrolysis and its applications to therapeutical and surgical treatment in disease . s lose their maximum intensity From constanl use or from theirproximity to other magnetio influences. These vertical needles are doIliable to the variations which are due to their geographical positions. In another class of galvanometers, the directive influence is not dueto magnetism, but to weight. The magnet may be pivoted like the balan-cing beam of a balance. This short and heavy magnet rests on pivoted knifeedges and a weight is hung under its centre of gravity, bo that a verticalpointing needle., made of light aluminum, may be deflected from a central0 on a scale from left to right, or to the opposite according to the direct-ing influence from the current. The magnet beam is surrounded by amultiplied coil above its steel bearings, and another coil of the same lengthbelow these bearings; its movements are so restrained that the oscillationsnever permit the beam to pass outside of these coils. This instrumentwas devised by Lorenzoni and (Fig. 51) is constructed upon the principle. Fig. 51.—Galvanometer for proportional currents. A, heavy magnet pivoted on knife edges likethe beam of a balance; E, weighted ball hung to the magnet to carry the weight below its pivots;B, B, two coils wound around the magnetic field of the pivoted magnet; C, C, wires connecting tin-two coils, to allow the upper one to be removed and to disclose the magnet; Dy needle fixed to themagnetic beam to allow proper reading of the oscillation. that any increase in the magnetic movement of the magnet increases itssensibility, assuming the counterbalance or directing weight to remainconstant. As the vertical component of the earths magnetism exerts acertain directive force upon the magnet, this should be magnetized tosaturation, but its effect is usually not in comparison to the weight ofthe magnet. These instruments are not intended for the indication of 2 70 ELECTROLYSIS. yery small curr
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