. Electricity in diseases of the eye, ear, nose and throat . oyed, aGerman silver or similar resistance wire of suitablelength is inserted in series with the main means of movable contacts, a branch circuit isformed, through which the drop in voltage and con-sequent current can be varied as desired. 66 ELECTEO-THERAPEUTIC APPARATUS. Before the advent of commercial currents, theordinary series rlieostats were sufficient for thera-peutic purposes, as the batteries were not sufficient-ly strong to admit of a dangerously large high voltage of the commercial current, how-ever
. Electricity in diseases of the eye, ear, nose and throat . oyed, aGerman silver or similar resistance wire of suitablelength is inserted in series with the main means of movable contacts, a branch circuit isformed, through which the drop in voltage and con-sequent current can be varied as desired. 66 ELECTEO-THERAPEUTIC APPARATUS. Before the advent of commercial currents, theordinary series rlieostats were sufficient for thera-peutic purposes, as the batteries were not sufficient-ly strong to admit of a dangerously large high voltage of the commercial current, how-ever, would necessitate so great an amount of re-sistance material as to render the usual types ofrheostat of~unwieldy size, so that, in order to renderthis current available, the shunt controller is moreconvenient. As the purpose of a rheostat is to control thecurrent, it is absolutely immaterial of what materialit consists, so long as it will permit the necessarycurrent to pass without becoming unduly hot, andwill admit of the current being varied by regular. Fig. 52. amounts, but so evenly that the patient does notexperience a shock as the lever passes from one con-tact point to another. As supplied by the makers, the shunt control-lers are marked with a scale of voltages, but, inactual use, such scales serve for comparative meas-urements only and afford absolutely no indicationof the actual drop in voltage; the designers seemingto have overlooked the fact that a branch circuitoperates to lower the resistance of the entire circuit. CONTKOLLERS. 67 Figure 52 shows a combined controller andmeter; and, Figure 53 is a diagram showing theconstruction of the same. jio l/oLT Mains ffEStSTfiNCE x^ dflLl/fJNlC ORUM
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Keywords: ., boo, bookcentury1900, bookdecade1910, booksubjecteye, bookyear1912
