. Electricity in diseases of the eye, ear, nose and throat . cuit werebroken and completed while he was under treat-ment. A variety of this cut-out contains a second mag-net that operates to open the circuit if the currentshould rise too high, but it is not yet adapted tomedical uses. Lamps.—An ordinary electric lamp, in serieswith the main circuit, forms at once a satisfactoryand inexpensive means of reducing the commercialcircuit to a suitable strength for the physiciansneeds. In effect, it is simply a rheostat of fixedcapacity, but it has the further advantage of effect-ually opening the ci
. Electricity in diseases of the eye, ear, nose and throat . cuit werebroken and completed while he was under treat-ment. A variety of this cut-out contains a second mag-net that operates to open the circuit if the currentshould rise too high, but it is not yet adapted tomedical uses. Lamps.—An ordinary electric lamp, in serieswith the main circuit, forms at once a satisfactoryand inexpensive means of reducing the commercialcircuit to a suitable strength for the physiciansneeds. In effect, it is simply a rheostat of fixedcapacity, but it has the further advantage of effect-ually opening the circuit if it should burn out and ofacting as a pilot light to show that a current is pass-ing through the apparatus. RECTIFIERS. In order to obtain a direct current from thecommercial alternating circuit, some form of recti-fying apparatus is needed. The following are employed in medical work: KECTIPIEES. 69 Rotary.—In this form a motor, driven by thecommercial current is used to drive a miniaturedynamo, which produces the current required. In. Fig. 55.—A Motor Generator. some forms of this apparatus, the two windings aresuperimposed on the same shaft. The combinedform is usually known as a motor-generator. Electrolytic.—The electrolytic rectifier owesits value to the curious property possessed bycertain gases and metals of conducting a current bet-ter in one direction than in the other. As ordinarilymade, this rectifier consists of an aluminum and aniron plate immersed in an ammonium phosphatesolution. On connecting these electrodes to an al-ternating circuit, the current will flow only from theiron to the aluminum; the reverse wave being sup-pressed—and an intermittent current results. 70 ELECTRO-THERAPEUTIC APJPARATUS. In actual practice, however, the action is notinstantaneous and there is often a small negativewave of sufficient magnitude to affect the properworking of an ic-ray tube. In order not only to re-duce this to a minimum, but also to utilize th
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Keywords: ., boo, bookcentury1900, bookdecade1910, booksubjecteye, bookyear1912
