. Dental electro-therapeutics. which the studs numbered 1 to 8 are connectedto the positive pole of cells 1 to 8; the negative pole of cellNo. 1 is connected to a separate stud numbered 0, which isconnected with the negative terminal of the battery. Amovable crank handle from the centre of the circle ofstuds is made to fit with perfect metallic contact on thetops of the studs over which it can be moved to makecontact with any of the studs and lead of current from thecells corresponding in number to the stud in contact. Thecrank is connected as shown in the diagram with the positiveterminal of
. Dental electro-therapeutics. which the studs numbered 1 to 8 are connectedto the positive pole of cells 1 to 8; the negative pole of cellNo. 1 is connected to a separate stud numbered 0, which isconnected with the negative terminal of the battery. Amovable crank handle from the centre of the circle ofstuds is made to fit with perfect metallic contact on thetops of the studs over which it can be moved to makecontact with any of the studs and lead of current from thecells corresponding in number to the stud in contact. Thecrank is connected as shown in the diagram with the positiveterminal of the battery. 110 ELEC TRO-PH YSICS The cells being in series it can be readily seen that bymoving the contact metallic crank to a stud, say No. 8,all these cells will be brought into circuit between theterminals marked + and -, and in the same way when thecrank is on No. 4 or No. 2 or any stud it brings into thecircuit the number of cells corresponding to the numbermarked against the particular stud on which it rests. Fig. 41. Plan of current collector. In moving the crank from stud No. 1 to No. 2 and soon over all the studs it increases the E. M. F. and currentby the amount corresponding to that of each individualcell as the crank moves to each adjoining stud. This in-crease is too sudden for the comfort of the patient in thetreatment of sensitive tissues, such as dentine, pulp, orperiodontal membrane. With this form of current collector the cells which areconnected with the studs in the first part of the series are CURRENT COLLECTORS 111 used more frequently and consequently become exhaustedfirst, leaving the latter part unused or much less obviate this difficulty a more complicated collectorhas been devised by which any section of the battery maybe collected. This is a Double Collector. Such a collectordevised by Messrs. Schall & Sons consists of a row of studswhich are connected with the cells by a different arrange- FiG. 42
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Keywords: ., bookcentury1900, bookdecade1910, bookpublisherphiladelphialeafeb
