. Dental electro-therapeutics. be very low in order that a verylarge current may be taken from it. The current strengthcan be augmented by adding cells in series with each ofthose in parallel, or by connecting two equal numbers inparallel and then these two groups in series; by this arrange-ment the current from a number of cells is produced withthe resistance reduced as if from cells in series. Where the main current is installed the cautery from aswitchboard is much more satisfactory, but the resistancemust be constructed to control large currents. BATTERIES 97 Accumulator Battery.—For caute
. Dental electro-therapeutics. be very low in order that a verylarge current may be taken from it. The current strengthcan be augmented by adding cells in series with each ofthose in parallel, or by connecting two equal numbers inparallel and then these two groups in series; by this arrange-ment the current from a number of cells is produced withthe resistance reduced as if from cells in series. Where the main current is installed the cautery from aswitchboard is much more satisfactory, but the resistancemust be constructed to control large currents. BATTERIES 97 Accumulator Battery.—For cautery work and lightingsmall mouth lamps, antrum lamps, and working the dentalengine, this form of battery is one of the most useful. Theprinciple of the accumulator cells has already been cautery two to six cells are connected in parallel andthey need not be of large size, the cells have an E. M. 2 volts each and the current strength will vary accordingto the capacity of the cells. When formed into a battery. Fig. 34.—Accumulator battery for cautery there should be a sliding contact rheostat to turn on thecurrent gradually to suit the size of the cautery or lampthat is being used. Many of the small batteries have acapacity of 50 ampere-hours which under ordinary circum-stances will do service in a dental surgery for a long accumulator battery is superior to a chemical cellbattery for surgical work or light. CHAPTER VBATTERY ACCESSORIES. Current Collector — Milliamperemeter—Rheostats—Rheophores — Elec-trodes—Rheostat for Direct Current from the Main—Resistance for HeavyCurrents—Alternating Current Transformers—High-frequency Currents. Current Collector.—It is usual for most continuous currentvoltaic cell batteries to be constructed with a current col-lector. The object of the collector is to vary the numberof cells to be brought into use at one time to suit the specialcase or to increase the number of cells or collection of cellsby
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