The outlines of physics: an elementary text-book . Fig. 179. I t n226 THE OUTLINES OF PHYSICS In later machines glass disks were substituted for thespheres and cylinders, and a rubber consisting of silk orof undressed leather was used instead of the hand. Itwas soon found that an application of an amalga;m ofsodium to the leather greatly enhanced the activity ofthe machine. Figure 180 shows the usual form given tothese frictional machines, which, to distinguish them fromother types, are called plate machines. The essentialparts of such instruments are:. Fig. 180. (1) A glass plate mounted upon
The outlines of physics: an elementary text-book . Fig. 179. I t n226 THE OUTLINES OF PHYSICS In later machines glass disks were substituted for thespheres and cylinders, and a rubber consisting of silk orof undressed leather was used instead of the hand. Itwas soon found that an application of an amalga;m ofsodium to the leather greatly enhanced the activity ofthe machine. Figure 180 shows the usual form given tothese frictional machines, which, to distinguish them fromother types, are called plate machines. The essentialparts of such instruments are:. Fig. 180. (1) A glass plate mounted upon a cylindrical axis andturned by means of a crank. (2) A pair of leather-faced rubbers, r, which clamp themachine near the periphery of the glass. (3) A prime conductor, as it is called, which is a metalbody, usually cylindrical in shape with rounded ends, uponwhich the charge from the glass is gathered by means ofa pair of metal combs, the teeth of which come as nearlyas possible into contact with the electrified plate at a point180° distant from the rubbers. The prime conductor, 0,and also the clamp are supported upon glass posts. Thepost which carries the rubbers is generally capped by ahollow brass ball, as shown in the figure. CONDUCTORS AND NON-CONDUCTOES 227 That the action of such a machine is similar to that ofa glass rod rubbed by hand with a silk handkerchief,may be shown by testing the character of the charge uponthe prime conductor, and upon the ball, which is in contactwith the clamp. It will be found that the prime conductoralway
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Keywords: ., bookcentury1800, bookdecade1890, bookpublishe, booksubjectphysics
