Electricity for public schools and colleges . nstrated. A proof-plane of largesize will carry off enough of the charges to affect inductively a previouslycharged electroscope. The fact that in (i.) — electricity would pass from thesole to earth, in (ii.) and (iii.) -I- electricity would do so, and in (iv.) again —electricity would pass away all this can be shown well. Of course we must put the sole to earth at the stages (i.), (iii.), and (iv.),after showing what nature of charge is ready to pass away. § 18. Frictional Electric Machines. I. The glass cyH?iJe?- machine.—The principle of frictio
Electricity for public schools and colleges . nstrated. A proof-plane of largesize will carry off enough of the charges to affect inductively a previouslycharged electroscope. The fact that in (i.) — electricity would pass from thesole to earth, in (ii.) and (iii.) -I- electricity would do so, and in (iv.) again —electricity would pass away all this can be shown well. Of course we must put the sole to earth at the stages (i.), (iii.), and (iv.),after showing what nature of charge is ready to pass away. § 18. Frictional Electric Machines. I. The glass cyH?iJe?- machine.—The principle of frictionalelectrical machines is best understood from a description of oneof the siiiTpler forms. As seen in the figure the essential parts are CH. IV. SIMPLER PHENOMENA OF ELECTROSTATICS 6l as follows. A glass cylinder rotates on a horizontal axis. This ispressed on one side by a rubber made of leather scuffed withhorsehair and faced with silk ; on the surface of the silk is spreada coating of electric amalgam made plastic by mixing it in a. Fig i. powdered form with lard. A silk flap -passes over the cylinderfrom the rubber, descending on the other side to nearly half-waydown. The rubber can be insulated when required. On the otherside to the rubber, a large insulated conductor presents a row offine points to the cylinder. These points nearly touch the glass,and are just below the lower edge of the silk flap. Excepting for these points, the insulated conductor is wellrounded off. When we turn the cylinder, the surface of the glass acquires a+ charge, while the rubber acquires an equal — charge. The +ly excited glass, its charge kept from leakage by theflap of silk, next comes opposite to the conductor with its row ofsharp points. On the conductor it acts inductively, repelling +and attracting — charge. This — electricity is discharged, by con-vection currents of charged air, from the points on to the glass ;so that this latter passes on in its original unexcited conditi
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Keywords: ., bookcentury1800, bookdecade1890, bookpubl, booksubjectelectricity
