. The practical telephone handbook and guide to the telephonic exchange . Fig. 99 Scale \ Fig. 100 liable to damage by lightning, as a moving charge of electricityhas a property similar to the inertia of a moving body, tendingto move in a straight line, and not deviate, which a chargehas to do when passing through the turns of a coil. A light-ning charge will, when the conditions of the circuit are favour-able, spark across a comparatively great thickness of an in-sulator rather than pass through many turns of wire ; all 104 PRACTICAL TELEPHONE HANDBOOK instruments should, therefore, be provid

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. The practical telephone handbook and guide to the telephonic exchange . Fig. 99 Scale \ Fig. 100 liable to damage by lightning, as a moving charge of electricityhas a property similar to the inertia of a moving body, tendingto move in a straight line, and not deviate, which a chargehas to do when passing through the turns of a coil. A light-ning charge will, when the conditions of the circuit are favour-able, spark across a comparatively great thickness of an in-sulator rather than pass through many turns of wire ; all 104 PRACTICAL TELEPHONE HANDBOOK instruments should, therefore, be provided with some form ofprotector, in which a short and favourable spark gap—usuallythrough air—is arranged. Otherwise the charge will be liableto spark across the silk covering of the wire on the coils, andin so doing fuse the wire itself. A common form of protector is one in which two metal

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Keywords: ., bookcentury1900, bookdecade1900, booksubjecttelephone, bookyear19