Davis's manual of magnetism : including galvanism, magnetism, electro-magnetism, electro-dynamics, magneto-electricity, and thermo-electricity . n into an inclined one; and when it reaches avertical position, its edge resting on the ribbon coil,they are no longer felt. Similar phenomena are pre-sented when the flat spiral has a sufficiently largecentral opening to allow the wire coil to pass withinit; no shocks being obtained when their axes are atright angles to each other. If the diameter of thewire coil is considerably less than that of the open-ing, and it is placed in a horizontal positio
Davis's manual of magnetism : including galvanism, magnetism, electro-magnetism, electro-dynamics, magneto-electricity, and thermo-electricity . n into an inclined one; and when it reaches avertical position, its edge resting on the ribbon coil,they are no longer felt. Similar phenomena are pre-sented when the flat spiral has a sufficiently largecentral opening to allow the wire coil to pass withinit; no shocks being obtained when their axes are atright angles to each other. If the diameter of thewire coil is considerably less than that of the open-ing, and it is placed in a horizontal position withinthe spiral, the shocks are somewhat stronger whenit is near the side than when in the centre. 409. The interposition of any good conductor ofelectricity between the fine wire coil and the one connected with the bat-tery nearly neutralizes theshocks. The coils beingarranged as represented inFig. 169, interpose a slipof wood or a plate of glassbetween A and W, andthe sliock will be the sameas if air only will be the case with any non-conductor of elec-tricity. Now, interpose a plate of metal, for instance, Fis:. 256 DAVISS MANUAL. lead or zinc, one tenth of an inch thick, and as broadas the coils. The sliock will be so much reduced asto be scarcely perceptible. If the interposed plateis broader than the coils, the reduction in the shockis still greater. The magnetizing power of the cur-rent is also lessened, in respect to hard steel; thus,a sewing needle, placed within a helix, will be butfeebly charged. A certain thickness of metal is re-quired to produce these effects, as several sheets oftin foil may be interposed without diminishing theshocks in any appreciable degree. 410. The interposition of a metallic plate does notprevent the occurrence of the secondary currents, butcauses a great reduction in their intensity. Thatthe quantity of the current is not affected, may beshown by connecting the ends of the upper coil,especially if it be a ribbon co
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Keywords: ., bookcentury1800, bookdecade1850, booksubjectmagnetism, bookyear18
