An international system of electro-therapeutics : for students, general practitioners, and specialists . plished by a stationary primarycoil, over which are glided at will helices composed of wire of varyingthickness and length. The continuous-coil apparatus, as ordinarily con-structed, comprised in a single compact helix all the merits of the sepa-rate-coil apparatus with its various and cumbersome helices, with thesingle exception of an inability in the beginning to yield a sufficientlyslight current, especially when the so-called quantity currents were usedinternally by the bipolar method.
An international system of electro-therapeutics : for students, general practitioners, and specialists . plished by a stationary primarycoil, over which are glided at will helices composed of wire of varyingthickness and length. The continuous-coil apparatus, as ordinarily con-structed, comprised in a single compact helix all the merits of the sepa-rate-coil apparatus with its various and cumbersome helices, with thesingle exception of an inability in the beginning to yield a sufficientlyslight current, especially when the so-called quantity currents were usedinternally by the bipolar method. In the device (Fig. 78) suggested byDr. A. D. Rockwell, and made by the Kidder Manufacturing Company,this difficulty has been successfully overcome by having a permanently-fixed helix, A, with a movable primary coil, B. Tlie total length of the coil of this helix is 7552 feet, with the fol-lowing subdivisions : 696 feet of No. 21 wire, tapped at 116 and 580 feet;2116 feet of No. 32 wire, tapped at 783 and 1385 feet; 4740 feet of wire, tapped at 1740 and 3000 feet. The heavy coil of No. 16 wire. Fig. 78.—The Rockwell Coil foe Currents of Quantity and Tension. has been discarded and the No. 21 coil so arranged as to 3ield a currentequal to No. 16. The merit of this arrangement consists of ones abilityto use the whole 7000 feet and more of wire, or to utilize, at will, eachsection of the coil with its subdivisions far more readil} than whenthey are wound on separate spools, and at the same time to increasethe current-strength b}^ imperceptible gradations from zero to themaximum. So high is the resistance offered b}^ the great length of wirein such a helix as this that a comparatively large electro-motive force isnecessary to run it. Almost any form of cell can be used. If any one of the sal ammoniac cells be used, it is a good idea tocombine them in multiple arcs of two each. In this way polarizationtakes place much less rapidly than when they are connected in simpleseries
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectuterus, bookyear1894
