Current from the main : the medical employment of electric currents / by W.S. Hedley.

  • Hedley, W. S. (William Snowdon)
Date:
1896
Catalogue details

Licence: Public Domain Mark

Credit: Current from the main : the medical employment of electric currents / by W.S. Hedley. Source: Wellcome Collection.

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    ing drawings and descriptive particulars of a simple and efficient apparatus adapted to meet the varied demands of direct electrical treatment.* It is based upon the principle of the variable shunt already recommended and described by me,t but it presents some novel features : (1) The resistance is not altered step by step, but gradually throughout its whole range; (2) the switch and resistance are so interlocked that it is impossible to open or close the main circuit until the potential across the shunt circuit is nil; (3) it has a very wide range; and (4) it has an adjustable stop so that any range from zero to the limit may be obtained. It will at once be seen that this apparatus forms a convenient means of obtaining continuous current for the purpose named. In common with batteries it has the advantage that the pressure across the patient's circuit is only that absolutely necessary for the pur- pose in hand, whilst it is without many of the dis- advantages inseparable from batteries—their uncer- tainty, polarisation, cost, and the ever-recurring trouble of recharging. Its use is not recommended upon transformed systems without the intervention of a good transformer. Figs. 1 and 2 are the plan and elevation respec- tively; Fig. 3 is the end elevation showing the interlocking arrangement; and Fig. 4 is a diagram- * This apparatus will also actuate the coil. The requirements for light cautery and the charging of accumulators are simple and adequately met by existing apparatus in the catalogues of the instrument makers. t The Lancet, May 4th, 1895.
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