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Duchenne's large volta-faradic apparatus is unquestionably the most perfect for medical purposes. Stöhrer's apparatus is the best adapted for the ordinary exigencies of active practice.
Meyer and Meltzer's combined Voltaic and Faradic Battery. *A, B. Handles to lift out the elements en masse. D. Graduator. E. Levers for raising the cells. F. Interrupting hammer. G. Galvanometer. P. Commutator of the poles. S, S. Terminations of the primary and secondary coils.
Meyer and Meltzer's Combined Voltaic and Faradic Battery.—Messrs. Meyer and Meltzer, of Great
Portland Street, have recently constructed an instrument (fig. 27), containing twenty zinco-carbon cells, and in addition a primary and secondary induction coil. Tested for a week at the National Hospital for the Paralysed and Epileptic, it gave very fair results, and may be recommended both for purposes of diagnosis and treatment to medical practitioners who only occasionally make use of electricity. For anything like continuous work, it is however better to use the separate instruments already described. The prices of this ingenious apparatus are 121. 12s. and 101. 10s.
The Accessories of the Apparatus.
The first necessary accessory is a conducting cord or wire between the poles of the instrument and the sponge holders, electrodes, or as they are generally called rheophores (current carriers). I have had endless trouble with conducting cords, which are always liable to get out of order and cause interruptions in the current. I strongly advise that nothing should be used but very thin copper wire coated with gutta percha in the same way as that known as “telegraph wire.” This is perfectly insulated, sufficiently pliable for all practical purposes; it is inexpensive, it does not kink, it will fit any sort of rheophore, and if the end breaks, all that is necessary is to scrape off with a pocket knife the coating for about a couple of inches from the broken
end. For use when the rheophores remain immovable during the whole time of the application, the ordinary telegraph wire is more convenient, and from its much greater diameter will wear much longer, but it is not sufficiently flexible for other purposes. The other accessories will be described with their special uses in the next chapter.
THE APPLICATION OF ELECTRICITY.
The scientific electro-therapeutic application of electricity is the growth of the last thirty years. Prior to this date the difficulty of obtaining apparatus adapted for the purpose and the consequent inconvenience of the whole proceeding, seems to have stopped all inquirers at the very threshold. To Duchenne (who has been aptly called the “father of electro-therapeutics”) may fairly be ascribed the birth of medical electricity as a branch of therapeutics, and his writings undoubtedly impelled to its study some of the most painstaking physicians, especially in Germany. Before Duchenne no one had attempted any local application of electricity that could be properly so called. The only effort towards this end had been that of Sarlandière in 1825, who conceived the ingenious idea of using acupuncture in order to direct and limit the power of electricity within certain nerves or muscles. The pain of this application, especially when a large number of needles were inserted, and many other disadvantages, precluded it from being adopted in
practice. But it appears to have suggested to Duchenne that in some way it might be possible to arrest electricity in the skin without stimulating the subjacent organs; or on the contrary, to cause it to penetrate the skin without influencing it, and concentrate its power on the deeply-seated muscles or nerves. The result of his experiments was entirely successful, and we owe to him the fundamental principles of all methods of localized electrization. He applied to the dry skin the dry metallic conductors of an induction instrument in action. Sparks and crackling were produced, but no physiological phenomena. The electricity did not penetrate the skin. He replaced the dry conductors by well-moistened sponges. The current produced neither sparks nor crackling, but very variable phenomena of contractility or sensibility, according as it acted upon a muscle, a nerve, or an osseous surface.* Duchenne distinguished between “ direct muscular electrization,” the production of contraction by placing the rheophores on the muscle itself, and “indirect muscular electrization,” in which contraction is produced by exciting the nerve trunk or branches. By the German school these have been also termed “intra-muscular” and “extra-muscular” electrization; but before entering upon this part of the subject, it will be convenient to
* See Duchenne (de Boulogne) “On Localized Electrization and its applications to Pathology and Therapeutics." (English edition.) Part I. pp. 38–44. London : Hardwicke.