Electro-physiology and electro-therapeutics : showing the best methods for the medical uses of electricity / By Alfred C. Garratt.
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understand why the sensations produced by the induction cur- rents increase in proportion to the velocity of the interrup- tions, to a certain degree. So much for the immediate sensa- tions. Generally speaking, if the continuous, smooth, or even action of a moderate Galvanic or Faradaic current be directed through a sentient nerve, in a direct or down-running direction, then there is produced a quieting, diminishing, or down4oning effect. If, on the contrary, the current be directed so as to flow through the sentient nerve in an inverse or up-running direction, then there is produced an increased, exalted, or tonvng-up effect; that is, in the former case there is produced diminished sensa- tion ; in the latter case, there is produced increased sensation. This rule is even still more marked, when these currents act upon sentient nerves that are sick and morbidly increased in their sensibility, as in cases of true local neuralgia. But these valuable " general principles" arc still further influenced by the kind of electrodes that are used in the trials, and by the method of managing them and the current. For quieting these nerves, we should always choose broad, soft, warmish and moist elec- trodes, as fine and soft sponges, which are to be gently applied to the skin, within a few inches of each other, and kept in gentle but ceaseless motion, with a careful and gradual letting on of the current, and as gentle and gradual taking it off, after an appli- cation of a minute or less. This may be repeated, after a recess of a few seconds, for some half a dozen times, at the same seance. If not successful, these seances, or sittings, may be repeated every few hours. But for cases of anaesthesia, and wherever we wish to arouse and ivake vp sensation, then not only must the current be inverse in direction, but it may be interrupted, or reversed, or alternated, from second to second, and that through small, say one inch ball, electrodes, covered with wet to ash-leather. The current, here, too, should be strong, and it must be let on, reversed, and interrupted suddenly, but not continued more than a minute at a time. One electrode may be placed over the nerve-trunk, while the other is moving over the palsied periphery, or border points of the palsied muscles. According to the laws of Marianini, as they relate to the pbys-