Electro-physiology (1896-98) Electro-physiology electrophysiolog01bied Year: 1896-98 368 ELECTRO-PHYSIOLOGY CHAP. metal wheel, but in circuit with one another, are the two points (brushes) forming closure of the galvanometer, which at a certain point of the revolution pass through the mercury pools of two isolated steel cups (gl, g2), or over amalgamated copper contacts included in the galvanometer circuit (J51; B.,\ The pools (contacts) are movable, so that the duration of the simultaneous dip, duration of galvanometer closure (T), can be altered within a wide margin. Now, instead of ex
Electro-physiology (1896-98) Electro-physiology electrophysiolog01bied Year: 1896-98 368 ELECTRO-PHYSIOLOGY CHAP. metal wheel, but in circuit with one another, are the two points (brushes) forming closure of the galvanometer, which at a certain point of the revolution pass through the mercury pools of two isolated steel cups (gl, g2), or over amalgamated copper contacts included in the galvanometer circuit (J51; B.,\ The pools (contacts) are movable, so that the duration of the simultaneous dip, duration of galvanometer closure (T), can be altered within a wide margin. Now, instead of extending this interval over the surface of the curve of variation as above, the distance of the time (T) from the moment of excitation (t, t1'), etc., is regulated in Bernstein's instrument by alteration of the slider FIG. llo.—Bernstein's differential rheotonie (seen from above). which carries the exciting contact. The whole arrange- ment of the experiment resembles the diagram (Fig. 116). Owing to the complicated structure of the gastrociiemius, the sarfcorius is better adapted for the study of the negative variation, its demarcation current being compensated to start with. In consequence the galvanometer magnet remains at rest during rotation, and is only deflected when there is an alteration of the muscle current during the time (T). If the slider is then ;irranged, as in Fig. 116, so that the closure of the circuit of the primary coil occurs at the same moment at which the galvanometer circuit is broken by the two contacts, a complete revolution occurs before the closure of the muscle
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