American journal of physiology . ent andan automatic short-circuiting key (E), which it was subsequently found necessary tointroduce, the stimuli were controlled in a definite manner. Thus,when A was depressed or in a position of rest, /. c, the position itoccupied when the muscles were completely relaxed, C was raised,through its connection at L, and made to turn on the axis at H, andso to pull on the cord (J) attached to the key E and hence to short-circuit itself automatically. Without this arrangement unavoidablevibrations would have broken the circuit through the sensitive con-tact of a a
American journal of physiology . ent andan automatic short-circuiting key (E), which it was subsequently found necessary tointroduce, the stimuli were controlled in a definite manner. Thus,when A was depressed or in a position of rest, /. c, the position itoccupied when the muscles were completely relaxed, C was raised,through its connection at L, and made to turn on the axis at H, andso to pull on the cord (J) attached to the key E and hence to short-circuit itself automatically. Without this arrangement unavoidablevibrations would have broken the circuit through the sensitive con-tact of a and b and thus have caused the signal marker (B) andthe electro-magnet (G) to act. With this arrangement, however,when A began to ascend, C was lowered and contact made betweena and b, while the spring at E pulled open the short-circuitingkey, the cord J between C and E being relaxed, and so allowedthe current to pass a—b; consequently the ivory-tipped screw c —by elevating C and so drawing b away from a — broke the circuit. Figure Diagram of the double-lever and the recordingapparatus. 338 Allen Cleghorn. as soon as the recording lever (A) of the ergograph (K) began todescend.^ The stimuH used in these experiments were Ught flashed into theeye, a sudden sound, and induction shocks apphed to the skin. Forthe retinal stimulus a flash from a thirty-two candle-power electriclamp was suddenly brought to bear on the eyes, which were in dark-ness, by means of Czermaks lever, the subject at the beginning ofhis muscular contraction breaking the current -^ and so by means ofthe electro-magnet (G) releasing a catch which let fall the shutterof the box containing the electric lamp. The sound stimulus waseffected in the same way, except that the breaking of the circuit re-leased a hammer which struck upon a tin disk connected with theears by a stethoscope. Similar^, in the case of the stimulation ofthe skin, the breaking of the circuit opened the short-circuiting keyin the secondary c
Size: 1590px × 1571px
Photo credit: © The Reading Room / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookautho, bookcentury1800, bookdecade1890, booksubjectphysiology
