PSYCHOLOGICAL PROGRAM AND TECHNIQUE. 



153 



turbed by many action currents coming from the body muscles. Sud- 

 denly these action currents cease, indicating that the subject has settled 

 back into the chair; the pulse remains rapid or perhaps becomes more 

 rapid than during the actual intervals of exertion, and then, gradu- 

 ally, the heart cycles lengthen, while the subject is quietly resting 

 in the chair. Only the large R wave of the electrocardiogram com- 

 plex can be seen during the period of exertion. Pulse-cycle length 

 was measured from R to R} 



In order to have an added indication for placing the moment when 

 exertion began and ended, a key was arranged at one end of the bar and 

 was operated by the subject's weight. 

 When this key was closed by the weight 

 of the subject on the bar, a signal mag- 

 net which was in circuit and placed be- 

 fore the slit of the camera was caused 

 to deflect. The shadow of this signal 

 marker was recorded on the photo- 

 graphic paper (see U and D in figure 24.) 

 The switch was arranged as shown in 

 the diagram in figure 25. One of the 

 leads, L, in circuit with the battery 

 and the signal magnet, connected to the 

 metal clamp which was about the bar B; 

 the other lead connected to the brass 

 sleeve S. This sleeve contained a stiff 

 spring, one end of which rested in the 

 bottom of the sleeve and the other against 

 the wooden bar. The spring was around 

 the hook H, which connected the bar to 

 the chain. When the downward pres- 

 sure was placed upon the bar a contact 

 was made at point C. It required 4.5 kg. 

 of weight to close the circuit. Thus the 

 signal was given very early after the 

 subject grasped the bar and the circuit 

 remained closed until the subject had 

 almost relaxed in the chair. To econo- 

 mize time in preliminary adjustments, the bar was kept at the same 

 height for all the subjects during the whole experiment. 



The form of electrodes designed and used is shown in figure 26. A 

 set consisted of three pads, R, L, and G, a 4-foot cable, and a plug, P. 

 Each pad was made of 8 thicknesses of cotton gauze, a piece of German 

 silver, 0.005 inch in thickness and 11 cm. wide by 20 cm. long, with a 

 piece of felt for backing. The edges of the gauze were tucked in around 



1 Miles, Carnegie Inst. Wash. Pub. No. 266, 1918, p. 95. 



Fig. 25. — Detail of the key closed 

 by the subject's weight during 

 physical exertion. 



H, hook connecting to chain support; 

 S, a sleeve for holding a stiff spring 

 in position against the bar, B; L, 

 leads in circuit with battery and 

 signal magnet; C, point of con- 

 tact for circuit closure when weight 

 is supported on B. 



