PSYCHOLOGICAL PROGRAM AND TECHNIQUE, 



179 



bearings so that it could revolve freely. A light aluminum arm A , fast- 

 ened to the eccentric, extended from the axis of rotation a distance of 

 25 cm. This arm resting against a suitable catch C held the eccentric 

 in a position above its center of gravity and ready to be tipped 

 over to the left by the offset carried by the wheel W. When the 

 eccentric was lifted from the catch C, and pushed slightly past its 

 highest position by 0, which moved from right to left, it then fell of its 



Fig. 44. — Diagram of the automatic pendulum key used to regulate the length of the 

 electric shocks employed as stimuli. 



T, a rigid stud (mounted in the heavy base, B) about which the eccentric, E, bearing the extension 

 arm, A, may revolve; M, a worm-gear motor revolves wheel, W, from right to left, and the 

 offset, 0, carries the arm, A, from its position of rest, causing it to fall to the left; S and S', 

 two switches opened by ^ ; C, catch device for retaining A after its fall; F and F', feet mounted 

 on W and used to close switches, S and S', respectively, preparatory to the next shock; /, 

 insulation material on the arm, ^ ; iS' is mounted on the large disk, D, which is movable by the 

 handle, H. By the scale and pointer, P, mounted on the arc, K, the switches may be set to 

 certain degrees of separation and the disk clamped by lugs, L. The relative size of the in- 

 strument may be gaged by the size of the disk, D, which is 46 cm. in diameter. 



own accord and with a very swift movement, opened the two switches 

 S and *S', and carried through to the catch C. The contacts at >S and 

 S' were so devised that when struck open they remained in this position 

 unless released by pressure from the feet F and F' carried by the wheel 

 W. The contact S was closed by the foot F and was always closed 

 before >S' so as to reestablish the short circuit P, figure 43. The con- 



