156 VITALITY AND EFFICIENCY WITH RESTRICTED DIET. 



In actual use the apparatus was not placed as in figure 31, but was 

 moved closer to the table. The subject's left foot was placed at F, and 

 his shin rested in the two notches above. The position of the subject 

 under the stimulus apparatus was so oriented that A, the adjustable 

 connection between the quadriceps muscle and the light-recording lever 

 which rests on the kymograph drum, was directly over the middle of 

 the quadriceps muscle. The hammers, H, fell through 90° from the 

 magnets, M. 



A modification was made 

 on the Blix-Sandstrom 

 kymograph whereby the 

 interval between the two 

 blows from the hammers 

 could be gradually length- 

 ened or shortened at will 

 without causing an inter- 

 ruption in the experiment. 

 The general form of this 

 modification is indicated 

 in figure 27, where M is the 

 kymograph motor and shift 

 gear and D is the drum. 

 A movable gear, G, in the 

 form of a collar, is mounted 

 on the fixed sleeve, V, 

 through which the moving 

 kymograph shaft S ex- 

 tends. To this movable 

 gear a block of insulation 

 material is secured which 

 carries a contact or switch 

 device, C. A small brass 

 worm, W, mounted in the 

 fixed block B, engages with 

 the gear. Thus, by turning the rod R, which extends to a convenient 

 position for the operator, the contact C may be moved in relation to the 

 fixed contact C . Each contact is made of two leaves, one longer than 

 the other, which, by their spring tension, hold themselves together. 

 The insulated arm A is mounted on the revolving shaft and turns 

 with the kymograph drum. The adjustable points in the end of this 

 arm sweep past the contacts and open them in turn, whatever may be 

 their relative positions. As these switches are in series with the 

 electro-magnets (see M, fig. 31) which are supporting the hammers 

 just previous to the stimulation of the patellar reflex, they control the 

 action and the interval between the blows. The wiring diagram 



Fig. 27. — Detail of a device mounted on a Blix-Sand- 

 strom kymograph whereby the interval between 

 the opening of two circuits may be progressively 

 changed. 



M, electric motor; D, drum; S, shaft carrjdng D; V, fixed 

 sleeve; L, leads to two independent circuits; C, a 

 fixed contact mounted on F; B, block in which W, a 

 small worm, is mounted so as to mesh with the gear, G ; 

 G is movable about V and carries contact C. By 

 turning the hand wheel R, which actuates the worm 

 and gear, C may be made to advance or recede from 

 C which is fixed. The insulated arm. A, carried by 

 S and revolving with D, opens C and C" in turn, re- 

 gardless of their relative positions. 



