DOCKERAY : PHYSICAL FATIGUE AND MENTAL EFFICIENCY. 207 



of the tube. The upper end of this rod was threaded so that 

 a handle could be adjusted at any height desired. A pointer 

 projected through a slit in the side of the tube and indicated 

 in hundred pounds the tension on the spring. A thread ran 

 from the lower end of the rod through the base, under two 

 pulleys and up through the edge of the base. This thread 

 could be attached to the marker that recorded the results on 

 the kymograph. This furnished a somewhat different sort of 

 exercise from the weights used in the earlier experiments. 

 In place of the long sweeping motion in swinging the arms 

 from the knees to above the head, an exertion of two hundred 

 pounds caused a movement of the handles of the ergograph 

 of about five-eighths of an inch. 



Co. and De. were tested at the same hour, one with the 

 thumb ergograph and the other with the body ergograph. 

 The next day their places were reversed, and on the third day 

 both rested between tests. Do. worked with the wall machine, 

 the ten-minute work periods being begun first and the twenty- 

 minute periods undertaken as the subject felt capable of the 

 longer period. Consequently the twenty-minute periods do 

 not represent exactly twice the fatigue produced by the ten- 

 minute periods, though they alternated with the later ten- 

 minute periods. As Do. worked alone, it was necessary to 

 arrange some sort of a signal to announce the end of the test 

 period. It was found that a stop-watch directly beside the 

 problems on the table was satisfactory. A glance at the watch 

 would indicate the time. While this interfered somewhat 

 with the last problem or two, it was believed the interference 

 was slight. However, it is well to keep this difference in 

 method in mind when considering his results. It was not 

 thought wise to attempt the subdivisions into five-minute 

 periods. The physical work of Ba. was similar to that with 

 the addition tests, supplemented by cross-country running, 

 which was over hills and rough roads and was considered by 

 the subject more fatiguing than a longer distance on the in- 

 door track. The results are shown in Tables Ila and II&. 



SOUNDER TEST. 



A simple attention test was planned for the third series. 

 Pillsbury (32) has suggested the attention wave as obtained 

 with the minimal light as a measure of fatigue, and Mac- 

 Dougall (26) has proposed the marking of dots as they appear 



