200 KANSAS UNIVERSITY SCIENCE BULLETIN. 



studies, though she found the end plates in the muscles fa- 

 tigued first. In her experiments fatigue of the right hand 

 decreased the power of the left, which would seem to be a 

 slight contradiction of Lombard's results. 



Since these early ergographic studies the possibilities of 

 the application of the ergographic curve as a means of testing 

 mental fatigue has been assumed by many investigators of 

 the problem in the public schools with very contradictory re- 

 sults. Kemsies (20) found, for example, that (1) Monday 

 and Tuesday are the best days of the week; (2) the first two 

 hours of the day are the best of the day, except on Monday; 

 and (3) vacations of not more than three weeks show a bene- 

 ficial influence in proportion to their length. It was believed 

 that the mental work of the schoolroom produced the decrease 

 in the ergographic tracings, and that there was not complete 

 recovery from one day to the next. 



Bolton (3) tested the method more thoroughly in connec- 

 tion with other tests after both physical and mental fatigue. 

 His results for five tests each showed that the performances 

 with the ergograph were considerably increased after two- 

 hour periods of adding, decreased after two-hour walks, and 

 remained unchanged after two-hour rest periods. However, 

 he was not satisfied that the ergograph was a reliable test. 

 Keller (19), on the other hand, used the same method to test 

 the fatigue induced by rapid reading, and found slight indi- 

 cations of fatigue. Ellis and Shipe (11) repeated Keller's ex- 

 periment, with the result that, while reading showed fatigue, 

 it was not evidenced by the ergographic curves. 



The dynamometer has been used frequently as a more con- 

 venient method of determining muscular ability after mental 

 work, but the results are even more variable than those ob- 

 tained by the ergographic method. This may be due largely 

 to the purely accidental factors that may enter into so brief a 

 test. The physical and mental adjustments at the moment 

 are liable to greater variation than would be possible in a 

 longer test. It is also possible that the subject is able to con- 

 centrate his effort for the moment required, and obscure the 

 fatigue effects. Direct correlation between mental fatigue 

 and the dynamometric readings was shown by Binet and 

 Henri (4), and their results were confirmed by Claviere (8). 

 The latter divided school children into three groups. To the 



