Validity of Ergo graph as Measurer of Work Capacity i x 



way. The effect of practice is to increase the power or capacity 

 for successive discharges so that practice for nerve centers serves 

 to emphasize the tendency to automatic functioning. 



To sum up, in the most automatic centers recuperation is rapid, 

 and in the least automatic it is slow. A period which is sufficient 

 for the recuperation of lower automatic centers will not suffice for 

 the higher centers. The effect of practice upon the higher cen- 

 ters is to render them more automatic, to increase their capacity 

 for recovery, and to make possible explosions which are succes- 

 sive and repeated at short intervals. 



EXPERIMENT 



The particular purpose of this experiment can be definitely 

 stated in the form of a 'question the solution of which has been 

 attempted. Can the ergograph be used as a measurer of work 

 capacity ; and, if so, under what conditions and within what limi- 

 tations will its validity be greatest ? 



Surely the greatest source of error will be found in the lack 

 of acquaintance which the reagent has with the instrument. No 

 apparatus has as yet been found which is so simple that it does 

 not require a certain amount of practice on the part of the rea- 

 gents to be able to use it with good success.' The chief reason 

 for this is that simple pieces of apparatus give such enormous 

 accidental variations that it is practically impossible to obtain 

 results which have any claim to trustworthiness. More complex 

 pieces of apparatus, on the other hand, require considerable prac- 

 tice before they can be used at all. Any piece of apparatus must 

 then be a compromise between the most simple and the very 

 complex. The aim must be for simplicity of construction on the 

 one hand and for constancy and accuracy of measurements on 

 the other. 



The ergograph which was used was a modified form of the 

 pattern designed by Doctor Hoch in Professor Kraepelin's labo- 

 ratory. While it is a great improvement upon the Mosso instru- 

 ment, it scarcely meets all the theoretical objections that have 

 been brought against all ergographs. No instrument has or ever 

 can, probably, measure all the work the reagent does. The best 

 that we hope for is that the record will be a constant proportion 



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