462 



ANIMAL MECHANICS. 



In order to show the agreement of theory and observation, 

 I have drawn in Fig. (T07) the cubical hyperbola (130), 

 and have represented Mr. Jevons' observations with small 

 circles. 



Fig. 107. — Mr. Jevons Experiments — {Holding Arms hori- 



Third Illustration of Law of Fatigue. — I shall take the 

 third illustration of the Law of Fatigue from the experiments 

 performed by Mr. Nipher.* 



Mr. Nipher lifted a weight (w) through a height (h) in the 

 time (t), sl number of times (n), until the muscles of the arm 

 became fatigued. The arm was raised from the vertical to 

 the horizontal position. The lifts were made isochronous 

 with the alternate beats of a pendulum, and during the other 

 alternate beats, the arm dropped to the side, the weight being 

 caught upon a cushion attached to the leg ; and when the 

 time (t) exceeded one second, the weight was supported upon 

 a framework during the interval of rest. The experiments 

 were made at intervals not less than three hours, and were so 

 arranged as to eliminate from each series, as far as possible, 

 the increase in the power of the muscles produced by the 

 " training." 



The following Table contains the results of one set of ex- 

 periments : — 



w = kilograms, h = 0.74 metre, t = 1.164 sees. 



zontal). 



* Iowa School Laboratory, vol. i„ p. 108 (187 1). 



