466 



ANIMAL MECHANICS. 



On comparing these experiments with those made by 

 Mt. Jevons and myself, the small value of the weight of the 

 arm appears striking. Converting kilograms into pounds, 

 we find — 



Mr. Jevons' arm =10 9 lbs. 



Dr. Haughton's arm = 8.5 „ 



" . , ( right arm = 4.41 

 Mr. Nipher's . ° ~ * " 



( lett arm - 4.85 „ 



In Mr. Nipher's experiments, however, there may have 

 been some peculiarity in his mode of raising the weight, 

 which prevented the full Weight of the arm from coming into 

 play. We have already seen that, in Mr. Jevons' experi- 

 ments made in raising weights by means of a pulley, the 

 weight of the arm disappeared altogether from the result, 

 which is expressed by the equation (124). 



The useful effect obtained by Mr. Nipher's experiments is 

 found from (133), by calculating the product of w and n. 

 This gives the formula, 



Useful effect = wn - — ■ . (iia) 



a Y 



V 



This represents a cuspidal cubic, as before, having a 

 maximum ordinate corresponding to the weight, 



I find, by using the numerical constants already given, the 

 following comparison between theory and observation : — 



