40 



ANIMAL MECHANICS. 



Mr. Jevons* experiments (holding weights with arm 

 horizontal). 



w. t (observed). 



t (calculated). 



Difference. 



14 lbs. 32.5 sees. 



10 ,, 1 60. 3 „ 

 7 » \ 87.4 „ 

 4» 147.9 » 

 2 „ 218.9 

 1 „ 321.2 „ 



34. 2 sees. 



5*. 7 m 

 84.8 „ 



14' . 6 ,, 



234 4 



305.5 » 



— 1.7 sees. 

 4 5-6 „ 

 + 2.6 „ 

 + o.3 »> 

 -15-5 „ 

 + IS-? » 



The agreement here shown between observation and 

 theory is quite satisfactory, and I remained quite contented 

 with it, until I came to plot the curve (12a), and compare it 

 with the observations, as shown in the accompanying dia- 

 gram (page 41). 



The relation between t and w represents a curve of the 

 fifth degree, one branch of which is shown in the figure ; the 

 other branch being hyperbolic in form, corresponding to 



positive values of t, and negative values of w greater than ^. 



Mr. Jevons' observations are shown by the small circles cor- 

 responding to the weights used by him, and their agreement 

 with the curve is evident. 



Differentiating equation (12a) we find 



dt ^ (6w + a) (3*0 + a) 

 dw (%w + a) 5 



(us) 



The preceding equations prove that — 



i°. The values of t are positive, whether a weight be 

 held in the hand, or whether the hand be supported by a 

 force acting upwards. 



2°. The axis of wis asymptotic to the curve at positive 

 and negative infinity. 



