ANIMAL MECHANICS. 



171 



Hence the width of the equivalent prismatic muscle may be 

 found : let this width be called W, and we have 



W _ CD = 2Asin0cos0 

 w bb 2^sin0 

 A cos (p 



= T~ ; 



and, finally, 



W= j—t- (29) 



These formulae, applied 

 to the biceps muscle of 

 the Nylghau and Ass, 

 give the following equi- 

 valent prismatic muscles. 



In the Nylghau, the 

 biceps muscle has the 

 following measurements : 

 I = 1.84 m., (p = 50 0 , 

 X = 6 in. 



Hence, 

 L = /see 0 = 2.85 in. 



TJ7 X COS (h 



W = w - 



= 2.09 w. 



In the Ass we have 



1= 1.06 in., 0 = 24°, X- 6.6 in. 



Hence, 



L = I sec (j) = 1 . 1 (f in. 



X COS 0 



W=w ' 



5.688 



It is interesting to observe that the short thick prismatic 

 muscles, to which the penniform biceps of the Nylghau and of 



