ANIMAL MECHAKiCS, 



471 



4 sin-- 



K (.38) 



Substituting this value of Km eq lations (136), we obtain 



(139) 



Statical work = — (w + a) xnt ; 



Kate of statical work = — (w + a) x. 



7T 



The two 'kinds of Work, Dynamical and Statical, just 

 described, are performed by the mnscles of the shoulder, 

 until fatigue occurs. The Law of Fatigue applied to this case 

 gives us the following result :— 



Let 



W = Total work of both kinds : 

 R = Rate of work of both kinds ; 

 W x = Total dynamical work ; 

 R x = Rate of dynamical work ; 

 W 2 = Total statical work ; 

 R 2 = Rate of statical work. 



The Law of Fatigue gives the following equation : 



WR = W 1 R, + W 2 R 2 = constant. (140) 



Substituting, in this equation, the dynamical and statical 

 work and rate of work given in equations (135) and (139), 

 we obtain 



, s , II- /2wVJ /x 



(w + a)~ x- \- +( — 1 t\ n = constant. (141) t 



In the present experiments (w 4- a) x is a constant, and 

 therefore (141) may be thus written, 



