454 ANIMAL MECHANICS. 



Dr. Haughtoris Experiments (holding Arms horizontal). 



Weight. 



Time. 



Useful 

 Effect. 



o lbs. 



420 sees. 



O 



I „ 



275 „ 



275 



2 „ 



200 „ 



400 



3 » 



147 „ 



441 



4-5 » 



J.OI „ 



454-5 



7 » 



62 „ 



434 



ii „ 



33 „ 



363 



H n 



23 „ 



322 



The useful effect is estimated by taking the product of the 

 weight and the time during which it is held in the horizontal 

 position. 



Using the notation employed in p. 25 ; let 



w = weight held in hand. 

 a = weight of arm. 



t = time of holding arm horizontal, until fatigue sets in. 

 x = distance of centre of gravity of loaded or unloaded 



arm from centre of glenoid cavity. 

 W = the unknown angular velocity. 



The moment of the weights equilibrated by the action ot 

 the muscles is 



moment = (w + a) x. 



The total work done will be proportional to this moment 

 multiplied by the time. 

 Hence 



Total work done = w (w + a) xt, 

 Rate of work = to (w + a) x. 



Hence, by the Law of Fatigue, 



to 2 (w + a) % xH = const. 0 27) 



