THE PRINCIPLES OF MYODYNAMICS. 1 55 



i8i, theii will the indicator of the dynamometer 

 W point to i8 nearly. So that the other rect- 

 angular component will be 3 pounds. And P 

 will have a moving component of 18 pounds, 

 acting in the direction f e. Theoretically 18' -[~ 



3^ = i8i. But ih = 333,6; and 18' + 3^ 

 = 333. Experiment substantiates theory by 

 agreeing with it very nearly. 



1 39. (a.) The second thing to do experi^nentally 

 is to apply the principle of the lever to the resolu- 

 tion of the force of the dynamometer, representing 

 the contracting 7nuscle, iido its rectangular com- 

 ponents : The principle is that the force in the 

 continuity of the lever equals the sum of the 

 forces acting at the ends of the lever. 



(b.) Let S b (Fig. 29) be the short-bar of 

 the myometer ; let L B be the long-bar ; let P 

 be the dynamometer representing the muscle ; 

 let F be the dynamometer representing the 

 pressure that one bone makes on the other ; 

 and let W be the weight. L B represents the 

 fixed bone, and S b represents the movable 

 bone : Then S b is a lever of the first order. 



