THE PRINCIPLES OF MYODYNAMICS. 55 



namic angle is also acute, and move the weight 

 till the dynamic angle is a right angle : — See 

 Fig. 1 5. During this motion the displacing 

 components of the power and weight will co- 

 operate, — ii. As the bony lever moves from the 

 line where the dynamic angle is a right angle to 

 the line where the myodynamic angle is a right- 

 angle, the displacing components of the power 

 and the weight will antagonize. — iii. As the bony 

 lever moves from the line where the myody- 

 namic angle is a right angle, the displacing com- 

 ponents of the power and weight will co-operate, 

 — iv. When the myodynamic triangle is right- 

 angled at the joint, the resisting component of 

 the weight equals the displacing component of 

 the power. — This fact can be demonstrated by 

 the myometer. 



(2.) In a bony lever of the II order : — i. 

 During the motion of the lever from the most 

 acute myodynamic angle to the right-angled 

 dynamic angle, the displacing components of 

 the power and weight will co-operate, — ii. During 

 the motion of the lever from the right-angled 

 dynamic angle to the right-angled myodynamic 



