THE PRINCIPLES OF MYODYNAMICS. 



41 



axis of the movable bone, prolonged if necessary, 

 and it will represent the moving, or rete7itive com- 

 ponent. 



(b) Drazv a line i^i the long axis of the 7novable 

 bone from the insertion of the contracting miiscle 

 till it meets the line of the moving comp07te7tt at 

 right a7tgles, a7td it zuill represe7it the displacing 



C077tp07ie7lt. 



27. Let i d and o d be the lines representing 

 the rectangular components of the contracting 

 muscle, whose long axis is o i : See Fig. 14. 

 Let a and b be the rectangular components, and 

 m the force of the contracting muscle. 



(a) Then it is evident that we shall have the 

 following proportions : 



a : b : : d i : d o . . . (i) ; 

 a : m : : d i : i o . . . (2) ; 

 b : m : : d o : i o . . . (3) ; 



(b) From these proportions we may derive 

 the following equations :— - 



