THE PRINCIPLES OF MYODYNAMICS. 36 



fulcrum at a. The myodynamic triangle is o i 

 c. And the myodynamic angle is o i c. 



(a) The myodynamic angle is acitte in Fig. 8, 

 right in Fig. 9, and obtuse in Fig. 10. 



(b) From the origin of the contracting muscle 

 draw a perpendicular to the long axis of the 

 movable bone — prolonged if necessary. Com- 

 plete the rectangle o b i d, whose diagonal is the 

 long axis of the contracting muscle. 



(c) As before, when the myodynamic angle is 

 right, there will be one rectangular component. 



(d) Also as before, when the myodynamic 

 angle is acute or obtitse, there will be two rec- 

 tangular components. 



24. A. When the myodynamic angle varies, 

 the magnitudes of the rectangular components 

 will vary. The laws of variation in the magni- 

 tudes of the rectangular components will be the 

 same in a bony lever of the second order as in 

 a lever of the first order : See 22, (i), (2), (3), 



(4). 



24. B. In Figs. 8, 9 and 10, on the long axis 

 of the contracting muscle construct the parallelo- 

 gram o s i c, which shall correspond to and be 



