THE PRINCIPLES OF MYODYNAMICS. IO3 



Hence, 



P = 300: . . . (2.) 



Therefore, 



W = 45o: . .' (3.) 

 The pressure on the tibio-fibular arch is 45o 

 pounds. 



While F = i5o: . . . (4.) 



(2.) Again, the weight- arm of the lever X 

 the weight = the power-arm of the lever X the 

 power. That is : — 



7i X P = 5 X W : . (5.) 



Also. P 4- i5o = W : . (6.) 



Equating (5) and (6). 



74xP = 5xP + 75o: (7.) 



Hence, P = 300 : . . . (8.) 



And W = 45o : . . (9.) 



The result is the same as before. He7ice the 

 foot is a lever of the second order. 



(3.) It appears, then, that the foot is a lever 

 of the second order, that the ordinary lifting 

 force of the muscles of the tendo-Achillis is 300 

 pounds, and that the habitual pressure on the 

 astragalus, or on the tibio-fibular arch, is from 

 i5o to 45o pounds. Yet the pressure on the 



