lO THE PRINCIPLES OF MYODYNAMICS. 



Plane, and the Wheel and Axle, are used. And 

 these principles must be well understood. 



3. There are two principles involved in the 

 Lever : — 



A. (I.) In myostatics — The sum of the 



FORCES ACTING AT THE ENDS OF THE LEVER EQUALS 

 THE FORCE ACTING IN THE CONTINUITY OF THE 



LEVER. That is : — 



I. Order: P+W=F : . . (i.) 



II. Order: P+F^W : . . (2.) 



III. Order: F+W^P : . . (3.) 

 (II.) In myostatics — The Units of power 



MULTIPLIED BY THE UNITS OF DISTANCE IN THE 

 POWER-ARM OF THE LEVER EQUAL THE UNITS OF 

 WEIGHT MULTIPLIED BY THE UNITS OF DISTANCE 

 IN THE WEIGHT- ARM OF THE LEVER. That is: 



P X (P-A)=W X (W-A). 

 In this formula P-A— the power-arm, and 

 W-A= the weight-arm of the lever. 



(w-a) 



Hence, P=:W x : . . . (i.) 



(p-a) 



(p-a) 



AndW=Px : . . . (2.) 



(w-a) 



