l5o THE PRINCIPLES OF MYODYNAMICS. 



In the long bar are fastened, on opposite 

 sides : Two screw-eyes eighteen inches from 

 the center of the mortices ; two screw-eyes nine 

 inches from the center of the mortices ; two 

 screw-eyes three inches from the center of the 

 mortices. (4.) In the short bar are fastened, 

 on opposite sides : Two screw-eyes eighteen 

 inches from the pivotal pin ; two screw-eyes 

 nine inches from the pivotal pin ; and two 

 screw-eyes three inches from the pivotal pin on 

 either side. (5.) A screw-eye is fastened into 

 the thin part of the long-bar directly in a line 

 with the long axis of the two transverse mort- 

 ices. (6.) The long-bar will represent a fixed 

 bone, and the short-bar will represent a mova- 

 ble bone : The short bar can be used as a lever 

 of any order. 



137. (i.) Select three spring-scales, which 

 have equal resistances under equal tensions. 

 To determine this point, hook the spring-scales 

 together and make tension ; if the scales have 

 the same resistance, the indicators will always 

 point to figures of equal value. The importance 

 of this comparison is obvious. 



