THE CHANGE IN FORM 



359 



Total Work done ; the Work Adder. Attach 

 a scale-pan to the cord that passes over the 

 pulley on the axle of the 

 work adder (Fig. 62). 



The Work Adder. 1 A wheel 

 of aluminium (Fig. 62) bears 

 upon its axle a counterpoised 

 muscle lever ending in a pawl 

 through which the wheel is 

 caused to revolve when the lever 

 is pulled upward hy the attached 

 muscle. A second pawl pre- 

 vents the wheel from turning 

 hack when the muscle relaxes. 

 The axle of the aluminium wheel 

 bears on the other side a pulley, 

 from which the weight is sus- 

 pended. The turning of the 

 wheel winds the suspending cord 

 upon the pulley and thus raises 

 the weight. 



Fig. 62. The work ad- 

 der ; about six-sevenths 

 the original size. The han- 

 dle is not shown. The 

 muscle preparation is the 

 double abductor suggested 

 by Fick. 



Clamp the work adder to 



a stand in si^ch a way that 



the scale-pan hangs free of the table. Fasten the 



tendon of the gastrocnemius muscle preparation 



1 Introduction to Physiology, 1901, p. 225. 

 adder was devised by Fick. 



The first work 



