THE CHANGE IN FORM 



351 



The Heavy Muscle 

 Lever. 1 It is sometimes 

 necessary to after- load a 

 muscle lever with weights 

 far in excess of those that 

 a light muscle lever will 

 bear without "springing" 

 and thus altering the ab- 

 scissa. Such heavy loads 

 are borne by the heavy 

 muscle lever illustrated in 

 Fig. 60. A tripod of ja- 

 panned malleable iron, 27 

 cm. high and 17.5 cm. 

 broad at the base, supports 

 a femur clamp and a mus- 

 cle lever. The latter is 

 a steel tube 5 cm. long, 

 pierced by a steel axle 9 mm. 

 long, revolving between 

 heavy brass posts. The 

 lever weighs about 2.5 gms. 

 The aluminium scale-pan 

 weighs about 20 gms. ; it 

 holds one hundred 10-gram 

 weights. The lever may be 

 turned completely over in 

 a backward direction, and 



The heavy muscle 



1 American Journal of Physiology, 1903, viii, p. xl. 



