86 GENERAL PROPERTIES Otf LIVING TISSUES 



Light Muscle Lever. 1 A stout yoke (Fig. 21) 

 bears two set screws holding a steel axle upon which 

 is mbunted a light piece of tubing and a hard-rubber 

 pulley. One end of the tubing tapers slightly to 

 receive the writing straw. The other projects behind 

 the axle, and may be pressed upon by the accurately 

 cut after-loading screw. The pulley is pierced with a 

 hole for securing a fine wire by means of which a 



Fig. 21. T^ie light muscle lever, with double hook straw fastener ; the 

 actual size. 



weight may be suspended from the pulley when 

 it is desirable that the weight should be applied 

 near the axis of rotation. The muscle may also be 

 weighted directly by means of a scale-pan suspended 

 from the double hook to which the lower end of the 

 muscle is attached. If the tendon of the muscle be 

 fastened to the double hook by a fine wire, the free 

 end of the wire may be carried to the insulated bind- 



1 First Catalogue of Harvard Physiological Apparatus, Sep- 

 tember, 1901. 



