21 



Set the drum going, and, when it is revolving uniformly, 

 strike the tuning fork vibrating one hundred times per second 

 so as to set it vibrating and holding it by the handle, and with 

 the two limbs in the vertical plane, bring the wire attached 

 to one limb against the drum under the muscle trace and run 

 off a time trace. Each tooth on the tracing represents 

 Tffir second. 



Make two tracings, one for each Student. 



G. Record the Nature of Experiment. 



With a pin or other sharp-pointed instrument write upon 

 the paper the nature of the experiment and the date. 



H. Fix Trace. 



Remove the paper from the drum, and fix the trace by 

 passing it through photographic varnish. Hang it up to dry. 



I. Read Trace. Work out Results. 

 When dry, study and measure. 



(a) The Duration of 



1st. The time between the application of the stimulation 

 and the contraction. 



2nd. The time taken up by the contraction. 



3rd. The time of relaxation. 

 And record them. 



(6) Extent of Contraction. 



Measure the extent of movement and the length of each 

 limb of the lever, and calculate the actual shortening of the 

 muscle as in A, p. 17. 



Measure the length of the muscle, and calculate the per- 

 centage shortening. 



(c) Weight Lifted. 



Measure the distance of the weight from the fulcrum, and 

 calculate the actual weight lifted by the muscle as in B, p. 17. 



(d) Work Done. 



Calculate the work done by the muscle as in C, p. 17. 

 Preserve the trace and the calculations in your note-book. 



