PRACTICAL EXERCISES 



707 



ensure that when the writing-point of the myograph lever has been 

 once adjusted to the drum, successive stimuli will cause contractions, 





the curves of which all rise from the same point. Close the key in 

 the primary, set the drum off (fast speed), open the short-circuiting 

 key, and as. soon as the muscle has contracted once, close it again. 



