SPRING MYOGRAPH. 



171 



(a.) Cover the slip of glass with glazed paper, smoke it, 

 and fix it in the frame. Push the plate to one side by means 

 of the rod attached to it, and fix it by means of the catch. 



Fig. 65. Spring Myograph. 



Close the trigger-key (h), and introduce it into the primary 

 circuit of the induction machine. 



(b.) Make a nerve-muscle preparation, and arrange it to 

 write on the glass plates as directed in 1 (c.) Remember 

 to un-short-circuit the secondary circuit. 



(c.) Press on the thumb-plate (a), thus liberating the 

 spring, when the glass plate moves swiftly to the other side, 

 and in doing so the tooth (d) on its under surface breaks the 

 primary circuit, and the muscle -curve is recorded. 



(d.) Short-circuit the secondary circuit, push back the 

 glass plate, and fix it with the catch ; close the trigger-key, 

 and shoot the glass plate again. This records the abscissa, 

 or horizontal line. 



(e.) Remove the moist chamber, and take the time curve. 

 Push the glass plate back again, and secure it by the catch ; 

 close the trigger-key in order that the conditions may be 

 exactly the same as before strike a tuning-fork, vibrating, 

 say, 1 20 double vibrations per second, and when it is vibrat- 



