414 M. M. Garver—Sensation and Volition through the Nerves. 
turned, an undulating line was traced spirally round the cylin- 
der; each one of the undulations corresponding to a known 
interval of time. The base of the tuning-fork was connected 
with one wire from the induction coil and the cylinder with 
the other, so that when the primary circuit was broken a spark 
would pass from the end of the style through the paper to the 
cylinder, displacing the lampblack in its passage and leaving a 
small dot in the undulating line or trace. 
The method of using the apparatus was as follows: the wire 
of the secondary circuit connected with the tuning-fork was 
conducted to one side and used to give the signals by placing 
a short break in the wire in contact with the part of the body 
desired, the flesh of the body completing the circuit. The 
resistance in the primary circuit was so regulated that th 
dots,—the fractions of vibrations being estimated in tenths by 
