Schultz’s chronoscope

uses as a time-keeper a tuning-fork, which, in its vibrations, traces a waved line upon a revolving cylinder. The rupture of each of the targets is recorded by an electric spark deposited on the cylinder near the waved line. The number of waves between the spark spots gives the interval of time when the period of vibration or tarage of the fork is known. The vibration of the fork is sustained by electro-magnets, which alternately attract and release the branches, an interrupter being placed in the circuit. When the current pa ing through the targets is broken an induced current is generated, which deposits the spark on the cylinder in leaping a short break in the circuit. When the first target is broken, by an ingenious contrivance the current is made through the second target before the shot reaches it. The tarage of the fork is obtained by placing a second’s pendulum in the target current, which ruptures the current in each vibration, and produces a series of spark spots on the cylinder. The number of waves between succe ive spots gives the number of vibrations to the second.