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THE RESONANT RECORDER
10, 20, or 200 vibrations per second. The writer is suspended at the centre of a circular electromagnet, the current in which is periodically interrupted by the reed C (fig. 116). When the writer and the reed are exactly tuned then the vibration of the reed throws the writer into a sympathetic vibration.
Fig. 116. Upper part of Resonant Recorder. (From a photograph.)
Thread from clock, not shown, passes over pulley P, letting down recording-plate; S, screw for vertical adjustment; T, tangent-screw for exact adjustment of plane of movement of recorder parallel to writing-surface; V, axis of writer supported perpendicularly at centre of circular end of magnet; C, the vibrating reed; G, smoked glass plate.
Determination of the Latent Period.
The reliability and accuracy of this method of automatic record of extremely short intervals of time is
