EVOLUTION OF QUARTZ CRYSTAL CLOCK 



537 



tenth, would have a frequency of the same order as that of the crystal but 

 differing from it by a relatively low frequency, /i. This low frequency, 

 derived from the modulator was to be used to drive the synchronous motor. 



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Fig. 9 — Early suggestion of means to control a rotating device such as a clock from a 

 high frequency. 



The shaft speed of the motor-generator would, therefore, be integrally 

 related to the crystal frequency and hence any mechanism geared to the 

 shaft, such as a clock, would indicate time as dictated by the crystal. This 

 method could have been carried through readily by a combination of means 

 already developed for other purposes, and the construction of an apparatus 

 based on this suggestion was soon begun. However, a simpler method^^, 



