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BELL SYSTEM TECHNICAL JOURNAL 



adoption and use of quartz clocks there. Some interesting sidelights on this 

 'Trecision Timekeeping Revolution" were written by F. Hope- Jones in two 

 articles^^" for the Horological Journal during the same year. The quartz 

 clock itself, as developed by the British Post Office for Greenwich Observ-a- 

 tory, was described^^^ in some detail by C. F. Booth in the P.O.E.E. Journal 

 for July 1946. A more general treatment involving some of the same 

 apparatus was presented^-^ by C. F. Booth and F. J. M. Laver in the I. E. E. 

 Journal of the same month. 



Fig. 3d> — Crystal chronometer for geophysical studies, consisting of 100 KC. GT-cut 

 crystal, bridge oscillator, and frequency converters to derive precision 500-Cycle output 

 to operate timing devices. 



An outstanding example of the versatility of the quartz clock has been its 

 application to the measurement of gravity at sea. Knowing of its stable 

 properties and its independence of gravity, Dr. Maurice Ewing in December 

 1935, asked the Bell Telephone Laboratories whether a portable quartz 

 clock could be made available for use during a proposed gravity measuring 

 expedition by submarine in the West Indies. Since this was in line with 

 experimental work already in progress at the time, the first portable ^'crystal 

 chronometer", shown in Fig. ?>3>j was assembled for this occasion, and was 

 taken by Ewing and his colleagues in the U. S. Submarine Barracuda on the 

 trip*"' *' which began at Coco Solo on November 30, 1936, This was the 

 first application of the GT crystal and the bridge stabilized oscillator in 



