508 BELL SYSTEM TECHNICAL JOURNAL 



TABLE 1 

 A Ten-Hour Record Obtained by Means of the Beat Recorder. 



The columns 5i, 62 and 83 indicate the difference between each oscillator and the 

 mean of the three during each 1,000 second interval expressed in parts in one hundred 

 million. 

 Serial Mean {f,-fz) (/* - /s) iU - h) 



by a, b, and c respectively, it can be shown readily that the numbers 



a -\- h -\- c , a -\- h -\- c a + 6 + c , a -{- h -\- c ,_. 



O' -A . o ;; , c and (7) 



4 4 4 4 ^ ^ 



represent the difference between each of the oscillators Nos. 1, 2, 3 

 and 4 respectively and the mean of all four, expressed in parts, in 

 one hundred million. This method treats all four oscillators sym- 

 metrically. The symmetry is evident if we substitute in (7) the 

 values (2) assigned to a, b, and c, whence we get: 



