TABLE VI. 



TABLE VII. 



Probable error of one difference, M^ 5 = 3-9 X 10 7 sec. 



M,,-7 =3-0 

 21-M, =2-4 



Mean 



3- IX 10 7 sec. 



This value is only slightly less than the mean of e s , e 7 and e 21 , showing that the 

 observations were comparatively free from errors introduced by irregular clock rate. 



18 



