Revisions of Field Computations 



29 



Substituting the value of AT 1 from (6) in (7) and (8) and noting that the final computed 

 value of H is the mean of H and of H d (the value resulting from deflections only), we 

 obtain 



AH=-Hr (1.1574 x 1(T 5 ) (9) 



Am= -mr (1.1574 x 10 -5 ) (10) 



These corrections apply when the original computations have been made with a zero rate; 

 if any other rate has been used, r may be taken as the difference between the rate used 

 and the adopted rate. Table 7 gives the values of the corrections from (9) and (10) for 

 values of H from 0.02 to 0.40 C. G. S., for magnetic moment from 100 to 1000, and for 

 daily rates of the chronometer from 1 second to 60 seconds. 



A rapid approximation quite close enough for ordinary purposes, except when the 

 rate is abnormally large, may be made without reference to the table from the formula 



AH=--Hr 

 b 



en: 



AH being in gammas, H in C. G. S. units, and r in seconds, with the usual convention as 

 to sign. 



1 The tabular corrections are on the basis that H and m are computed from oscillations and deflections without cor- 

 recting the observed time of one oscillation for finally adopted rate of chronometer; for values of // and m based <>ii oscil- 

 lations only the tabular corrections must be doubled. 



