ON COMPAKING AND EEDUCINa MAGNETIC OBSERVATIONS. 87 



where h is the solar hour, P is the mean period of a lunation, and t is the 

 age of the moon. 



Designating the variations for the eight different phases by (0), (1), 

 (2) . . . (7), we have 



/•..w= (°)-(^)+w-W - 



And the results for the quarter November 1875 to January 1876 are — 



