[jackson] 



MAGNETIC HORIZONTAL FORCE AT AGINCOURT 21 



The amplitudes and phase angles of the Fourier waves for the 

 different seasons are given in Table III together with those of Kew 

 for the period 1890-1900. 



The Kew^ values, being for a different group of years than that 

 for Agincourt the results are not strictly comparable, but some idea 

 is given of the difference in type of the waves between the two places. 



The sunspot frequency of the Kew group of years is given as 

 41 • T by Wolfer and of the Agincourt group as 2)2> • 7' The Kew values 

 are for certain days called ordinary days and not as in Agincourt for 

 all days. 



Tablt III. 



Amplitudes and Phase Angles of Seasonal Diurnal Inequalities of H at 

 Agincourt (A) and Kew (K). 



The seasonal variations of the amplitudes in A in all terms show 

 the maximum to occur in the summer, but the equinoctial values in Ci 

 and C2 are practically identical with the summer values. A very 

 decided minimum occurs in the winter. Inspection of the Kew 

 values of the amplitudes shows similar seasonal variation in the 24 

 hour, 12 hour and 8 hour terms; but that in the 6 hour term the maxi- 

 mum amplitude occurred in the Equinox. The amount of the seasonal 

 variation in amplitude is also different at Kew, the range at Kew being 



1 Studies in Terrestrial Magnetism, C. Chree, 1912. 



2 United States Monthly Weather Review, April, 1902. 

 ' Bulletin Mount Weather Observatory, Vol. 5. Part 6. 



