[JACKSOX] 



MAGNETIC DECLINATION AT AGINCOURT 



109 



The amplitudes and phase angles are given in Table III for the 

 different seasons and for the year, and along with them are given 

 those for Kew for the period 1890-1900, which, while not strictly 

 comparable, being for a group of years whose sun spot frequency 

 according to Wôlfer is 41 • 7 1 while that for the group of years used at 

 Agincourt is only 33 ■ 7 2 , nevertheless show some very striking resem- 

 blances. The Kew values 3 are for certain days only, called ordinary 

 days, and not as in Agincourt for all days, and this also may accentuate 

 or otherwise the differences between the two places. 



Table III. 



Amptitudes and Phase Angles of Seasonal Diurnal Inequalities at 

 Agincourt (A) and Kew (K). 



Comparing the amplitudes of the A and K values of the different 

 terms the seasonal variations, except in the case of the 8 hour term, 

 are seen to be the same. In the 8 hour term the Agincourt maximum 

 is in the summer, whilst at Kew it is at the Equinox. One striking 

 difference between the two places is the fact that at Agincourt the 

 amplitudes of the 24 hour term and the 12 hour term are much the 

 same, whilst at Kew that of the 24 hour term is from 1 • 5 to 2 • times 

 as large as that for the 12 hour term. The 8 hour and 6 hour terms 

 at both places are about the same. 



Looking at the phase angles the seasonal variations are seen to 

 be almost the same except in the case of the 6 hour term where sea- 

 sonal variation is large at Agincourt and almost nil at Kew. In 



1 U. S. Monthly Weather Review, April, 1902. 



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



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



