[JACKSON] MAGNETIC HORIZONTAL FORCE AT AGINCOURT 



23 



much larger in Ci and C4 and smaller in C2 and C3. The seasonal variations 

 of the phase angles at Agincourt are in each wave larger in summer 

 than winter and the same is true of the Kew values but the range is 

 slightly larger at A in the 24 hour, 12 hour and 6 hour waves and smaller 

 in the 8 hour wave than at Kew. The 24 hour term has its maximum 

 at A occur on the average for the year 42 minutes earlier than at 

 Kew, the 12 hour term at about the same time, the 8 hour term 56 

 minutes later at Agincourt than at Kew and the 6 hour term 43 minutes 

 later at Agincourt than at Kew. 



Grouping the years 1905 and 1906, and the years 1902 and 1912 

 whose mean sunspot frequencies, as given by Wolfer,^ are 58-6 and 

 4-3 we get the diurnal inequality ranges as given in Table IV. The 

 ranges for all years 1902 to 1912 inclusive are also given. 



Table IV. 

 H Diurnal Inequality Ranges at Agincourt. 



.'Ml years 



Max. Sun Spot years. . . 

 Min. Sun Spot years. . . , 



Y/10 



225 

 244 

 179 



Percentage Values. 



All years.— 



Max. Sun Spot years. . . 

 Min. Sun Spot years. . . . 



69 

 76 

 62 



The ranges are expressed also in the percentages of their arith- 

 metic mean values, from which the effect during sunspot maximum 

 and minimum is better disclosed. From the ranges it is seen that the 

 values in maximum sunspot years are throughout the year larger 

 than in minimum sunspot years and that the excess is more pronounced 

 in winter than in summer. 



From the percentage values the effect produced in maximum- 

 sunspot years is seen to be the bringing together of the winter and sum- 

 mer values. 



The results of analyzing the seasonal diurnal inequalities for these 

 different groups of years is given in Table V. 



^Bulletin Mount Weather Observatory, Volume V, Part 6. 



