BETWEEN SUN-SPOT FREQUENCY AND TERRESTRIAL MAGNETISM. 



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smoothed sun-spot frequencies (Ausgeglichene Relativzahlen), each of which is a mean 

 from observed values for 13 months, of which the individual month forms the central 

 period. Table X. gives the mean seasonal and yearly values thus found ; these 

 answer precisely to the seasonal and yearly values based on observed sun-spot 

 frequencies which appear in Table V. 



TABLE X. (Units 1' for D, ly for H and V.) 



Pawlowsk "Quiet" Days with WOLFER'S Smoothed Values (Ausgeglichene 



Relativzahlen). 



So far as the mean yearly and winter values of a, b and b/a, are concerned, 

 Tables V. and X. are in practical agreement, but the equinoctial values of i> in 

 Table X. are decidedly lower, and the summer values decidedly higher, than the 

 corresponding quantities in Table V. The fact that the equinoctial values of b/'n for 

 D and H in Table X. fall slightly below the summer ones seems hardly likely <i priori 

 to be a natural phenomenon, and it is not in accordance with the results obtained for 

 Greenwich, in Tables II. and III., from the longer periods, where the variation of the 

 mean sun-spot frequency from month to month is naturally less than in 1890 to 1900. 



19. The effect of the substitution of the smoothed sun-spot frequencies on the 

 values of b and b/a from month to month is most easily followed by expressing the 

 monthly values as percentages of their mean for the 12 months. Table XL gives the 

 mean of the results thus obtained for D and H, employing smoothed and observed 

 sun-spot frequencies for the "quiet" days, and observed frequencies for the "all" 

 days. The employment of smoothed frequencies for the "all" days would alter the 

 results to about the same extent as it does in the " quiet " days. 



The substitution of the smoothed for the observed sun-spot frequencies for "quiet" 

 days removes an isolated prominence shown by the b variation in March, and removes 

 slight depressions in June and August, but it produces a depression in September and 

 adds materially to an already conspicuous prominence in May. Also the June 

 depression and the March prominence are not apparent in the " all" day b variation 

 using the observed sun-spots, and if we used smoothed frequencies for the " all " days 

 we should have a marked depression in March and a largish prominence in June. 



