

BETWEEN SUN-SPOT FREQUENCY AND TERRESTRIAL MAGNETISM. 



163 



12. The data ascribed to the year in Table V. are arithmetic means from the 

 12 monthly values. Table VI. supplies values of a, b and b/a for the ranges from the 

 mean diurnal inequality for the year as given in the Pawlowsk tables. They answer 

 to the range data for Kew in Tables XLIII. and XLIV. of (A), and I give the results 

 in the latter of these tables (calculated by least squares) for comparison. 



TABLE VI. (Units 1' for angles, ly for Force Components.) 

 Mean Diurnal Inequality for the Year at Pawlowsk. 



1.3. The Pawlowsk tables give for each month the mean of the differences between 

 the daily maxima and minima, irrespective of their time of occurrence. The range 

 thus obtained is, of course, larger than that from the mean diurnal inequality for the 

 month, and is a quantity considerably more influenced by magnetic disturbances. 

 The mean of the 12 monthly means may be regarded as the mean for the year of the 

 absolute ranges in individual days. This is the quantity to which the results in the 

 first line of Table VII. apply. The figures in the second line refer to the mean of the 

 12 monthly ranges, a monthly range being defined as the difference between the 

 highest and lowest values recorded during the month. The third line in the table 

 refers to the annual range, i.e., the difference between the highest and lowest values 

 recorded during the year. Owing to occasional losses of trace, monthly and annual 

 ranges are sometimes under-estimated, especially at times of large disturbance. Both 

 quantities are mainly dependent on the amplitude of disturbances ; the mean monthly 

 range is the better measure of the generally disturbed character of the year. 



TABLE VII. Pawlowsk (Units 1' for angles, ly for H and V). 



Y 2 



