162 DR. C. CHREE: AN ENQUIRY INTO THE NATURE OF THE RELATIONSHIP 



S 11. Table V. presents several novel features. In the declination we see a 

 conspicuous difference between the variation of a throughout the year on " all " and 

 on "quiet" days. In December and January the "all" day value of a is more than 

 double the "quiet" day value, and the excess of the "all" day value is also 

 prominent in November and February. On the other hand, the " quiet " day value 

 of a is, in general, distinctly the larger throughoxit the equinoctial and summer 

 months. There is no such prominent difference between the "all" and "quiet" day 

 values of b for declination. There are, of course, conspicuous differences in one or two 

 individual months, but the seasonal and yearly values are closely alike. The rise of 

 b/a in winter and its fall in summer are conspicuous, especially in the "quiet" 'days, 

 where the phenomenon is even more prominent than at Kew. The mean values of 

 b/a for the year from "all" and from "quiet" days are in close agreement with one 

 another and with the corresponding Kew value. 



In H the seasonal and yearly values of a in "all" and in "quiet" days are much 

 alike. The winter and equinoctial values of b in the two cases are also nearly equal, 

 but in summer the "quiet" day value is very decidedly the smaller. The mean 

 "all" day value of b for the year is distinctly larger than the " quiet" day value, 

 which is itself slightly in excess of the corresponding Kew value. The excess of b/a 

 in winter is conspicuous in both "all" and "quiet" days; in the latter case the 

 variation of b/a throughout the year is pretty similar to that at Kew. 



In V the "all" and "quiet" day phenomena are vitally different. The fact that 

 the mean diurnal range during the 11 -year period for the "quiet" days was barely 

 40 per cent, of that for "all" days prepares one for a material difference between the 

 phenomena in the two cases, but hardly for the "all" day mean yearly value of b 

 being more than six times the corresponding " quiet" day value. The " quiet" day 

 value of a for summer is not much less than the "all" day value, but in the 

 equinoctial and winter months the latter greatly predominates. The value of b is 

 greatest at the equinox in both " all " and " quiet" days ; in fact, in " all " days the 

 summer value of b falls short of the winter value, notwithstanding a marked 

 depression in December and Jamiary. The variation of b/a throughout the year on 

 " quiet" days is somewhat irregular. In " all " days we have the fall in summer and 

 rise in winter seen at Kew, but there is a prominent depression in December and 

 January. As regards the absolute magnitudes of b and b/a, the " quiet " day data 

 are much closer than the " all " day to the Kew results. 



Table V. gives only " all" day data for I, as no " quiet" day data for this element 

 seem to be published. 



Here again the phenomena resemble those observed at Kew, b being conspicuously 

 small in winter and b/a small in summer. The values of a and b are, on the whole, 

 distinctly larger than at Kew (where the diurnal range of I is less than at Pawlowsk), 

 but the mean value of b/a for the year is 105 X 10 ~ 4 as compared with 111 X 10~* 

 at Kew. 



