150 



TERM-HOUR RANGES. 

 TABLE LXI. Term-Hour Ranges. 



The means at the foot of Table LXI are derived from all the term hours. Omitting the Declination for 

 November 15, and the Horizontal Force for November 15, December 1, January 1, and February 15, so as 

 to have only days for which both Antarctic and Christchurch records were complete, we obtain the 

 following results for the hourly ranges : 



The enormous disparity between the Antarctic and Christchurch results is partly due, of course, to the 

 fact that the range of the regular diurnal inequality is so much larger at the former station. But this only 

 accounts for part of the difference, as may readily be seen by reference to the hourly values on term days 

 given in "Physical Observations," pp. 175-178. The range of the regular diurnal inequality derived from 

 a number of days, even quiet days, is always materially less than the arithmetic mean of the ranges from 

 the individual days, the difference being greater the more disturbed the days. Thus the ratio of the range 

 of the regular diurnal inequality at Winter Quarters to that at Christchurch will be less than the ratio 

 derived when instead of the diurnal inequality ranges one takes the arithmetic mean of the ranges on 

 individual days. 



