136 



ABSOLUTE RANGES. 



in eight days out of eleven, so that our information at this season is unfortunately very imperfect. Even 

 during Midwinter the range exceeded 25y on 90 per cent, of the days. 



TABLE L. Horizontal Force Ranges. (Unit ly.) 



Of the 457 days for which the record was complete, except for the trace going beyond the limits of 

 registration, 274, or 60 per cent., had a range over 75y, and 183, or 40 per cent., a range over lOOy. Of the 

 569 days, complete or incomplete, included in the table, 340, or 60 per cent., had a range over 75y, and 

 225, or 40 per cent., a range over lOOy. 



If we compare the D and H results we find that the percentage of days showing a range of over 

 lOOy in H is closely similar to the percentage showing a range of over 2 in D. As 1' in D range 

 answers to about 2y in H, the natural conclusion which one would also draw from the diurnal 

 inequalities is that diurnal variations of force were considerably larger in the direction perpendicular 

 to the magnetic Meridian than in the magnetic Meridian itself. The conclusion is almost certainly 

 correct. At the same time, it should be noticed that even when the H magnetograph was least sensitive 

 it was impossible to record a range much over 200y, while the possible limit for D was equivalent to 

 nearly 600y throughout. Thus any deduction based on Tables XLIX and L as to the relative size of 

 the average daily ranges in D and H is practically certain to underestimate the range in H. 



41. Table LI gives some data for V analogous to those in the last two tables. Days are arranged in 

 six groups, the first including cases where the range did not exceed 50y, the second cases in which it 



TABLE LI. Vertical-Force Ranges. (Unit ly.) 



