92 Sir Norman Lockyer and Dr. W. J. S. Lockyer. [June 3, 



is nearly (a little less than) a quarter of a phase in advance of that 

 indicating the declination change, so that the maximum or minimum 

 point of the latter curve is only slightly in advance of the mean points 

 respectively of the former curve. 



If, therefore, these solar polar regions are capable of disturbing 

 the ' magnetic and electric conditions on the earth, as has been 

 above suggested, then, when they .are most directed to her at the 

 equinoxes, the greatest effects during a year should be recorded, and 

 when they are least directed the effects should be at a minimum. 



It will not be necessary here to refer at any great length to statistics 

 relating to the annual inequality of magnetic disturbances and aurorae, 

 for these have been very efficiently worked out and the results 

 published by Mr. William Ellis.* 



Mr. Ellis has shown that the curves of frequency of magnetic 

 disturbances at Greenwich and Paris are very similar, "showing 

 maxima at or near the equinoxes, and minima at or near the solstices." 

 These also, he further points out, are similar, with regard to the epochs 

 of maxima, to the curve representing the frequency of the aurora at 

 London. In the case of aurorae observed in Edinburgh, North-East 

 Scotland and in different regions in Scandinavia, the months in which 

 the greatest frequency is recorded are September and October (perhaps 

 more generally October) and March and April (perhaps more generally 

 March). Mr. Ellis is inclined to the opinion that there is a small 

 tendency for the autumn maximum to become a little later (from 

 September to October) and the spring maximum somewhat earlier 

 (from April to March) as higher latitudes are approached. 



Further, he points out that in more northern latitudes the mid- 

 winter minimum of lower latitudes appears to diminish and eventually 

 disappears, so that the curve of frequency of the aurora between 

 October and March is practically flat with a small intermediate 

 maximum about January. This change in form of the frequency curve 

 in regions in close proximity to the magnetic pole, and where the con- 

 ditions of day and night are so different, is of great interest, but 

 requires careful consideration before it can be regarded as representing 

 real auroral changes. 



The accompanying curves, fig. 2, illustrate the relation throughout a 



year between the positions of the earth's poles with reference to the 



sun; the positions of the sun's poles as regards the earth; the 



requency of magnetic storms at Greenwich and Paris; and lastly, the 



requency of the aurora as observed at Edinburgh and at stations in 



Scandinavia below latitude 65 N. The first two curves are those that 



re already been given in fig. ], but plotted differently. They have 

 been so arranged that the maxima points represent the epochs 

 h of the poles is most inclined to the sun or earth as the case 

 Monthly Notices, R.A.S.,' vol. 60, p. 112 , vol. 61, p. 537 ; vol. 64, p. 229. 



