250 



Solar Prominences and Terrestrial Magnetism. [Jan. 14, 



Further, the magnitude of magnetic storms appears to vary accord- 

 ing to the particular position as to latitude of the prominence on the 

 sun's disc. The nearer the poles (either north or south) the prominence 

 occurs, the greater the magnetic storm, and these are the regions where 

 no spots exist. 



In this paper we have shown that the variations of the general 

 magnetic phenomena, as given by Ellis, synchronise with the occurrence 

 of prominences about the solar equator, while his " great " magnetic 

 disturbances occur, in point of time, with the appearance of prominences 

 in the polar regions of the sun. 



Professor Bigelow has recently* investigated the variations in the 

 horizontal magnetic force, and finds that the curve representing these 

 changes exhibits subsidiary maxima which synchronise with those 

 recorded in the curve representing the mean variation of prominences 

 for all latitudes. Thus, to use his own words, " the remarkable 

 synchronism between the curves cannot escape recognition, except 

 .after the year 1894, when an extra minor crest is developed in the 

 horizontal force." 



The accompanying diagram (fig. 2) gives Professor Bigelow's curve, 

 which represents, as he says, " the series of minor variations which 

 were found in the horizontal magnetic force .... after the 11-year 

 cycle curve has been eliminated," together with the percentage 

 frequency of prominences in all latitudes obtained by us from 

 Tacchini's observations. 



* 1 Monthly Weather Review,' vol. 30, No. 7, July, 1902, p. 352. 



