

PRESIDENTIAL ADDRESSES. 523 



those who persevere in the work. We have at 

 present two good and sure connexions between 

 magnetic storms and other phenomena : the aurora 

 above, and the earth currents below, are certainly 

 in full working sympathy with magnetic storms. 

 In this respect the latter part of Mr. Ellis's paper 

 is of special interest, and it is to be hoped that the 

 Greenwich observations of earth currents will be 

 brought thoroughly into relation with the theory of 

 Schuster and Lamb, extended, as indeed Professor 

 Schuster promised to extend it, to include not 

 merely the periodic diurnal variations, but the ir- 

 regular sudden changes of magnetic force taking 

 place within any short time of a magnetic storm. 



In my Presidential Address of last year I referred 

 to the action of the International Geodetic Union, 

 on the motion of Professor Foerster, of Berlin, to 

 send an astronomical expedition to Honolulu for 

 the purpose of making a twelve months' series of 

 observations on latitude corresponding to twelve 

 months' simultaneous observations to be made in 

 European observatories ; and I was enabled, 

 through the kindness of Professor Foerster, to 



