288 Proceedings of the British Association. 



magnetic lines of equal declination, dip, and intensity, were found to 

 differ greatly from those laid down in Gauss's Theoretical Map, the 

 northern and southern hemispheres possessing much greater resem- 

 blance to each other than was indicated by that primary and neces- 

 sarily imperfect essay of the theory. 



The range of Sir James Ross's observations extends over more than 

 three-fourths of the navigable parts of the southern seas ; and you 

 will learn with pleasure that one of his most efficient officers, Lieut. 

 Moore, has been despatched from the Cape, with a vessel under his 

 command, to complete the remainder. 



Nothing could exhibit in a more striking light the completeness 

 of the organization and discipline of the system of magnetic 

 observations, than the observations of the great magnetic storm 

 on the 25th of September 1841 ; it was an event for which no 

 preparation could be made, and which no existing theory could pre- 

 dict ; yet so vigilant and unremitting was the watch which was kept, 

 that we find it observed through nearly its whole extent, and its lead- 

 ing circumstances recorded, at Greenwich, and in many of the observa- 

 tories on the continent of Europe, at Toronto, St. Helena, the Cape, 

 Hobarton, and at Trevandrum in Travancore ; for even the mediatized 

 princes of the East have established observatories, as not an unbecoming 

 appendage to the splendour of their courts. Some of the observations 

 of this remarkable phenomenon, and of many others (twenty- seven in 

 number) of a similar nature, have been discussed, with great care 

 and detail, by Colonel Sabine, and lead to very remarkable conclu- 

 sions. They are not absolutely simultaneous at distant stations, 

 nor do they present even the same succession of phases, as at first 

 anticipated ; and it is the disturbances of the higher order only 

 which can be considered as universal. They are modified by season 

 as well as by place, the influence of winter, in one hemisphere, and 

 of summer in the other, on the same storm, being clearly distin- 

 guishable from each other. The simultaneous movements in Europe 

 and America have been observed to take place sometimes in opposite, 

 and sometimes in the same directions, as if the disturbing cause was 

 in one case situated between these continents, and in the other not ; 

 and we may reasonably expect, when our observatories are furnished 

 with magnetometers of sufficient sensibility to indicate instantane- 



