9U 



It is much to be desired, the author states, that so remarkable a 

 result should receive a full confirmation, by the continuance of the 

 observations at Toronto and Hobarton for such an additional period 

 as may appear necessary for that purpose ; and that the general con- 

 clusion, indicated by the observations at those stations, should be 

 verified by similar investigations in other parts of the globe, especially 

 at the observatories which now exist. He conceives that these facts 

 indicate the existence of a general affection of the whole globe 

 having an annual period, and would appear to conduct us naturally 

 to the position of the earth in its orbit as the first sfep towards an 

 explanation of the periodic change. He further urges the importance 

 of following up without delay, and in the most effective manner, a 

 branch of the research which gives so fair a promise of establishing, 

 upon the basis of competent experiment, a conclusion of so much 

 theoretical moment. 



In conclusion the author adverts briefly to considerations which 

 may give a particular importance to accurate numerical values of the 

 magnetic elements and their secular changes at Toronto, namely the 

 proximity of that station to one of the two points on the northern 

 hemisphere, which are the centres of the isodynamic loops, and are 

 the points of the greatest intensity of the force (on the surface of 

 the globe) of apparently two magnetic systems, distinguished from 

 each other by the very remarkable difference in the rate of secular 

 change to which the phenomena in each system appear to be subject. 



