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the sun's heat, light, or attraction. What other influence 

 then can the sun exert on the earth ? 



The analogy between the magnetism produced in a spin- 

 ning top by the inductive action of a distant body charged 

 with electricity, and the magnetism in the rotating earth, 

 probably caused by the influence of the sun, which influence 

 is not its mass or heat, seems to me to suggest what the 

 influence which the sun exerts is. If the sun were charged 

 with negative electricity, it seems to me to follow, from what 

 the experiments I have described establish, that its inductive 

 effect on the earth would be to render it magnetic, the 

 poles being as they are. 



The only other way in which the sun could act to produce 

 or influence terrestrial magnetism would be by its own 

 magnetism. If the sun is a magnet, it would magnetise the 

 earth. If this is the cause the sun's poles must be opposite 

 to those of the earth. Now, it follows that such a condition 

 of magnetism would or might, if its materials are magnetic, 

 be caused by the rotation of the sun under the inductive 

 action of the earth and planets in exactly the same way as 

 that caused in the earth by the inductive action of the sun. 

 As the direction of rotation is the same in both bodies, and 

 the electricities of the opposite kind, the magnetism would 

 be of the opposite kind also. So that on this hypothesis it 

 is probable the sun would act by both causes. 



When I first worked out this idea, I was not aware that 

 anything like it had been suggested before ; but Mr. 

 Baxendell, after having seen my experiments, noticed a 

 review of a book on terrestrial magnetism, to which he 

 kindly called my attention. The author, without making 

 any assumption with regard to the electrical condition of 

 the sun, assumes it to act on the earth's magnetism precisely 

 as it would under the conditions I have described ; and he 

 then proceeds to consider, not only the general . features of 

 the earth's mao-netism, but all its details — and this in a 



