ANNALS 



^ PHILOSOPHY, ' 



Ji7iF, 1825, 



Article I. 



Essai/ on the Variation of the Mariner's Compass ^ its Cause, and 

 ^ the periodical Revolution of the Magnetic Pole, By Mr. 

 *' C. Boner. 



(To the Editors of the Annals of Philosophy/,) 



GENTLEMEN, Great Bedford-street, Bath, 'r 



Th e direction of the magnetic needle towards one particular 

 point in the horizon evinces a power, by which the needle is 

 attracted. 



The progressive change in the direction of the needle proves 

 a change of position in the attractive power. 



The consideration that every thing in nature is governed by 

 invariable laws, places it beyond a doubt that the change of 

 position in the attractive force, and consequently the variation 

 of the needle, are governed by laws as constant as those by 

 which all the other phenomena of nature are regulated. 



Whether the cause of the variation, that is to say, the power 

 which acts upon the compass needle, be in the earth, or m the 

 heavens, is a question which I do not presume to decide ; 

 because, after the consideration that the most able men have 

 been unsuccessful in their efforts to establish their theories upon 

 solid grounds, and that besides circumstances have never per- 

 mitted me to make the necessary experiments, from which I 

 might have drawn just conclusions, 1 should think it ridiculous 

 conceit, if I were positive in affirming that such and no other is 

 the efficient cause of this extraordinary phenomenon. 



However that neither of the existing systems is the true one, 

 is evident from their disagreement with daily experience ; and, 

 therefore, every new conjecture on so important a subject is 

 worth examining. 



That there should be within the earth, as some pretend, a 

 large magnet, revolving about a center, as the planets move 

 ^bout the sun, is possible, but not probable ; and still less so iis 



Neiv Series vol, x, b 



