Magnetism of the Earth. 399 



Moreover a needle inclosed in a spiral seven feet in diameter may- 

 be magnetized in this way. Hence it is altogether probable that a 

 current passing round the earth, at a great distance, might produce 

 this effect after some time. Hence the sun or moon, or indeed any 

 of the heavenly bodies in our vicinity might produce this effect by 

 their relative motion round the earth, provided the electricity of any 

 of them exceeds that of the earth in intensity. Again, as the magnet- 

 izing effect of the calorimeter, is equal to that of a galvanic battery, 

 we know not but heat may be the chief or only magnetizing agent. 

 In this case, the relative motion of the sun round the earth would 

 produce the effect. Again, is there not a current in the atmosphere 

 from east to west? and as the great mass of the atmosphere is usually 

 positive, this would produce the same effect if electricity is the cause. 

 It might also, if heat is the cause ; for in the latitude of the trade winds, 

 the mean temperature of the air probably exceeds that of the earth. 



The fact, that the magnetizing effect is increased with the number 

 of turns in the spiral, appears to me to be an evidence that it is the 

 transverse or circular, and not the spiral direction which is essential ; 

 and that the only advantage of the spiral direction is to keep the cur- 

 rent for a longer time in the vicinity of the needle. This is further 

 evinced by the fact that magnetism may be produced by a current 

 simply transverse. But if the spiral direction should be considei-ed 

 essential, it would be easy to show that the different bodies of the so- 

 lar system describe spirals, and the different portions of our atmos- 

 phere a series of partial spirals on the earth's surface. And it is a 

 curious fact which has probably never been noticed, that the position 

 of the poles is as it should be if the earth's magnetism were caused 

 by a magnetizing fluid moving in the direction of these spirals. For 

 it would move from right to left, when proceeding from south to north, 

 and from left to right, when proceeding from north to south, which is 

 perfectly analogous to the experiment with the needle and wire above 

 related. Lastly, I would suggest the possibility that electricity situ- 

 ated above the earth's atmosphere may produce magnetism in a sim- 

 ilar way. 



P. S. This communication was sent in 1823, to the Editor of the 

 Boston Journal of Philosophy, with a request that it might either be 

 inserted, or communicated to the American Academy of Arts and Sci- 

 ences. The receipt of it was publicly acknoAvledged by the editor, 

 but whether it was read before the society I am unable to say, not hav- 

 ing^ seen their transactions. 



