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XLIII. Some Experiments connected •with the Relations of 

 Calmic to Magnetism. By John Murray, Esq. F.L.S. 

 M.W.S. Sfc. 



To the Editors of the Philosophical Magazine and Journal, 



T has not been determined whether the deviation of the 

 magnetic needle in M. Oersted's interesting discovery, to 

 the east or west according as it is posited above or below the 

 uniting wire of the VoUaic circle, is to be attributed to the 

 caloric evolved, or the electricity developed. 



The following experiments seem to prove that ihe former is 

 the efficient cause of this declination ; and, as connected with 

 the relations of heat to magnetism, the short and simple detail 

 may be deemed of interest. 



I used a long and slender magnetic needle taken from a 

 theodolite. It was freely suspended by a thread of flos silk 

 attached to its centre, and depended from a brass stand. 



On bringing the flame of a spirit lamp eastwai-d of the south 

 pole, it was primarily slightly repelled by the flame, and on 

 the lamp being withdrawn the south pole moved toisiard the 

 east to the amount cf 45° declination, and then slowly retro- 

 graded to its former position. 



The flame being introduced -westward of the south pole, 

 seemed to attract the needle ; and on being removed, the south 

 pole deviated still more considerably toward the east, and 

 finally slowly I'eturned to its proper station. 



The lamp was next brought "westward of the 7iorth pole, and 

 the flame seemed in the first instance to repell it; when the 

 lamp was withdrawn, the north pole moved toward the west, 

 and the deviation amounted to 70°. After a proper interval 

 it resumed its previous locality. 



The flame, now brought eastward of the north pole, first 

 exhibited an attractive influence; and on its removal the north 

 pole slowly advanced westward, and at last retrograded. 



The amount of the declination will of course vary, and will 

 depend on the proximity and continuance of the flame. 



The flame brought under the centre of the suspended needle, 

 occasioned a circular motion. 



I am, gentlemen, 



Your obedient servant, 

 Gloucester, March 1st, J823. J. Murray. 



XLIV. Re- 



