PROFESSOR TYNDALL ON THE DIAMAGNETIC FORCE, ETC. 
51 
degree be considered conclusive has ever been brought forward, nor do I believe can 
be brought forward, the conclusion seems irresistible, that we have in the agency by 
which bodies are repelled from the poles of a magnet, a force of the same dual 
character as that by which bodies are attracted ; that, in short, “ diamagnetic bodies 
possess a polarity the same in kind but the opposite in direction to that possessed by 
magnetic ones.” 
conceded. While expressing my admiration of the ingenuity of Mr. Thomson’s reasoning, it appears to me 
to labour under the disadvantage of proving too much, his conclusion being equally fatal to polarity of all 
kinds. The argument, I believe, was first publicly urged against myself at the Belfast Meeting of the British 
Association ; but at the Liverpool Meeting last year Professor Thomson himself admitted “ that he had not 
perfect confidence in the truth of the conclusion, as one of the assumptions on which the reasoning was 
founded admitted of doubt.” — See Athenaeum, 1854, p. 1204. Indeed, from many of his published papers, it 
might be inferred that Mr. Thomson actually assumed what I, in the present memoir, have attempted to prove. 
1 refrain from alluding to the negative results obtained by Mr. Farauat in repeating M. Weber’s experi- 
ments ; for though admirably suited to the exhibition of certain effects of ordinary induction, Mr. Faraday 
himself has shown how unsuitable the apparatus employed would be for the investigation of the question of 
diamagnetic polarity. See Experimental Researches (2653, 2654), vol. iii. p. 143. — J. T., May 9, 1855. 
