233 



nature, not one of them being taken from any published do- 

 cument ; that the first document of the kind, which pro- 

 fessed to give any account of M. Neumann's ** method," or 

 any statement of the principles employed in it, appeared in 

 the Annals of Poggendorf, (vol. xl. p. 497,) some months 

 after Mr. Mac Cullagh had published his last paper on the 

 subject in the Philosophical Magazine, (vol. x. p. 43,) and 

 even after that paper had been noticed in the aforesaid 

 Annals, (vol. xl. p. 462) ; that M. Neumann's Memoir in the 

 Berlin Transactions was not published until a later period ; 

 that, therefore, there could be no question about priority of 

 publication ; and that, consequently, if it were to be ima- 

 gined, for a moment, that either author had borrowed from the 

 other, the presumption must necessarily be against M. Neu- 

 mann. With respect to M. Seebeck's note, it would be enough 

 to state, that M. Neumann is not mentioned there at all; 

 that the principles there given by M. Seebeck are not ade- 

 quate to the general solution of the problem ; and that 

 such of them as differ from those of Fresnel, had been 

 previously published by Mr. Mac Cullagh. It was clear, 

 therefore, that Mr. Mac Cullagh owed nothing on the score 

 of theory to any one but Fresnel. He had, indeed, made one 

 alteration in his theory as it originally stood ; for he had 

 at first rejected Fresnel's law of the vis viva, and had been 

 obliged to restore it afterwards, in order to account for cer- 

 tain experiments of M. Seebeck, which M» Seebeck himself, 

 from want of sufficient principles, had not attempted to ac- 

 count for ; but the real service which M. Seebeck had rendered 

 him, and for which he had frequently acknowledged his ob- 

 ligations, was the communication of these experiments, and 

 not any suggestion of the law of vis viva, which he knew 

 well enough before. In all this, however, it was plain that 

 M. Neumann had no concern, unless he chose to say, that 

 he had appropriated to himself Fresnel's law of the vis viva, 

 that he had determined to regard it as the foundation of his 



