Question of Priority. 143 



taken from any published document ; that the first document 

 of the kind, which professed to give any account of M. Neu- 

 mann'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 prio- 

 rity of publication ; and that, consequently, if it were to be 

 imagined 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 adequate 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 anyone 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 certain experiments of M. Seebeck, 

 which M. Seebeck himself, from want of sufficient principles, 

 had not attempted to account for; but the real service which 

 M. Seebeck had rendered him, and for which he had frequently 

 acknowledged his obligations, 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 foun- 

 dation of his method (le fondement de sa methods), and that 

 thenceforward no one else (however ignorant of such appro- 

 priation) could have any right to use it. 



