oe 
wis 
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 /ast 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 amoment, 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 
