202 C.’s Reply to D. (Serr. 
tical argument, tells us is untrue. We all every day see motion 
generated and destroyed. Nor can this objection be answered 
bya supposed difference in the nature of the motion, as we 
cannot'even conceive of any difference in motions, except that 
which is made by their quantity and direction.” 
The reasoning contained in these observations, intended to 
show that the indestructibility of caloric is a strong argument to 
prove it cannot be merely motion, whether well founded or not, 
is too clear to need any further explanation; D. has not 
attempted to answer it, but, as I have shown, he has resorted to 
a method of evading its force, which intelligence and integrity. 
would have alike disdained. 
The next subject of D.’s reply is an objection to the “ gaseous 
body of very great tenuity,” which Mr. H. supposes “ fills all 
space.” The observations are not worthy of notice except as 
affording another instance of the kind of misrepresentation of 
meaning to which D. has resorted. The following is the sen- 
tence to which D.’s observations were applied: ‘The only 
proper answer to such a supposition is, ‘ Show this fluid to me ; 
prove its existence by some other evidence than its being neces- 
sary to support your theory, for that argument can have little 
weight which founds the truth of a theory upon a supposed fluid, 
the existence of which fluid itself rests only upon the truth of 
the theory.’ ” ’ 
To this, D. replies: “ But the oddity of this request is, 
< Show me this fluid.’ Surely C. does not wish Mr. H. to make 
this fluid visible. He does not wish, does he, Mr. H. to catch 
and bring to him a nameless being, a few particles of a fluid, &c.” 
T should think D. would not wish his intelligence should be esti- 
mated so low; as to have it supposed he was incapable’ of per- 
ceiving that I did not mean by the term “ Show,” to express a 
wish to have the fluid rendered visible; but he must choose 
between such an estimation of his intellect and the estimation of 
his fairness, which would arise from the supposition that his 
observations were only applicable to a meaning which he knew 
I did not mtend. 
D. proceeds to observe, “ C.speaks-of Sir Isaac Newton, and 
insinuates to the world that Mr. H.is trying to overturn him. 
Except in the absolute equality of reciprocal attraction in the 
planets, which Newton deduced merely from analogy, and of 
which no proof whatever can be furnished, there is no one phz- 
nomenon in which Mr. Herapath does not perfectly agree with 
Newton.” 
D. would not have much reason to boast of Mr. H.’s modesty, 
if it were true, that he did only differ from Sir Isaac Newton in 
his opinions relating to the mutual attractions of the heavenly 
bodies: on those opinions are established Newton’s noblest: 
; P 
fame; nor-will they, above all others, ever cease to be an honour 
to the age'and nation in which he lived. The evidence of their 
