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he intimates a general disagreement with the paper, confining his criticism to 
the analogies ; to these only, therefore, can I apply myself. I would remark, 
by the way, that the conclusion drawn from analogy not being an essential 
portion of my argument, but purely supplemental, it might be withdrawn 
without prejudice to my plan. However, let us come to the criticism. The 
first demurrer is as to the threefold character of the law of attraction. Mr. 
Warington says this is an extremely disputed point, and his conclusion is 
that it must be given up. Now, if rightly disputed and proved to be an 
error, of course it must give way. But is Mr. Warington willing to at once 
concede everything in science that is disputed ? I suspect not. At any rate, 
I am not, and till his allegation is not only mooted, but proved, the suggested 
analogy may stand. The next instance is the triple motion of the heavenly 
bodies, and Mr. Warington truly says, again, the last of the three is “ dis- 
puted and, if so, again we reduce the three to two. I rejoin, Not quite “if 
so if so, and proved to be an error, and if proved not to move through space, 
proved also not to oscillate in space, well and good, and the analogy 
must be withdrawn ; but till then — till disproved, not disputed only — 
this too may stand. The next analogy is light ; and of the three alleged 
spectra, Mr. Warington says they are convertible the one into the other, 
being only modifications of the same force. But separate modifications of 
the same thing are not identities. The presence of new accidental differences 
or external qualities effectually forbids us to regard such modifications as 
identical. I await therefore the proof, not the bare assertion, that there are 
not really three spectra. But the mention of the luminous spectrum being 
compounded of three rays awakens not only Mr. Warington’s surprise, but 
his sarcasm. “ Such a fallacy, he should have thought, would by this time 
have vanished from every scientific mind.” I submit to the correction, if 
correction it really be, not however quite assured that even yet we have 
reached the final truth. Within no very lengthened period of years the 
doctrine as to the luminous spectrum has passed through more than one 
phase. Once supposed to present seven colours, the number was subse- 
quently limited to three. Now we are told the number exceeds all limit — • 
“ an infinite number.” Are we to rest at this point ? On the analogy of 
atmospheric air, the criticism is both as to fact and expression. Atmospheric 
air, Mr. Warington tells us, is not a compound, but a mixture. Is this 
distinction technical, or is it solid ? If solid, I at least err in good company. 
J ohnson says that a compound is “ a mass formed by the union of many 
ingredients” : a mixture is “a mass formed by mingled ingredients.” I 
fully recognize the verbal or numerical difference, but I fail to perceive the 
exact bearing of the criticism in this place. As to the fact, the history of 
atmospheric air would seem to square with that of the luminous spectrum — 
it is variable. Originally I believe supposed to consist of only the two gases 
which so largely preponderate, it was afterwards considered to consist of 
three. Mr. Warington now tells us that the number is unlimited. Again, 
I ask is this our resting-place ? I would also venture to ask whether this is 
really the normal state of atmospheric air, or is it not its local and accidental 
