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condition ? Mr. Warington next asks, respecting water, What is there of 
triple constitution here ? He passes over my qualifying words, “ at least 
in respect of its accidents,” the presence of which accidents, as in the case 
of the solar spectrum, certainly exhibits the three modifications specified, and 
which modifications I contend are not identities. Next, triplicity in elec- 
tricity. Mr. Warington says, “ I have always understood that electricity is 
not of three — but of two forms, positive and negative, vitreous and resinous.” 
Granted. Some have even advanced the theory of two distinct electricities. 
But to look once more a little beyond the one technical use of the word 
“constitution,” Johnson tells us that it is “ a system of laws ” ; and again, 
“ particular law ” ; and I presume the fundamental laws of electricity are 
admitted to be threefold — the attraction of bodies in opposite states of 
electricity, the repulsion of bodies in similar states, and a body in a natural 
state attracting bodies both positively and negatively electrified. On this 
head of triplicity Mr. Warington adds, “We are not told how.” True : I 
merely stated what I believed to be the fact ; and in such reticence, if 
I erred, I erred in good company. When Humboldt speaks of terrestrial 
magnetism, he simply states the truth as to its “ triple elements his ex- 
planation, however, is elsewhere — viz., that its main character is “ expressed 
in the threefold manifestation of its forces ” — something very like character- 
izing it by its laws of operation rather than by its forms. The next instances 
to which Mr. Warington demurs are the threefold vital mechanism and the 
threefold nervous system in the human subject. He says that he utterly 
fails to see these points. All I can reply is, that others of the learned and 
honourable profession of which he is himself so eminent a member do see 
them ; and we are only therefore in the universally acknowledged dilemma, 
“ Who shall decide when doctors disagree ?” Mr. Warington’s closing criticism 
is upon the expressions in relation to space. He tells us that “ before ” is 
a reality, and “behind” is a reality, but “here” is a line ; “and what is a 
line but a thing which has no extension ?” Well, I had always thought that 
“ here,” as in relation to elsewhere — e.g., “ before and behind” — was the space 
which the speaker occupied, and as palpable a reality as either of the other 
terms. Moreover, had I attempted to define the junction or separation of 
the two, I should certainly have not represented it as a “ line.” Taking 
man’s standpoint theoretically , the extension can only be lineal, and the 
junction or separation only a point ; but taken practically , and man’s place 
is a solid, and the junction or separation must be a solid also. I marvel that 
Mr. Warington did not, as in the cases already noticed, suggest the unlimited 
theory put forth by, I think, Professor Sylvester before the Royal Society? 
in the form of there being n dimensions in space. When this theory is 
accepted, and when n dimensions, or even four dimensions, are proved, I 
shall be ready to withdraw the analogy. But Mr. Warington tells us that 
“ a line has no extension.” I had always understood that a line had length ; 
and is not length extension ? Mr. Warington must forgive me if I yield to 
the strong temptation to quote his own sarcasm : — “ I should have thought 
that such a fallacy would by this time have vanished from every scientific 
