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somewhat discursive remarks which have been made upon my paper. But 
I must claim, in fairness, to offer some explanations, because of the unusual 
form the discussion has assumed. Mr. Brooke has occupied nearly the time 
of a second paper in opposition to my remarks. My paper was prepared 
before I knew that Mr. Brooke had read one on a kindred subject, and 
mainly in reference to Mr. Herbert Spencer’s First Principles and Dr. Tyn- 
dall’s recent address. In fact, it continued a line of thought in a paper read 
at the Brighton Congress. When the Honorary Secretary sent me Mr. Brooke’s 
paper, I could not avoid making some remarks upon it, since I differed from 
it so widely. My criticisms upon it were quite supplementary, and almost un- 
avoidable, and I am sorry this part of the subject should have this evening 
had an unnecessary prominence. I stated very clearly that Mr. Brooke’s 
views were in entire contrast with those of Mr. Spencer and Dr. Tyndall on 
the moral aspect of the question. But we are here to maintain truth 
honestly, without respect of persons, and cannot safely disguise our convic- 
tion that certain views are wholly false, even though they are shared by some 
friends who are on our side in the main controversy. My chief object was 
to show that Mr. Spencer and Dr. Tyndall are not only wrong in their ap- 
plication of their theory of force or energy to moral questions, but in their 
conception of the principle itself, and that their view, when closely examined, 
is stored and steeped with logical contradictions. Now since Mr. Brooke 
adopts their doctrine, in words, as a grand recent discovery of science, and 
then discards Newton’s definition of force, and frames a new one of energy 
in order to remove the difficulties which it involves at every turn, it was 
essential for me briefly to point out what I conceive to be such fundamental 
errors, and so fatal to the possibility of a clear conception of my argument. 
One first and main question between us is whether we are bound to use the 
fundamental terms of science in their usual sense, accepted by the standard 
authorities, or may vary them at our own pleasure, and adopt wholly differ- 
ent ones in their stead ? The definition of force which I used is that of 
Newton and all his successors. Mr. Brooke himself quotes half a dozen 
leading authors who agree in it, but only to charge them with having gone 
wrong together. He distinguishes force from the action of force, and makes 
the contrast of force and energy to be, that the first is potential, and 111 > 
second actual. But the force of Newton’s Principia and all dynamical 
works of authority is actual force, measured by its preseut actual effect in 
change of motion. And the only energy which is force in any sense is called 
“ potential energy,” as its very definition, in Dr. Thomson and Tait’s treatise, 
and similar works, where the conservation of energy receives scientific treat- 
ment. So that Mr. Brooke exactly inverts the relation between them by 
the usual and accepted definitions. The result of such an arbitrary change 
and reversal must be interminable confusion of speech and thought. His 
force is the mere possibility of force to be exercised hereafter, and his action 
of force, or energy, is the force, in Newton’s sense and that of all dynamical 
treatises, which exists and acts at any particular moment. Now if we in- 
clude all the possibilities of force, past, present, and future, under the name of 
