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exertion of force ; but an “ act ” of volition I should consider to be, giving 
effect to will by action on matter, in conformity with that inscrutable relation 
between spirit and matter, whereby we have the power to move material 
substance, and can thus give overt evidence of our volition. Supposing 
this power to be exerted by the intervention of the ether under certain 
conditions of nerve and muscle, just as, in a well-known experiment, the 
limb of a dead frog is moved by a galvanic current of ether, it must still be 
regarded as a faculty immediately bestowed by our Creator, enabling us, 
when we please, to originate and bring into action the same physical con- 
ditions as those under which the motion in that experiment is produced. 
I can assent to Mr. Brooke’s statement, that when a limb is moved, “ the 
contraction of the muscular fibres is the immediate agent in the exertion of 
the force ” ; but at the same time, as was correctly affirmed by my son, 
Mr. Challis, in the course of the discussion, the views I advocate “go beyond 
the muscles.” In sec. 21 of my paper on “ The Metaphysics of Scripture ” 
I have enunciated the following principle : “ It is inconceivable that there 
can be any production or event which is not determined by antecedent will, 
and by the power, in operation, of a conscious agent.” The adoption of this 
principle precludes the admission that the exertion of muscular force can be 
correctly called a “ material act,” or that in any case there can be exertion 
of force which is not a spiritual act followed by its material manifestation. 
Volition is the necessary antecedent of every manifestation of force, and 
consequently, as volition is an attribute of spirit, every exertion of power 
is a spiritual act. 
Mr. Brooke’s next argument, which is directed against the assumption of 
the spherical form of the atom, is very nearly the same as that which I have 
met in the last paragraph but one of the Supplementary Reply attached to 
my paper on the “Metaphysics of Scripture” (Journal, Vol. XI. p. 245), 
where I make a distinction, apparently overlooked in that argument, between 
a molecule and an atom. The polarity of the crystallographical forces being 
referable, according to my view, solely to the arrangement of the atoms 
which constitute a molecule, I have no occasion to make hypotheses re- 
specting the form of the atoms in order to account for it. Mr. Brooke now 
adds to the former argument the assertion, that if “ the Newtonian hypo- 
phesis,” according to which the spaces between the particles (? atoms) are 
very large compared to the spaces occupied by the particles themselves, be 
adopted, “ it does not matter what we suppose the form to be.” Although 
this might be granted so far as regards the phenomena of polarity above 
mentioned, it might still be maintained that there are other phenomena 
which essentially depend on the form of the atom. The spherical form is 
one of the primary hypotheses of the mode of philosophy I advocate ; and, 
as stated at the end of sec. 22, I have, in fact, accounted for various physical 
phenomena by mathematical reasoning founded on the supposition of this 
form, and have thus established a reasonable presumption of the reality of 
spherical atoms. 
With respect to Mr. Brooke’s objection to the Newtonian expression, vis 
