FORCE, ENERGY AND WILL.

ONE benefit due to the advance of physical science is, as Professor Clarke Maxwell has remarked, the introduction into common speech of words and phrases consistent with true ideas about nature instead of others implying false ideas. But though our scientific progress has produced this amongst so many other beneficent effects, yet, as its advancing stream has left here and there a stagnant pool, so we may not unreasonably expect every now and then to meet even with a temporary verbal backwater. Thus electrical discovery by the term “electric fuid' has left in the popular mind the illusion that electricity is a fluid substance which flows from one body to another. But a really grave misconception in some respects a retrograde error) appears to me to be coming daily more diffused with regard to the conceptions energy and force.'

The term “force' has, of course, definite and exact meanings! (not always quite consistent however) assigned to it in physics ; but it is the more general, not the exact use of the term to which reference is here made. • Force' becomes known to us partly through the sense of effort and resistance overcome which attends our muscular activity, and partly through the exercise of will, as perceived in exerting our voluntary mental activity-force of mind being a term of familiar use as well as force of arm. We have, therefore, force in our own being as the active exercise of mental and bodily powers which are possessed by our complex organisms. The sensations of effort and resistance we experience are the occasions through and by which our intellect comes to perceive that surrounding bodies

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| Thus Professor Tait, in his Lectures on Some Recent Advances in Physical Science, defines (at page 16) .force'as 'any cause which alters or tends to alter a body's natural state of rest or of uniform motion in a straight line.' At page 364 he says : 'Force is the rate of change of momentum,' and adds that the term.is obviously to be applied to any pull, push, pressure, tension, attraction or repulsion, &c., whether applied by a stick or a string, a chain or a girder, or by means of an invisible medium such as that whose existence is made certain by the phenomena, of light and radiant heat.' At page 358 he adds : 'Force is the rate at which an agent does work per unit of length.' In Nature, July 5, 1877, he tells us : ‘In all probability there is no such thing as force.' Force is often taken to denote 'the unknown cause of energy,' energy being the power possessed by a body of overcoming a resistance." Force is also defined as 'mass animated by velocity, or directed pressure.'

have powers corresponding to our own. We do not, however, as some pretend, attribute to surrounding bodies activities such as our own, but only activities having a certain analogy with ours. If we try to pull a man up from the ground against his will and fail from his being more muscular than we are, and if we try to pull up a stone from the ground and fail from its being too heavy to lift, we do not attribute muscular activity to the stone, or to the earth which by gravity retains it; but we perceive a certain relation of analogy between the pulling activity of the man and the pulling activity of the earth, and this though our own sensations constitute the one material by means of which our intellect has the power of apprehending those two very different perceptions. As it is with gravity, so with the other influences (luminous, calorific, electrical, &c.) which surrounding bodies bring to bear on us; we naturally recognise them as the actively exercised powers and properties of such bodies. The sleeper who wakes to find that the earth's rotation has carried him from beneath a tree's friendly shade into the direct influence of a scorching sun, believes that the heat he experiences is due to the activity of that great body acting upon his own organisation, and also believes that activity to be something radically and essentially different both from the activity which blinds him when he attempts to gaze at the sun itself, and from the motion which has exposed him to its rays. Is he right in so believing? If he is, then much of our modern scientific teaching tends to make popular, phrases which imply false ideas about nature, and thus to occasion such an intellectual backwater as has been referred to. The false physical conception also carries with it consequences of far greater moment.

The scientific teaching which I believe implies false ideas about nature is that which concerns the conservation of energy,'? or, as it was earlier named, the persistence and transformation of force.' Few conceptions have of late obtained a wider currency amongst that part of the public which is interested both in physical science and philosophical speculation, than have three represented by the expressions the unity, the persistence, and the transformation of force.'

As to the idea of the metamorphosis of force,' Meyer, Joule, Grove, and Helmholtz are perhaps, as Mr. Herbert Spencer says, more than any others to be credited with’its clear enunciation ;' but certainly its wide diffusion has been largely aided by one who adds to his many claims on our esteem, as a man of science, the gift of a most persuasive eloquence. Indeed, Professor Tyndall's clear expositions of scientific facts, supplemented by the charm of his brilliant rhetoric, have familiarised so many minds amongst us with the conception of the transformation of force, that now a reverent

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acceptance of this belief seems to have become, in the opinion of many, the articulus stantis vel cadentis scientiæ.

But the conception of a persistent “force' which undergoes Protean transformations has found large acceptance in philosophy no less than in science. The many who take Mr. Herbert Spencer as their speculative guide follow him in seeking to express all existences of which we have or can have any knowledge in terms of force'its persistence and metamorphosis—as their only possible ultimate explanation. Mr. Spencer himself has a chapter 3 on the transformation of 'force,' wherein he speaks of the transformation of heat into electricity,' and of this latter, again, into other modes of force; he refers to Mr. Grove as having shown that each force is transformable, directly or indirectly, into the others, and he himself brings even intellect and will within the sphere of such transformations. Indeed he not only teaches that force is a substance, but that it is the substance of substances. He makes the persistence of force as "an unconditioned reality's the most fundamental of all truths. · Deeper,' he tells us, than demonstration, deeper even than definite cognition, deep as the very nature of mind, is the postulate at which we have arrived. ... The sole truth which transcends experience by underlying it is the persistence of force. Here, then, we have a fundamentally different conception of force' from that which was formerly universal-the conception in fact of an actual multiform substance instead of the conception of a property attached to substance, i.e. the activity of a substance.

This change of conception has been brought about by the brilliant discoveries of the quantitative equivalence which exists between the different successive activities of the same or of different bodies, e.g. that quantitative equivalence between heat and motion which has led Professor Tyndall to speak of heat as a mode of motion. The works of the authors before referred to are replete with wonderful examples of this quantitative equivalence between many of the activities which bodies exhibit.

We shall naturally at first be disposed to think that a conception based upon such discoveries, and which has been propagated energetically by thinkers so distinguished, must be a valid one, and that the new phraseology must therefore be a real improvement. Now I should be the last to underrate either the value of the physical discoveries of equivalence between activities or the merit of the illustrious discoverers. Deference is most justly due to the expressed opinions of such men, and we may well hesitate before venturing to regard as mistakes what they appear to deem so important and so true. We have, however, but to consult the history of a few years back to find sufficient evidence that the most distinguished

leaders of thought may fall into the most elaborate speculative errors. Hegel and Schelling, in their day, were men at least as eminent and as esteemed as any of our living philosophers. Yet who now believes that any profound truth lies hid in the judgment that being and notbeing are identical,' enunciated by the former, or considers that the biological speculations of the latter have any real scientific value ? On the other hand, there are not a few who feel no trifling grudge against these writers for having led them through the fame of their writings to expend so much time in acquiring a knowledge of systems which when acquired proved so empty and so worthless. I should be very sorry to be thought wanting in respect for the labours and fruitful speculations of the veteran Professor Schwann, who will ever deserve the gratitude no less than the admiration of biologists; but, fully recognising his merits, we may yet ask, who now accepts his cell theory as put forward by him ?

Fortified with such reflections, we need not shrink from respectfully questioning the conclusions of the most distinguished physicists or the most widely accepted philosophers of to-day, even if it were not the rule both in science and philosophy to be ever demanding demonstration, and never resting on authority. We may then without scruple express not only our scepticism, but our positive disbelief in the new creed - I believe in One Force' —and we need not shrink from entering our protest against the danger of superstition contained in this credo. The protest seems to me needed, for I fail to see why a belief in a supposed, but really non-existent, agent invisibly entering into, and as invisibly quitting the visible objects around us, should be deemed other than superstitious.

But what, then, is this awful reality of which all known or knowable existences are but modes ? This force, this now so widely reverenced entity, the Alpha and Omega of the Spencerian school, this Being of Beings, which seems the great Pan not only alive once more, but actually seizing on the vacant throne of Zeus, is, in my judgment, a mere figment of the intellect. For "force'is but an abstraction, a common term denoting the diverse activities of all known and unknown existing substances, and it has therefore no existence, as force, other than as an idea in some mind. The attempt, then, to explain all phenomena by the persistence and transformation of force is an attempt to explain everything by an abstraction.

The new way of speaking has, not unnaturally, come into fashion as a consequence of the recognition of that quantitative equivalence between successive activities which has been of late years so happily discovered, and which can be most conveniently expressed by it. But though it is thus convenient to express such changes (especially experimental changes accurately measured) in terms of a persistent

force, yet all the physical phenomena capable of expression in such terms seem to me to be also capable of expression in terms of the hypothesis that bodies of different kinds really exist objectively, and have really and objectively active powers also of different kinds. The conception of the same or different bodies being successively affected, and acting successively in different manners, with a quantitative equivalence between the modes of their affection and activity, seems a sufficient conception to apply to the mechanism and action of a moving locomotive steam-engine, &c.—one as consonant with facts as is the conception of a force which is transformed from heat into motion.

On the other hand, to speak of force persisting and being transformed favours the conception of force as some objectively existing thing which really passes out of one body into another, and has a positive substantial existence. Thus it is sometimes said that a coal-bed contains the heat and light of the sun of bygone ages shut up within it, like enchanted knights, and once more to be set free upon that coal's combustion. But does it really contain them? Surely neither that light nor that heat is in the coal, nor are they in the oxygen with which that coal may one day combine ; they are activities resulting from the rapid combustion of those bodies.

It may perhaps be replied that there has in fact been no intention of really inculcating the substantial existence of force, and that the language used has been employed simply as a convenient way of speaking. Now I most willingly concede the reasonableness of making use of the conception of such an entity as “force' as a working hypothesis, provided care be taken that its real nature be not misunderstood ; but if by that term not a real existence, but an ideal abstraction be, in fact, what is meant, then it would surely be better not to speak of its persistence, and à fortiori of its transformation,' since nothing can be transformed' which does not really exist.

It will perhaps be replied that if we ought not to speak without qualification of force, we ought not so to speak even of particular forces—heat, light, and electricity, &c.—which, as such, are also abstractions; that we ought, in fact, to avoid the common phrases employed in every-day life. To this it may be rejoined, in the first place, that the active powers of bodies do really exist, and that therefore it is most reasonable to apply to similar powers a common name; while for the real, though not the substantial, existence of calorific, luminous, and electric activities we have the plainest evidence. Nor need we even object to the term .force' as a common name for all active powers whatever, provided its substantial existence, beside the existence of the various active bodies, be not asserted or implied. But secondly, I reply that though it is well to employ the common terms heat, light, electricity, &c. (meaning by such terms the objective