When we come to an examination of the influences exerted by these powers upon the physical earth, the position, that they must be regarded as the causes of motion rather than the effects of it, will be further considered. At present it is only necessary to state thus generally the views we entertain of the conditions of matter in connection with the imponderable forces and mechanical powers. The conversion, as it has been called, of motion into heat, in the experiments of Count Rumford and Mr. Joule,[12] are only evidences that a certain uniformity exists between the mechanical force applied, and the amount of heat liberated. It does not appear that we have any proof of the conversion of motion into physical power.
It is necessary, to a satisfactory contemplation of the wonderful properties of matter, and of the forces regulating the forms of the entire creation, that we should be content with regarding the elementary bodies which chemistry instructs us form our globe, as tangible, ponderable atoms, having specific and distinguishing properties. That we should, as far as it is possible for finite minds to do so, endeavour to conceive the powers or forces—gravitation, molecular attraction, electricity, heat, light, and the principle which determines all chemical phenomena—as manifestations of agencies which hold a place between the most subtile form of matter and the hidden principles of vitality, which is still vastly inferior to the spiritual state, which reveals itself dimly in psychological phenomena, and arrives at its sublimity in the God of the universe.
FOOTNOTES:
[2] “Motion, therefore, is a change of rectilinear distance between two points. Allowing the accuracy of this definition, it appears that two points are necessary to constitute motion; that in all cases, when we are inquiring whether or no any body or point is in motion, we must recur to some other point which we can compare with it; and that if a single atom existed alone in the universe, it could neither be said to be in motion nor at rest.
“The space which we call quiescent is in general the earth’s surface; yet we well know, from astronomical considerations, that every point of the earth’s surface is perpetually in motion, and that in very various directions: nor are any material objects accessible to our senses which we can consider as absolutely motionless, or even as motionless with regard to each other; since the continual variation of temperature to which all bodies are liable, and the minute agitations arising from the motion of other bodies with which they are connected, will always tend to produce some imperceptible changes in their distances.”—Lectures on Natural Philosophy, &c., by Thomas Young, M.D. Edited by the Rev. P. Kelland. 1845.
[3] “The position which I seek to establish in this essay is, that the various imponderable agencies, or the affections of matter which constitute the main objects of experimental physics, viz., heat, light, electricity, magnetism, chemical affinity, and motion, are all correlative, or have a reciprocal dependence;—that neither, taken abstractedly, can be said to be the essential or proximate cause of the others; but that either may, as a force, produce, or be convertible into, the other:—thus heat may mediately or immediately produce electricity, electricity may produce heat, and so of the rest.... Although strongly inclined to believe that the five other affections of matter, which I have above named, are, and will ultimately be, resolved into modes of motion, it would be going too far at present to assume their identity with it: I, therefore, use the term force, in reference to them, as meaning that active force inseparable from matter, which induces its various changes.”—On the Correlation of Physical Forces, by W. R. Grove, Esq., M.A., F.R.S.
[4] When discussing the hypothesis of Hobbes—that no body can possibly be moved but by a body contiguous and moved—Boyle asks:—
“I demand how there comes to be local motion in the world? For either all the portions of matter that compose the universe have motion belonging to their natures, which the Epicureans affirmed for their atoms, or some parts of matter have this motive power, and some have not, or else none of them have it; but all of them are naturally devoid of motion. If it be granted that motion does naturally belong to all parts of matter, the dispute is at an end, the concession quite overthrowing the hypothesis.
“If Mr. Hobbes should reply that the motion is impressed upon any of the parts of matter by God, he will say that which I most readily grant to be true, but will not serve his turn, if he would speak congruously with his own hypothesis. For I demand whether this Supreme Being that the assertion has recourse to, be a corporeal or an incorporeal substance? If it be the latter, and yet the efficient cause of motion in bodies, then it will not be universally true that whatever body is moved is so by a body contiguous and moved. For, in our supposition, the bodies that God moves, either immediately or by the intervention of any other immaterial being, are not moved by a body contiguous, but by an incorporeal spirit.”—Some Considerations about the Reconcileableness of Reason and Religion: Boyle, vol. iii. p. 520.