The correlation and conservation of forces

This historic book may have numerous typos, missing text or index. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. 1885. Not illustrated. Excerpt: ... II.--MOTION. OTION--which has been taken as the main exponent IV 1 of force in the above examples--is the most obvious, the most distinctly conceived of all the affections of matter. Visible motion, or relative change of position in space, is a phenomenon so obvious to simple apprehension, that to attempt to define it would be to render it more obscure; but with motion, as with all physical appearances, there are certain vanishing gradations or undefined limits, at which the obvious mode of action fades away; to detect the continuing existence of the phenomena we are obliged to have recourse to other than ordinary methods of investigation, and we frequently apply other and different names to the effects so recognised. Thus sound is motion; and although in the earlier periods of philosophy the identity of sound and motion was not traced out, and they were considered distinct affections of matter--indeed, at the close of the last century a theory was advanced that sound was transmitted by the vibrations of an ether--we now so readily resolve sound into motion, that to those who are familiar with acoustics, the phenomena of Round immediately present to the mind the idea of motion, i. e, motion of ordinary matter. Again, with regard to light: no doubt now exists that light moves or is accompanied by motion. Here the phenomena of motion are not made evident by the ordinary sensuous perception, as for instance the motion of a visibly moving projectile would be, btt by an inverse deduction from known relations of motion to time and space: as all observation teaches us that bodies in moving from one point in space to another occupy time, we conclude that, wherever a continuing phenomenon is rendered evident in two different points of space at different times, there is m...