This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1818 edition. Excerpt: ...way allow. And therefore the case is not brought to a penetration of dimensions and vacuity, except in the utmost limits of condensation and rarefaction; whereas, these motions stop far short of those limits, as being no more than appetites which bodies have of continuing themselves in their own consistencies or dimensions, and not suddenly departing from them, unless altered by gentle means and by consent. But it is much more necessary, as being a thing of great consequence, to observe that violent motion, as it is called, is no other than this very motion of liberty, tending from compression to relaxation. For, in all simple protrusion, or flight through the air, there is no tendency to motion or change of place before the parts of See the Author's History of Condensation oud Rarefaction/ the body suffer preternaturally, and are compressed by the impelling force; whence it is that some parts successively pressing against the rest, the whole body is driven off, or protruded; and not only in a progressive, but at the same time in a rotatory or revolating motion, so as that by this means also the parts may free themselves, or suffer more equally. Let the fourth motion be the motioa of extension; which is, in some measure, the opposite to the motion of liberty; for, in the motion of liberty, bodies avoid, dread, and fly from a new dimension, or a new degree of dilatation or contraction, and endeavour, with all their force, to recover their former state; whereas, on the contrary, in the motion of extension, bodies affect a new dimension, and sometimes willingly and hastily aspire to it, even with a violent endeavour, as we see in gunpowder. And the most powerful, or at least the most common, though not the only instruments of this motion, ...