in a general sense, implies the motion of a body upwards, or the continual receds of a body from the earth. The Peripatetics attribute the spontaneous ascent of bodies to a principle of levity inherent in them. The moderns deny any such thing as spontaneous levity; and show, that whatever ascends, does it in virtue of some external impulse or extrusion. Thus it is that smoke and other rare bodies ascend in the atmosphere; and oil, light woods, &c., in water; not by any internal principle of levity, but by the superior gravity or tendency downwards of the parts of the medium wherein they are. The ascent of light bodies in heavy mediums is produced after the same manner as the ascent of the lighter scale of a balance. It is not that such scale has an internal principle whereby it immediately tends upwards; but it is impelled upwards by the preponderancy of the other scale; the excess of the weight of the one having the same effect, by augmenting its impetus downwards, as so much real levity in the other; by reason the tendencies mutually oppose each other, and that action and reaction are always equal.

**ASCENT of Bodies on Inclined Planes**, the reader will find explained under MECHANICS; **Ascent of Fluids**, under HYDROSTATICS; and **Ascent of Vapours** under the article EVAPORATION.