DEPTH, the measure of any thing from the surface downwards.
Measuring of Depth by the Barometer, depends on the same principles on which heights are measured by No 100.
the same instrument. The mensuration of depths being chiefly applied to mines, is still more precarious than the mensuration of heights, on account of the various kinds of vapours with which these subterranean regions are filled. But for a particular account of these difficulties, with the best methods of obviating them, see the articles BAROMETER and MINES.
Depth of a Squadron, or Battalion, is the number of men in a file; which in a squadron is three, and in a battalion generally six. See SQUADRON, FILE, &c.
We say, the battalion was drawn up six deep; the enemy's horse were drawn up five deep.
DEPURATION is the freeing of any fluid from its heterogeneous matter or feculence. It is of three kinds. 1. Decantation; which is performed by letting the liquid to be depurated stand for some time in a pretty deep vessel, till the gross sediment has fallen to the bottom; after which the clear fluid is poured off. 2. Despumation; which is performed by means of the whites of eggs, or other viscid matter, and is also called CLARIFICATION. 3. Filtration. See CHEMISTRY, No 69.