Water-LEVEL, that which shews the horizontal line by means of a surface of water or other liquor, founded on this principle, that water always places itself level. See the article FLUID.
The most simple is made of a long wooden trough, or canal, whose sides are parallel to the base, so that being equally filled with water, its surface shews the line of level. This is the chorobates of the ancients. See CHOROBATA.
It is also made with two cups fitted to the two ends of a pipe, three or four feet long, about an inch in diameter, by means whereof the water communicates from the one to the other cup; and this pipe being moveable on its stand by means of a ball and socket, when the two cups become equally full of water, their two surfaces mark the line of level.
This instrument, instead of cups, may also be made with two short cylinders of glass three or four inches long, fastened to each extreme of the pipe with wax or mastic. Into the pipe is poured some common or coloured water, which shews itself through the cylinders, by means whereof the line of level is determined; the height of the water, with respect to the center of the earth, being always the same in both cylinders: this level, though very simple, is yet very commodious for levelling small distances.