Level

(lev'l.) [A. S. læfel.] (Phys.) An instrument for ascertaining when a line is at right angles to the direction of the gravitating force at any given place, and when consequently it lies in the plane of the horizon of that place. A spirit level is attached to the telescope of the levelling instrument by which engineers ascertain the difference of elevation between two points. Levelling may also be performed by the theodolite. The art of Levelling is particularly applied to the laying out grounds, regulating descents, conducting waters, .; and, in fortification, to the reducing an uneven surface to that of a plane, so that the works may be of a corresponding height and figure. [s. 540]