or Caliper, properly denotes the diameter of any body; thus we say, two columns of the same caliber, the caliber of the bore of a gun, the caliber of a bullet, &c.

Caliber-Compasses, a sort of compasses made with arched legs to take the diameter of round or swelling bodies. See Compasses.

Caliber-compasses, are chiefly used by gunners, for taking the diameters of the several parts of a piece of ordnance, or of bombs, bullets, &c. Their legs are therefore circular; and move on an arch of brass, whereon is marked the inches and half inches, to show how far the points of the compasses are opened asunder. Some are also made for taking the diameter of the bore of a gun or mortar.

The gunners also sometimes use calipers, to embrace the two heads of any case, in order to find its length.

The calipers used by carpenters and joiners, is a piece of board notched triangular-wise in the middle for the taking of measure.

Caliber-Rule, is an instrument, wherein a right line is so divided, as that the first part being equal to the diameter of an iron or leaden ball of one pound weight, the other parts are to the first, as the diameters of balls of two, three, four, &c. pounds, are to the diameter of a ball of one pound. The caliper is used by engineers, from the weight of the ball given, to determine its diameter or caliper, or vice versa.