CALIBER-_Compasses_, CALLIPER-_Compasses_, the name of a particular instrument used by gunners, for measuring the diameters of shot, shells, &c. as also the cylinder of cannon, mortars, and howitzers. They resemble other compasses, except in their legs, which are arched, in order that the points may touch the extremities of the arch. To find the true diameter of a circle, they have a quadrant fastened to one leg, and passing through the other, marked with inches and parts, to express the diameter required: the length of each ruler or plate is usually between the limits of 6 inches and a foot. On these rulers are a variety of scales, tables, proportions, &c. such as are esteemed useful to be known by gunners. The following articles are on the completest gunners-callipers, viz. 1. The measure of convex diameters in inches. 2. Of concave ditto. 3. The weight of iron shot from given diameters. 4. The weight of iron shot from given gun bores. 5. The degrees of a semicircle. 6. The proportion of troy and avoirdupois weight. 7. The proportion of English and French feet and pounds. 8. Factors used in circular and spherical figures. 9. Tables of the specific gravity and weights of bodies. 10. Tables of the quantity of powder necessary for proof and service of brass and iron guns. 11. Rules for computing the number of shot or shells, in a finished pile. 12. Rule concerning the fall of heavy bodies. 13. Rules for raising of water. 14. Rules for firing artillery and mortars. 15. A line of inches. 16. Logarithmetic scales of numbers, sines, versed sines and tangents. 17. A sectoral line of equal parts, or the line of lines. 18. A sectoral line of plans, and superficies. 19. A sectoral line of solids. CALIBRE, _Fr._ See CALIBER. CALIBRE, _Fr._ signifies, in a figurative sense, cast or character; as _un homme de ce calibre_, a man of this cast. CALIBRER, _Fr._ to take the measurement of the calibre of a gun. A particular instrument has been invented for this purpose. It resembles a compass with curved branches, which serve to grasp and measure a ball. CALIVER, an old term for an arquebuse or musket. CALOTE, _Fr._ a species of scull cap which officers and soldiers wear under their hats in the French cavalry, and which are proof against a sabre or sword. Calotes are usually made of iron, wick, or dressed leather, and every officer chuses the sort he likes best. Those delivered out to the troops are made of iron. CALQUING, CALKING, the art of tracing any kind of a military drawing, &c. upon some plate, paper, &c. It is performed by covering the backside of the drawing with a black or red colour, and fixing the side so covered upon a piece of paper, waxed plate, &c. This done, every line in the drawing is to be traced over with a point, by which means all the outlines of the drawing will be transferred to the paper or plate, &c.