Caliber

in gunnery, signifies the same as the bore or opening: and the diameter of the bore is called the diameter of its caliber. This expre ion regards all pieces of artillery. | Caliber - Compa es, | | - | | Calliper - Compa es, | the name of a particular instrument used by gunners, for measuring the diameters of shot, shells, . as also the cylinder of cannon, mortars, and howitzers. They resemble other compa es, 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 pa ing through the other, marked with inches and parts, to expre 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, . 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 nece ary for proof and service of bra 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. Log arithmetic 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.