弯脚圆规

Compasses \Com"pass*es\, n., pl.
An instrument for describing circles, measuring figures,
etc., consisting of two, or (rarely) more, pointed branches,
or legs, usually joined at the top by a rivet on which they
move.

Note: The compasses for drawing circles have adjustable pen
points, pencil points, etc.; those used for measuring
without adjustable points are generally called
dividers. See {Dividers}.

{Bow compasses}. See {Bow-compass}.

{Caliber compasses}, {Caliper compasses}. See {Calipers}.

{Proportional}, {Triangular}, etc., {compasses}. See under
{Proportional}, etc.


Caliber \Cal"i*ber\, Calibre \Cal"ibre\, n. [F. calibre, perh.
fr. L. qualibra of what pound, of what weight; hence, of what
size, applied first to a ball or bullet; cf. also Ar.
q[=a]lib model, mold. Cf. {Calipers}, {Calivere}.]
1. (Gunnery) The diameter of the bore, as a cannon or other
firearm, or of any tube; or the weight or size of the
projectile which a firearm will carry; as, an 8 inch gun,
a 12-pounder, a 44 caliber.

The caliber of empty tubes. --Reid.

A battery composed of three guns of small caliber.
--Prescott.

Note: The caliber of firearms is expressed in various ways.
Cannon are often designated by the weight of a solid
spherical shot that will fit the bore; as, a
12-pounder; pieces of ordnance that project shell or
hollow shot are designated by the diameter of their
bore; as, a 12 inch mortar or a 14 inch shell gun;
small arms are designated by hundredths of an inch
expressed decimally; as, a rifle of .44 inch caliber.

2. The diameter of round or cylindrical body, as of a bullet
or column.

3. Fig.: Capacity or compass of mind. --Burke.

{Caliber compasses}. See {Calipers}.

{Caliber rule}, a gunner's calipers, an instrument having two
scales arranged to determine a ball's weight from its
diameter, and conversely.

{A ship's caliber}, the weight of her armament.

Calipers \Cal"i*pers\, n. pl. [Corrupted from caliber.]
An instrument, usually resembling a pair of dividers or
compasses with curved legs, for measuring the diameter or
thickness of bodies, as of work shaped in a lathe or planer,
timber, masts, shot, etc.; or the bore of firearms, tubes,
etc.; -- called also {caliper compasses}, or {caliber
compasses}.

{Caliper square}, a draughtsman's or mechanic's square,
having a graduated bar and adjustable jaw or jaws.
--Knight.

{Vernier calipers}. See {Vernier}.