Sec"tor (?), n. [L., properly, a cutter,
fr. secare, sectum, to cut: cf. F. secteur. See
Section.] 1. (Geom.) A part of a
circle comprehended between two radii and the included arc.
2. A mathematical instrument, consisting of
two rulers connected at one end by a joint, each arm marked with
several scales, as of equal parts, chords, sines, tangents, etc., one
scale of each kind on each arm, and all on lines radiating from the
common center of motion. The sector is used for plotting, etc., to any
scale.
3. An astronomical instrument, the limb of
which embraces a small portion only of a circle, used for measuring
differences of declination too great for the compass of a micrometer.
When it is used for measuring zenith distances of stars, it is called
a zenith sector.
Dip sector, an instrument used for measuring
the dip of the horizon. -- Sector of a sphere,
or Spherical sector, the solid generated by the
revolution of the sector of a circle about one of its radii, or, more
rarely, about any straight line drawn in the plane of the sector
through its vertex.
Sec"tor (?), n. [L., properly, a cutter,
fr. secare, sectum, to cut: cf. F. secteur. See
Section.] 1. (Geom.) A part of a
circle comprehended between two radii and the included arc.
2. A mathematical instrument, consisting of
two rulers connected at one end by a joint, each arm marked with
several scales, as of equal parts, chords, sines, tangents, etc., one
scale of each kind on each arm, and all on lines radiating from the
common center of motion. The sector is used for plotting, etc., to any
scale.
3. An astronomical instrument, the limb of
which embraces a small portion only of a circle, used for measuring
differences of declination too great for the compass of a micrometer.
When it is used for measuring zenith distances of stars, it is called
a zenith sector.
Dip sector, an instrument used for measuring
the dip of the horizon. -- Sector of a sphere,
or Spherical sector, the solid generated by the
revolution of the sector of a circle about one of its radii, or, more
rarely, about any straight line drawn in the plane of the sector
through its vertex.
