Category:Spiral

Spi"ral, a. Etym: [cf. F. spiral. See spire a winding line.]

1. Winding or circling round a center or pole and gradually receding From it; as, the spiral curve of a watch spring.

2. Winding round a cylinder or imaginary axis, and at the same time Rising or advancing forward; winding like the thread of a screw; Helical.

3. (geom.)

Defn: of or pertaining to a spiral; like a spiral. Spiral gear, or Spiral wheel (mach.), a gear resembling in general a spur gear, but Having its teeth cut at an angle with its axis, or so that they form Small portions of screws or spirals. -- spiral gearing, a kind of gearing sometimes used in light Machinery, in which spiral gears, instead of bevel gears, are used to Transmit motion between shafts that are not parallel. -- spiral operculum, an operculum whih has spiral lines of growth. -- spiral shell, any shell in which the whorls form a spiral or Helix. -- spiral spring. See the note under spring, n., 4.

Spiral Spi"ral, n. Etym: [cf. F. spirale. See spiral, a.]

1. (geom.)

Defn: a plane curve, not reëntrant, described by a point, called the Generatrix, moving along a straight line according to a mathematical Law, while the line is revolving about a fixed point called the pole. Cf. Helix.

2. Anything which has a spiral form, as a spiral shell. Equiangular Spiral,a plane curve which cuts all its generatrices at the same Angle. Same as logarithmic spiral, under logarithmic. -- spiral of archimedes, a spiral the law of which is that the Generatrix moves uniformly along the revolving line, which also moves Uniformly.