Polar circles(Astron. & Geog.), two circles, each at a distance from a pole of the earth equal to the obliquity of the ecliptic, or about 23° 28&prime, the northern called the arctic circle, and the southern the antarctic circle.Polar clock, a tube, containing a polarizing apparatus, turning on an axis parallel to that of the earth, and indicating the hour of the day on an hour circle, by being turned toward the plane of maximum polarization of the light of the sky, which is always 90° from the sun.Polar coördinates. See under 3d Coördinate.Polar dial, a dial whose plane is parallel to a great circle passing through the poles of the earth. Math. Dict.Polar distance, the angular distance of any point on a sphere from one of its poles, particularly of a heavenly body from the north pole of the heavens.Polar equation of a lineor surface, an equation which expresses the relation between the polar coördinates of every point of the line or surface.Polar forces (Physics), forces that are developed and act in pairs, with opposite tendencies or properties in the two elements, as magnetism, electricity, etc.Polar hare(Zoöl.), a large hare of Arctic America which turns pure white in winter. It is probably a variety of the common European hare (L. timidus).Polar lights, the aurora borealis or australis.Polar, or Polaric, oppositionor contrast(Logic), an opposition or contrast made by the existence of two opposite conceptions which are the extremes in a species, as white and black in colors; hence, as great an opposition or contrast as possible.Polar projection. See under Projection.Polar spherical triangle(Spherics), a spherical triangle whose three angular points are poles of the sides of a given triangle. See 4th Pole, 2.Polar whale(Zoöl.), the right whale, or bowhead. See Whale.

(Po"lar) n. (Conic Sections) The right line drawn through the two points of contact of the two tangents drawn from a given point to a given conic section. The given point is called the pole of the line. If the given point lies within the curve so that the two tangents become imaginary, there is still a real polar line which does not meet the curve, but which possesses other properties of the polar. Thus the focus and directrix are pole and polar. There are also poles and polar curves to curves of higher degree than the second, and poles and polar planes to surfaces of the second degree.

(Pol"ar*chy) n. See Polyarchy.

(Po*lar"ic) a. See Polar. [R.]

(Po"lar*i*ly) adv. In a polary manner; with polarity. [R.] Sir T. Browne.

(Po`lar*im"e*ter) n. [Polar + -meter.] (Opt.) An instrument for determining the amount of polarization of light, or the proportion of polarized light, in a partially polarized ray.

(Po`lar*im"e*try) n. (Opt.) The art or process of measuring the polarization of light.

(||Po*la"ris) n. [NL. See Polar.] (Astron.) The polestar. See North star, under North.

(Po*lar"i*scope) n. [Polar + -scope.] (Opt.) An instrument consisting essentially of a polarizer and an analyzer, used for polarizing light, and analyzing its properties.

(Po*lar`i*scop"ic) a. (Opt.) Of or pertaining to the polariscope; obtained by the use of a polariscope; as, polariscopic observations.

(Po`lar*is"co*py) n. (Opt.) The art or rocess of making observations with the polariscope.

(Po`lar*is"tic) a. Pertaining to, or exhibiting, poles; having a polar arrangement or disposition; arising from, or dependent upon, the possession of poles or polar characteristics; as, polaristic antagonism.

(Po*lar"i*ty) n. [Cf. F. polarité.]

1. (Physics) That quality or condition of a body in virtue of which it exhibits opposite, or contrasted, properties or powers, in opposite, or contrasted, parts or directions; or a condition giving rise to a contrast

their functions are not fully understood.

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