資料來源 : Webster's Revised Unabridged Dictionary (1913)

Polar \Po"lar\, a. [Cf. F. polaire. See {Pole} of the earth.]
   1. Of or pertaining to one of the poles of the earth, or of a
      sphere; situated near, or proceeding from, one of the
      poles; as, polar regions; polar seas; polar winds.

   2. Of or pertaining to the magnetic pole, or to the point to
      which the magnetic needle is directed.

   3. (Geom.) Pertaining to, reckoned from, or having a common
      radiating point; as, polar co["o]rdinates.

   {Polar axis}, that axis of an astronomical instrument, as an
      equatorial, which is parallel to the earths axis.

   {Polar bear} (Zo["o]l.), a large bear ({Ursus, or Thalarctos,
      maritimus}) inhabiting the arctic regions. It sometimes
      measures nearly nine feet in length and weighs 1,600
      pounds. It is partially amphibious, very powerful, and the
      most carnivorous of all the bears. The fur is white,
      tinged with yellow. Called also {White bear}. See {Bear}.
      

   {Polar body}, {cell}, or {globule} (Biol.), a minute cell
      which separates by karyokinesis from the ovum during its
      maturation. In the maturation of ordinary ova two polar
      bodies are formed, but in parthogenetic ova only one. The
      first polar body formed is usually larger than the second
      one, and often divides into two after its separation from
      the ovum. Each of the polar bodies removes maternal
      chromatin from the ovum to make room for the chromatin of
      the fertilizing spermatozo["o]n; but their functions are
      not fully understood.

   {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[deg] 28', 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[deg] from the sun.

   {Polar co["o]rdinates}. See under 3d {Co["o]rdinate}.

   {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 line} or {surface}, an equation which
      expresses the relation between the polar co["o]rdinates 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} (Zo["o]l.), a large hare of Arctic America
      ({Lepus arcticus}), 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}, {opposition} or {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} (Zo["o]l.), the right whale, or bowhead. See
      {Whale}.

Projection \Pro*jec"tion\, n. [L. projectio: cf. F. projection.]
   1. The act of throwing or shooting forward.

   2. A jutting out; also, a part jutting out, as of a building;
      an extension beyond something else.

   3. The act of scheming or planning; also, that which is
      planned; contrivance; design; plan. --Davenant.

   4. (Persp.) The representation of something; delineation;
      plan; especially, the representation of any object on a
      perspective plane, or such a delineation as would result
      were the chief points of the object thrown forward upon
      the plane, each in the direction of a line drawn through
      it from a given point of sight, or central point; as, the
      projection of a sphere. The several kinds of projection
      differ according to the assumed point of sight and plane
      of projection in each.

   5. (Geog.) Any method of representing the surface of the
      earth upon a plane.

   {Conical projection}, a mode of representing the sphere, the
      spherical surface being projected upon the surface of a
      cone tangent to the sphere, the point of sight being at
      the center of the sphere.

   {Cylindric projection}, a mode of representing the sphere,
      the spherical surface being projected upon the surface of
      a cylinder touching the sphere, the point of sight being
      at the center of the sphere.

   {Globular}, {Gnomonic}, {Orthographic}, {projection},etc. See
      under {Globular}, {Gnomonic}, etc.

   {Mercator's projection}, a mode of representing the sphere in
      which the meridians are drawn parallel to each other, and
      the parallels of latitude are straight lines whose
      distance from each other increases with their distance
      from the equator, so that at all places the degrees of
      latitude and longitude have to each other the same ratio
      as on the sphere itself.

   {Oblique projection}, a projection made by parallel lines
      drawn from every point of a figure and meeting the plane
      of projection obliquely.

   {Polar projection}, a projection of the sphere in which the
      point of sight is at the center, and the plane of
      projection passes through one of the polar circles.

   {Powder of projection} (Alchemy.), a certain powder cast into
      a crucible or other vessel containing prepared metal or
      other matter which is to be thereby transmuted into gold.
      

   {Projection of a point on a plane} (Descriptive Geom.), the
      foot of a perpendicular to the plane drawn through the
      point.

   {Projection of a straight line of a plane}, the straight line
      of the plane connecting the feet of the perpendiculars let
      fall from the extremities of the given line.

   Syn: See {Protuberance}.