资料来源 : Webster's Revised Unabridged Dictionary (1913)

Positive \Pos"i*tive\, a. [OE. positif, F. positif, L.
   positivus. See {Position}.]
   1. Having a real position, existence, or energy; existing in
      fact; real; actual; -- opposed to negative. ``Positive
      good.'' --Bacon.

   2. Derived from an object by itself; not dependent on
      changing circumstances or relations; absolute; -- opposed
      to relative; as, the idea of beauty is not positive, but
      depends on the different tastes individuals.

   3. Definitely laid down; explicitly stated; clearly
      expressed; -- opposed to implied; as, a positive
      declaration or promise.

            Positive words, that he would not bear arms against
            King Edward's son.                    --Bacon.

   4. Hence: Not admitting of any doubt, condition,
      qualification, or discretion; not dependent on
      circumstances or probabilities; not speculative;
      compelling assent or obedience; peremptory; indisputable;
      decisive; as, positive instructions; positive truth;
      positive proof. ``'T is positive 'gainst all exceptions.''
      --Shak.

   5. Prescribed by express enactment or institution; settled by
      arbitrary appointment; said of laws.

            In laws, that which is natural bindeth universally;
            that which is positive, not so.       --Hooker.

   6. Fully assured; confident; certain; sometimes,
      overconfident; dogmatic; overbearing; -- said of persons.

            Some positive, persisting fops we know, That, if
            once wrong, will needs be always.     --Pope.

   7. Having the power of direct action or influence; as, a
      positive voice in legislation. --Swift.

   8. (Photog.) Corresponding with the original in respect to
      the position of lights and shades, instead of having the
      lights and shades reversed; as, a positive picture.

   9. (Chem.)
      (a) Electro-positive.
      (b) Hence, basic; metallic; not acid; -- opposed to
          {negative}, and said of metals, bases, and basic
          radicals.

   {Positive crystals} (Opt.), a doubly refracting crystal in
      which the index of refraction for the extraordinary ray is
      greater than for the ordinary ray, and the former is
      refracted nearer to the axis than the latter, as quartz
      and ice; -- opposed to negative crystal, or one in which
      this characteristic is reversed, as Iceland spar,
      tourmaline, etc.

   {Positive degree} (Gram.), that state of an adjective or
      adverb which denotes simple quality, without comparison or
      relation to increase or diminution; as, wise, noble.

   {Positive electricity} (Elec), the kind of electricity which
      is developed when glass is rubbed with silk, or which
      appears at that pole of a voltaic battery attached to the
      plate that is not attacked by the exciting liquid; --
      formerly called {vitreous electricity}; -- opposed to
      {negative electricity}.

   {Positive eyepiece}. See under {Eyepiece}.

   {Positive law}. See {Municipal law}, under {Law}.

   {Positive motion} (Mach.), motion which is derived from a
      driver through unyielding intermediate pieces, or by
      direct contact, and not through elastic connections, nor
      by means of friction, gravity, etc.; definite motion.

   {Positive philosophy}. See {Positivism}.

   {Positive pole}.
      (a) (Elec.) The pole of a battery or pile which yields
          positive or vitreous electricity; -- opposed to
          {negative pole}.
      (b) (Magnetism) The north pole. [R.]

   {Positive quantity} (Alg.), an affirmative quantity, or one
      affected by the sign plus [+].

   {Positive rotation} (Mech.), left-handed rotation.

   {Positive sign} (Math.), the sign [+] denoting plus, or more,
      or addition.

Eyepiece \Eye"piece`\, n. (Opt.)
   The lens, or combination of lenses, at the eye end of a
   telescope or other optical instrument, through which the
   image formed by the mirror or object glass is viewed.

   {Collimating eyepiece}. See under {Collimate}.

   {Negative}, or {Huyghenian}, {eyepiece}, an eyepiece
      consisting of two plano-convex lenses with their curved
      surfaces turned toward the object glass, and separated
      from each other by about half the sum of their focal
      distances, the image viewed by the eye being formed
      between the two lenses. it was devised by Huyghens, who
      applied it to the telescope. Campani applied it to the
      microscope, whence it is sometimes called {Campani's
      eyepiece}.

   {Positive eyepiece}, an eyepiece consisting of two
      plano-convex lenses placed with their curved surfaces
      toward each other, and separated by a distance somewhat
      less than the focal distance of the one nearest eye, the
      image of the object viewed being beyond both lenses; --
      called also, from the name of the inventor, {Ramsden's
      eyepiece}.

   {terrestrial}, or {Erecting eyepiece}, an eyepiece used in
      telescopes for viewing terrestrial objects, consisting of
      three, or usually four, lenses, so arranged as to present
      the image of the object viewed in an erect position.