declination
Refraction Re*frac"tion (r?*fr?k"sh?n), n. [F. r['e]fraction.] 1. The act of refracting, or the state of being refracted. [1913 Webster]

2. The change in the direction of ray of light, heat, or the like, when it enters obliquely a medium of a different density from that through which it has previously moved. [1913 Webster]

Refraction out of the rarer medium into the denser, is made towards the perpendicular. --Sir I. Newton. [1913 Webster]

3. (Astron.) (a) The change in the direction of a ray of light, and, consequently, in the apparent position of a heavenly body from which it emanates, arising from its passage through the earth's atmosphere; -- hence distinguished as atmospheric refraction, or astronomical refraction. (b) The correction which is to be deducted from the apparent altitude of a heavenly body on account of atmospheric refraction, in order to obtain the true altitude. [1913 Webster]

{Angle of refraction} (Opt.), the angle which a refracted ray makes with the perpendicular to the surface separating the two media traversed by the ray.

{Conical refraction} (Opt.), the refraction of a ray of light into an infinite number of rays, forming a hollow cone. This occurs when a ray of light is passed through crystals of some substances, under certain circumstances. Conical refraction is of two kinds; external conical refraction, in which the ray issues from the crystal in the form of a cone, the vertex of which is at the point of emergence; and internal conical refraction, in which the ray is changed into the form of a cone on entering the crystal, from which it issues in the form of a hollow cylinder. This singular phenomenon was first discovered by Sir W. R. Hamilton by mathematical reasoning alone, unaided by experiment.

{Differential refraction} (Astron.), the change of the apparent place of one object relative to a second object near it, due to refraction; also, the correction required to be made to the observed relative places of the two bodies.

{Double refraction} (Opt.), the refraction of light in two directions, which produces two distinct images. The power of double refraction is possessed by all crystals except those of the isometric system. A uniaxial crystal is said to be optically positive (like quartz), or optically negative (like calcite), or to have positive, or negative, double refraction, according as the optic axis is the axis of least or greatest elasticity for light; a biaxial crystal is similarly designated when the same relation holds for the acute bisectrix.

{Index of refraction}. See under {Index}.

{Refraction circle} (Opt.), an instrument provided with a graduated circle for the measurement of refraction.

{Refraction of latitude}, {longitude}, {declination}, {right ascension}, etc., the change in the apparent latitude, longitude, etc., of a heavenly body, due to the effect of atmospheric refraction.

{Terrestrial refraction}, the change in the apparent altitude of a distant point on or near the earth's surface, as the top of a mountain, arising from the passage of light from it to the eye through atmospheric strata of varying density. [1913 Webster]

The Collaborative International Dictionary of English. 2000.

Synonyms:

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• Declination — Dec li*na tion, n. [L. declinatio a bending aside, an avoiding: cf. F. d[ e]clination a decadence. See {Declension}.] 1. The act or state of bending downward; inclination; as, declination of the head. [1913 Webster] 2. The act or state of falling …   The Collaborative International Dictionary of English

• déclination — [deklinɑsjɔ̃] n. f. ÉTYM. XIIIe (astron.); déclination, lat. declinatio, du supin de declinare. → Décliner; comparer à déclinaison. ❖ ♦ Rare. 1 Action de décliner. 2 Vx. Pente …   Encyclopédie Universelle

• Declination — (v. lat.), 1) Abbeugung, Abneigung, Abweichung; 2) (Gramm.), die Art, wie ein Nomen zur Bezeichnung verschiedener Beziehungen (Casus) abgebeugt (declinirt) wird, wenn es überhaupt beugbar (Declinabile) u. nicht unbeugbar (Indeclinabile) ist, s. u …   Pierer's Universal-Lexikon

• declination — I noun abnegation, denial, disavowal, disclaimer, negation, nonacceptance, noncompliance, nonconsent, refusal, refusal of consent, rejection, renunciation, repudiation, unwillingness II index abandonment (repudiation), abatement (reduction) …   Law dictionary

• declination — late 14c. as a term in astronomy, from O.Fr. declinacion (Mod.Fr. déclinaison), from L. declinationem (nom. declinatio), noun of action from pp. stem of declinare (see DECLINE (Cf. decline)). It took on various other senses 15c. 17c., most now… …   Etymology dictionary

• declination — ► NOUN 1) Astronomy the angular distance of a point north or south of the celestial equator. 2) the angular deviation of a compass needle from true north …   English terms dictionary

• declination — [dek΄lə nā′shən] n. [ME declinacioun < L declinatio: see DECLENSION] 1. a bending or sloping downward; deviation from the horizontal or vertical 2. an oblique variation from some definite direction 3. the angle formed by a magnetic needle with …   English World dictionary

• Declination — For other uses, see Declination (disambiguation). In astronomy, declination (abbrev. dec or δ) is one of the two coordinates of the equatorial coordinate system, the other being either right ascension or hour angle. Declination in astronomy is… …   Wikipedia

• declination — declinational, adj. /dek leuh nay sheuhn/, n. 1. a bending, sloping, or moving downward. 2. deterioration; decline. 3. a swerving or deviating, as from a standard. 4. a polite refusal. 5. Astron. the angular distance of a heavenly body from the… …   Universalium

• declination — i. The angular difference in direction between magnetic north and true north, or between grid north and true north; hence, magnetic declination and grid declination. ii. The angular distance of a celestial body from the celestial equator along… …   Aviation dictionary

• declination — noun Etymology: Middle English declinacioun, from Middle French declination, from Latin declination , declinatio angle of the heavens, turning aside Date: 14th century 1. angular distance north or south from the celestial equator measured along a …   New Collegiate Dictionary