Part 150

Re*found" (r?*found"), v. t. [Pref. re- + found to cast; cf. F. refondare. Cf. Refund.] 1. To found or cast anew. "Ancient bells refounded." T. Warton.

2. To found or establish again; to re&?;stablish.

Re*found", imp. & p. p. of Refind, v. t.

Re*found"er (-?r), n. One who refounds.

Re*fract" (r?*fr$kt"), v. t. [imp. & p. p. Refracted; p. pr. & vb. n. Refracting.] [L. refractus, p. p. of refringere; pref. re- re- + frangere to break: cf. F. réfracter. SEe FRacture, and cf. Refrain, n.] 1. To bend sharply and abruptly back; to break off.

2. To break the natural course of, as rays of light orr heat, when passing from one transparent medium to another of different density; to cause to deviate from a direct course by an action distinct from reflection; as, a dense medium refrcts the rays of light as they pass into it from a rare medium.

Re*fract"a*ble (-?*b'l), a. Capable of being refracted.

Re*fract"ed, a. 1. (Bot. & Zoöl.) Bent backward angularly, as if half- broken; as, a refracted stem or leaf.

2. Turned from a direct course by refraction; as, refracted rays of light.

Re*fract"ing, a. Serving or tending to refract; as, a refracting medium.

Refracting angle of a prism (Opt.), the angle of a triangular prism included between the two sides through which the refracted beam passes in the decomposition of light. -- Refracting telescope. (Opt.) See under Telescope.

Re*frac"tion (r?*fr?k"sh?n), n. [F. réfraction.] 1. The act of refracting, or the state of being refracted.

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.

Refraction out of the rarer medium into the denser, is made towards the perpendicular.

Sir I. Newton.

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.

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.

Re*fract"ive (r?*fr?kt"?v), a. [Cf. F. réfractif. See Refract.] Serving or having power to refract, or turn from a direct course; pertaining to refraction; as, refractive surfaces; refractive powers.

Refractive index. (Opt.) See Index of refraction, under Index. -- Absolute refractive index (Opt.), the index of refraction of a substances when the ray passes into it from a vacuum. -- Relative refractive index (of two media) (Opt.), the ratio of the sine of the angle of incidence to the sine of the angle of refraction for a ray passing out of one of the media into the other.

Re*fract"ive*ness, n. The quality or condition of being refractive.

Re`frac*tom"e*ter (r?`fr?k*t?m"?*t?r), n. [Refraction + -meter.] (Opt.) A contrivance for exhibiting and measuring the refraction of light.

Re*fract"or (r&?;-fr&?;kt"&?;r), n. Anything that refracts; specifically: (Opt.) A refracting telescope, in which the image to be viewed is formed by the refraction of light in passing through a convex lens.

Re*frac"to*ri*ly (r?*fr?k"t?*r?*l?), adv. In a refractory manner; perversely; obstinately.

Re*frac"to*ri*ness, n. The quality or condition of being refractory.

Re*frac"to*ry (-r?), a. [L. refractorius, fr. refringere: cf. F. refractaire. See Refract.] 1. Obstinate in disobedience; contumacious; stubborn; unmanageable; as, a refractory child; a refractory beast.

Raging appetites that are Most disobedient and refractory.

Shak.

2. Resisting ordinary treatment; difficult of fusion, reduction, or the like; -- said especially of metals and the like, which do not readily yield to heat, or to the hammer; as, a refractory ore.