in general, is the deviation of a moving body from its direct course, occasioned by the different density of the media in which it moves; or it is a change of direction occasioned by a body's falling obliquely out of one medium into another. The word is chiefly made use of with regard to the rays of light. See Optics.

REFRACTION of Altitude, the arc or portion of a vertical circle, by which the altitude of a star is increased by the refraction of light.

REFRACTION of Ascension and Descension, an arc of the equator, by which the ascension and descension of a star, whether right or oblique, is increased or diminished by the refraction.

REFRACTION of Declination is an arc of a circle of declination, by which the declination of a star is increased or diminished by refraction.

REFRACTION of Latitude, an arc of a circle of latitude, by which the latitude of a star is increased or diminished by the refraction.

REFRACTION of Longitude, an arc of the ecliptic, by which the longitude of a star is increased or diminished by means of the refraction.

Terrestrial, is that which makes terrestrial objects appear to be raised higher than they are in reality, in observing their altitudes.