APPARENT, a term employed by mathe maticians and astronomers to denote things as they appear to the eye in distinction from what they really are. Thus they speak of apparent motion, magnitude, distance, height, time, etc. So important is this difference between reality and appearance, particularly in regard to the heavenly bodies, that we find all early astron omers, who were ignorant of this fact, run ning into error; and a great ad vancement in science was required before man kind was able to establish systems opposed to appearances. Every one knows that a body may appear to move while it is, in fact, at rest, and the motion is in the spectator, or the place on which he stands, as is the case with the sun in relation to the inhabitants of this earth. The apparent altitude of a heavenly body is what appears to be its angle of elevation above a horizon which may itself be apparent — that is, the seeming junction of sea and sky; or (sensi ble"— that is, a plane passing through the point of observation at right angles to the plumb line; or true — that is, a plane parallel to the horizon and passing through the centre of the earth. When the altitude of a
heavenly body is measured corrections are made for refraction, parallax, and, if the measurement is from a visible sea horizon, for the height of the observer above the water.
The phrase heir apparent signifies one whose right of inheritance is indefeasible pro vided he survive his ancestor; as the eldest son or his issue, who must, by the course of the common law, be heirs to the father. Heirs presumptive are those who, if the ancestor should die immediately, would in the existing state of things be his heirs.