APPARENT PLACE of any Object, in Optics, is that wherein it appears, when seen through one or more Glasses.
See PLACE, OPTIC GLASS, etc.
The Apparent Place is different from the real one; for when, by Refraction through Glasses, that parcel of Rays which falls on the Pupil of the Eye, from each Point of any near Object, is made to flow as close together as that which comes from a distant one; or when, by the same means, the Rays coming from distant Objects are made to diverge as much as if they flowed from near ones; then the Eye must necessarily see the Place of the Objects changed.
This change is its Apparent Place. See VISION.
If an Object be placed nearer to a convex Glass than the Distance of its Focus; its Apparent Place may be determined. But if the Object be in the Focus of the Glass, the Locus Apparens of the Object cannot be determined; only that it will appear vastly remote.
Nor can the Locus Apparens be determined if the Object be beyond the Focus of a convex Glass. But if the Object be further distant from a convex Glass than its Focus, and the Eye lie beyond the distinct Base; its Apparent Place will be in the distinct Base. See the Article LENS. Apparent Place of a Star, etc., is a Point in the Surface of the Sphere determined by a Line drawn from the Eye, through the Centre of the Star, etc. See PLACE. The true, or real Place, is determined by a Line drawn from the Centre of the Earth, through the Star or Planet.
Apparent, or sensible Horizon, is that great Circle which limits our Sight; or the Place where the Heavens and the Earth seem to meet. See HORIZON.
It may be conceived as a Cone, whose Vertex is the Eye, and its Base the circular Plane which terminates our Prospect—It determines the Rising and the Setting of the Sun, Moon, or Stars. See RISING, SETTING, etc.
Apparent Conjunction, is when the right Line supposed to be drawn through the Centres of two Planets, does not pass through the Centre of the Earth, but through the Eye of the Spectator. See CONJUNCTION.
Apparent Motion, Time, etc. See MOTION, TIME, etc.
