DISC

, or Disk, the body or face of the sun or moon; such as it appears to us; for though they be really spherical bodies, they are apparently circular planes.

The diameter of the disc is considered as divided into 12 equal parts, called digits; by means of which it is, that the magnitude of an eclipse is measured, or estimated.—In a total eclipse of either of those luminaries, the whole disc is obscured, or darkened; in a partial eclipse, only part of them.

Illuminated Disc of the Earth. See Circle of Illumination.

Disc

, in Optics, the magnitude of a telescope glass, or the width of its aperture, whatever its figure be, whether a plane, convex, meniscus, or the like.

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Entry taken from A Mathematical and Philosophical Dictionary, by Charles Hutton, 1796.

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DIOPTRICS
DIRECT
DIRECTION
DIRECTLY
DIRIGENT
* DISC
DISCHARGER
DISCORD
DISCOUNT
DISCRETE
DISDIAPASON