Collier's New Encyclopedia (1921)/Meridian

MERIDIAN, a word connected in various ways with the idea of noon, or applied to the special conditions or culminating point in connection with a country, sphere of life, career, etc.

In geology: Noon-day; in allusion to the mid-day date of the strata to which it is applied. A term appropriated to certain middle formations of the Appalachian Palæozoic system, which are called in the New York Survey the Oriskany Sandstone, and which appear to be on the horizon of the Lower Ludlow rocks of England. The greatest thickness of this sandstone is less than 200 feet.

Celestial meridian: The great circle marked out on the srhere by the prolongation of the terrestrial meridian passing through the spot where the observer stands. Meridian altitude of the sun or of a star, altitude when on the meridian of the place where it is observed. Meridian distance of a point, the distance from the point to some assumed meridian, generally the one drawn through the extreme E. or W. point of the survey. Meridian of a globe, the brazen circle in which it turns and by which it is supported; also meridian lines drawn on the globe itself, generally at a distance of 15°. Terrestrial meridian, the terrestrial meridian of any place on the earth's surface is a great circle passing through both of the earth's poles and the place.