in Geometry, a projection of the sphere on the plane of the meridian, orthographically made by a straight line and ellipses, the eye being supposed at an infinite distance, and in the east or west point of the horizon.

ANALEmma denotes likewise an instrument of brass or wood, upon which this kind of projection is drawn, with an horizon or cursor fitted to it, wherein the solstitial colure, and all circles parallel to it, will be concentric circles; all circles oblique to the eye will be ellipses; and all circles whose planes pass through the eye will be right lines. The use of this instrument is to show the common astronomical problems; which it will do, though not very exactly, unless it be very large.