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lidated in the adult. -- Occipital point (Anat.), the point of the occiput in the mesial plane farthest from the ophryon.

tion of some other of the heavenly bodies; -- applied especially to eclipses of stars and planets by the moon, and to the eclipses of satellites of planets by their primaries.

A plane figure of eight sides and eight angles.

The position or aspect of a heavenly body, as the moon or a planet, when half way between conjunction, or opposition, and quadrature, or distant from another body 45 degrees.

er when in the part of the heavens directly opposite to it; especially, the position of a planet or satellite when its longitude differs from that of the sun 180º; -- signified by the symbol as, .

onal eyepiece, suspended vertically in gimbals by the object end beneath a fixed diagonal plane mirror. It is used for delineating landscapes, by means of a pencil at the eye end which leaves the delineation on paper.

A spherical body; a globe; especially, one of the celestial spheres; a sun, planet, or star. In the small orb of one particular tear. Shak. Whether the prime orb, Incredible how swift, had thither rolled. Milton.

rbiculate. -- Or*bic"u*lar*ly, adv. -- Or*bic"u*lar*ness, n. Orbicular as the disk of a planet. De Quincey.

on which is made by drawing lines, from every point to be projected, perpendicular to the plane of projection. Such a projection of the sphere represents its circles as seen in perspective by an eye supposed to be placed at an infinite distance, the plane of projection passing through the center of the sphere perpendic…

A name given to the two planes in the monoclinic system which are parallel to the vertical and orthodiagonal axes.

Of or relating to the time or act of rising; eastern; as, the ortive amplitude of a planet.

Osculatory circle. (Geom.) See Osculating circle of a curve, under Circle. -- Osculatory plane (to a curve of double curvature), a plane which passes through three successive points of the curve. -- Osculatory sphere (to a line of double curvature), a sphere passing through four consecutive points of the curve.…

team vessel, having paddles (or floats) on its circumference, and revolving in a vertical plane parallel to the vessel's length.

rve; one of the conic sections formed by the intersection of the surface of a cone with a plane parallel to one of its sides. It is a curve, any point of which is equally distant from a fixed point, called the focus, and a fixed straight line, called the directrix. See Focus.

rotation of a parabola about its axis; any surface of the second order whose sections by planes parallel to a given line are parabolas.

ance from a center. Paracentric curve (Math.), a curve having the property that, when its plane is placed vertically, a body descending along it, by the force of gravity, will approach to, or recede from, a fixed point or center, by equal distances in equal times; -- called also a paracentric. -- Paracentric motton or…

the body by lines drawn from it to the earth and sun; as, the heliocentric parallax of a planet. -- Horizontal parallax, the geocentric parallx of a heavenly body when in the horizon, or the angle subtended at the body by the earth's radius. -- Optical parallax, the apparent displacement in position undergone by an…

ded in the same direction, and in all parts equally distant; as, parallel lines; parallel planes. Revolutions . . . parallel to the equinoctial. Hakluyt.

The ratio of the three crystallographic axes which determines the position of any plane; also, the fundamental axial ratio for a given species.

With the lower focal points all in the same plane; -- said of sets of eyepieces so mounted that they may be interchanged without varying the focus of the instrument (as a microscope or telescope) with which they are used.