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d by the revolution of a tractrix. This surface corresponds in non-Euclidian space to the sphere in ordinary space. An important property of the surface is that any figure drawn upon it can be displaced in any way without tearing it or altering in size any of its elements.

A minute sphere composed of rhabdoliths.

A mass or ball of cells formed by the repeated division of a male germinal cell (spermospore), each constituent cell (spermoblast) of which is converted into a spermatozoid; a spermatogemma.

A young larval form of many annelids, mollusks, and bryozoans, in which a circle of cilia is developed around the anterior end.

A sphere which is smaller than, and in its movements subject to, another; a satellite.

To remove, as a planet, from its sphere or orb. Shak.

Of or pertaining to the air, or atmosphere; inhabiting or frequenting the air; produced by or found in the air; performed in the air; as, aërial regions or currents. "Aërial spirits." Milton. "Aërial voyages." Darwin.

A description of the air or atmosphere; aërology.

That department of physics which treats of the atmosphere.

The observation of the state and variations of the atmosphere.

true north; the line of no magnetic variation. There is one such line in the Western hemisphere, and another in the Eastern hemisphere.

The fluid which we breathe, and which surrounds the earth; the atmosphere. It is invisible, inodorous, insipid, transparent, compressible, elastic, and ponderable.

e often seen at great distances from the land. They are found chiefly in the southern hemisphere.

A small circle of the sphere parallel to the horizon; a circle or parallel of altitude. Two stars which have the same almucantar have the same altitude. See Almacantar. [Archaic] Almucanter staff, an ancient instrument, having an arc of fifteen degrees, formerly used at sea to take observations of the sun's amplitude a…

One of the rounded prominences of the lower surface of the lateral hemispheres of the cerebellum, each side of the vallecula.

An orthographic projection of the sphere on the plane of the meridian, the eye being supposed at an infinite distance, and in the east or west point of the horizon.

oid barometer, a barometer the action of which depends on the varying pressure of the atmosphere upon the elastic top of a metallic box (shaped like a watch) from which the air has been exhausted. An index shows the variation of pressure.

of two arcs of great circles, which mutually cut one another on the surface of a globe or sphere. -- Visual angle, the angle formed by two rays of light, or two straight lines drawn from the extreme points of an object to the center of the eye. -- For Angles of commutation, draught, incidence, reflection, refraction,…

Inhabitants of opposite hemispheres. Whewell.

A movement of the atmosphere opposite in character, as regards direction of the wind and distribution of barometric pressure, to that of a cyclone. -- An`ti*cy*clon"ic, a. -- An`ti*cy*clon"ic*al*ly, adv.