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. Camber arch (Arch.), an arch whose intrados, though apparently straight, has a slightly concave curve upward. -- Camber beam (Arch.), a beam whose under side has a concave curve upward.

An apparatus in which the images of extermal objects, formed by a convex lens or a concave mirror, are thrown on a paper or other white surface placed in the focus of the lens or mirror within a darkened chamber, or box, so that the oulines may be traced.

Two small, concave shells of ivory or hard wood, shaped like spoons, fastened to the thumb, and beaten together with the middle finger; -- used by the Spaniards and Moors as an accompaniment to their dance and guitars.

A concave molding; -- used chiefly in classical architecture. See Illust. of Calumn.

or more sides. The columns are often fractured transversely, with a cup joint, showing a concave surface above. This structure is characteristic of certain igneous rocks, as basalt, and is due to contraction in cooling.

rp.), a plane, convex in the direction of its length on the under side, for smoothing the concave faces of curved woodwork. -- Compass plant, Compass flower (Bot.), a plant of the American prairies (Silphium laciniatum), not unlike a small sunflower; rosinweed. Its lower and root leaves are vertical, and on the prairi…

The act of making concave.

A concave surface, or the space bounded by it; the state of being concave.

Concave on one side and convex on the other, as an eggshell or a crescent.

Concave. Abp. potter. -- Con*ca"vous*ly, adv.

at the end of a bone bearing a rounded articular surface; -- sometimes applied also to a concave articular surface.

ed that rays from the focus of one are received at the focus of the other, especially two concave mirrors so placed that rays proceeding from the principal focus of one and reflected in a parallel beam are received upon the other and brought to the principal focus. -- Conjugate point (Geom.), an acnode. See Acnode, an…

-- said of a spherical surface or curved line when viewed from without, in opposition to concave. Drops of water naturally form themselves into figures with a convex surface. Whewell. Double convex, convex on both sides; convexo-convex.

Anything regarded as extended over the head, as the arch or concave of the sky, the roof of a house, the arch over a door. "The starry cope of heaven." Milton.

of connective tissue. Quain's Anat. Red blood corpuscles (Physiol.), in man, yellowish, biconcave, circular discs varying from 1/3500 to 1/3200 of an inch in diameter and about 1/12400 of an inch thick. They are composed of a colorless stroma filled in with semifluid hæmoglobin and other matters. In most mammals the re…

A concave molding.

A cove or series of coves, as the concaved surface under the overhang of a projecting upper story.

The increasing moon; the moon in her first quarter, or when defined by a concave and a convex edge; also, applied improperly to the old or decreasing moon in a like state.

A hood-shaped organ, resembling a cowl or monk's hood, as certain concave and arched sepals or petals.

To make concave or in the form of a cup; as, to cup the end of a screw.