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The movable limb of a sextant or other angular instrument. Knight. Radius bar (Math.), a bar pivoted at one end, about which it swings, and having its other end attached to a piece which it causes to move in a circular arc. -- Radius of curvature. See under Curvature.

A straight line (or the length of such line) connecting any point, as of a curve, with a fixed point, or pole, round which the straight line turns, and to which it serves to refer the successive points of a curve, in a system of polar coördinates. See Coördinate, n.

One of the barbs of the hypoptilum, or aftershaft of a feather. See Feather.

In a curve referred to polar coördinates, any point for which the radius vector is a maximum or minimum.

sure of an angle (Math.), that in which the unit angle has its measuring arc equal to the radius of the circle.

One line or radius falling perpendicularly on another; as, the catheti of a right-angled triangle, that is, the two sides that include the right angle. Barlow.

means of its conservation. Burke. Conservation of areas (Astron.), the principle that the radius vector drawn from a planet to the sun sweeps over equal areas in equal times. -- Conservation of energy, or Conservation of force (Mech.), the principle that the total energy of any material system is a quantity which can…

he spine (Med.), an abnormal curving of the spine, especially in a lateral direction. -- Radius of curvature, the radius of the circle of curvature, or osculatory circle, at any point of a curve.

A circle described about the center of an elliptical orbit, with half the major axis for radius. Hutton.

One of the bones of either the forearm or shank, the epipodialia being the radius, ulna, tibia, and fibula.

on to the variable is the same as that of a certain straight line drawn in a circle whose radius is unity, to the length of a corresponding are of the circle. Let AB be an arc in a circle, whose radius OA is unity let AC be a quadrant, and let OC, DB, and AF be drawnpependicular to OA, and EB and CG parallel to OA, and…

to the center of the earth. Geocentric latitude (of place) the angle included between the radius of the earth through the place and the plane of the equator, in distinction from geographic latitude. It is a little less than the geographic latitude.

n the axis produced beyond the surface of the opposite hemisphere a distance equal to the radius of the sphere into the sine of 45º. -- Globular sailing, sailing on the arc of a great circle, or so as to make the shortest distance between two places; circular sailing.

the whorls of a spiral univalve shell. Center of gyration. (Mech.) See under Center. -- Radius of gyration the distance between the axis of a rotating body and its center of gyration. Rankine.

That part of an elliptical or many-centered arch which has the shorter radius and immediately adjoins the impost.

nce from the pole to the generating point varies inversely as the angle swept over by the radius vector.

A curve, traced by a point in the radius, or radius produced, of a circle which rolls upon the concave side of a fixed circle. See Hypocycloid, Epicycloid, and Trochoid.

of their distances from the center of the circle or sphere is equal to the square of the radius. -- Inverse, or Reciprocal, ratio (Math.), the ratio of the reciprocals of two quantities. -- Inverse, or Reciprocal, proportion, an equality between a direct ratio and a reciprocal ratio; thus, 4 : 2 : : , or 4 : 2 : : 3…

A spiral whose polar equation is r2th = a; that is, a curve the square of whose radius vector varies inversely as the angle which the radius vector makes with a given line.

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 object when viewed by either eye singly. Brande & C. -- Parallax of the cross wires (of an optical instrument), their apparent displacement when…