Conductor

(-dük'tur.) [Same der iv.) (Elect.) Abody capable of transmitting the electric fluid. It is called also a non-electric; for, unle insulated, it will not exhibit electrical excitement, the electricity being carried off along it as fast as it is communicated to or excited upon it. The metals are the best C.; resinous substances are very bad ones. Bodies incapable of transmitting electricity are called non-conductors; and, because electricity may be communicated to or excited upon them, without artificial insulation, they are termed electrics. There is no body a perfect conductor, or a perfect non-conductor. The non-conducting power depends very much on the extent of non-conducting surface. In frictional electricity, the best C. are the metals, as before stated; after which come graphite, sea-, spring-, and rain-water. Ice is a worse C. than fluid or water. Alcohol, ether, paper, dry wood, and straw, are also weak C. Shell-lac, wax, amber, and sulphur become C. when fused; and gla at a red heat conducts readily. A C. is said to bo insulated when it rests upon non-conducting supports. A LIGHTNING-C. is a pointed metallic rod fixed to the upper parts of buildings to secure them from the effects of lightning. It is connected with the earth, or, what is better, the nearest water, by a good conductor, which is sufficiently thick not to be melted in transmitting the electricity; and which, where attached to the wall, is insulated by non-conductors, so that the electricity may not be diverted to the building, instead of pa ing harmle ly away. This useful instrument was invented by Franklin in 1755. Conduit, (kon'dit.) [From L. conduco.] 'Arch.) A subterranean aqueduct; among the moderns, generally pipes of wood, iron, or tile, for conveying water from the main spring, or reservoirs, to the different places where it is required. (-doo'ple-kat.) (Bot.) Folded or doubled together, as certain leaves in the bud, especially the oak-leaf. The te rin is also applied to the embryo in a section of cruciferous plants, where the cotyledons are bent and the radicle is inclosed between their folds. (kōn'dil.) [Gr. kondylos, a knuckle.] (Anat.) A knuckle, or rounded protuberance at the end of a bone. The Condyloid Proce (sometimes called Condyle) is the posterior of the two protuberances which are placed at the upper side of the back of the under jaw. By this the jaw is articulated to the glenoid cavity of the temporal bone. The anterior of the protuberances is called the Coronoid proce . (kon.) [Gr. ko nos.] (Geom.) Asolid figure having a circle for its base, and its top terminating in a point or vertex, like a sugar-loaf, (A BC, Fig. 203.) A right C. has its axis perpendicular to its base, and its sides equal. It is supposed to be formed by the revolution of a rectangular plane triangle about one of its perpendicular sides. Any other C. is oblique. To find the curve surface of a C., multiply half of the product of the circumference of the base by the slant side. If the area of the base be added to this, the sum is the whole surface. The solidity ofa C. is ascertained by multiplying one-third of the product ofits base by its altitude. The frustum of a cone is that part which remains after cutting off the upper portion by a plane parallel to the base. To ascertain the solidity of such a frustum, add the squares of the diameters of the two ends to the product of the two diameters, and multiply the sum by the height and by 2618. A truncated C. is the lower part ofa C. cut by a plane parallel to the base.-(Bot.) The fruit of several trees forming the 0. Pinacea (Conifer a). 1 2 Fig. 202.- 1, PINUS MONTEZUME. 2, ITS CONE. It is composed of woody scales, variously shaped, each having a seed at the base.- CONE OF RAYS. (Opt.) The aggregate of the rays which proceed from aluminous point, or from a single point of a luminous object. [s. 216]