CONE. (1) In geometry, the solid figure traced out when a right-angled triangle is made to revolve round one of the sides that contain the right angle; this is more strictly a right cir cular cone. A more comprehensive definition may be given as follows: Let a straight line be held fixed at one point and let any other point of the line be made to describe any closed curve which does not cut itself ; the solid figure traced out is a cone. The moving line is known as a generating line or generator of the cone. When the axis of the cone, that is, the line joining the fixed point to the centre of symmetry of the closed curve, is perpendicu lar to the plane of the base, the cone is right; and when in addition the curve which the sec ond point describes is a circle, the cone is a right circular cone. Cones whose axis are in clined to their bases at any angle other than a right angle are known as oblique cones. If a cone be cut in two by a plane parallel to the base, the lower portion is called a frustum or a truncated cone. The geometry of the cone is important on account of the curves called conic sections, which are obtained by cutting a right circular cone by planes in various directions. The cubic content of a cone is one-third of that of a cylinder on the same base and of the same altitude. The cubical content of the cone is therefore found by multiplying the area of the base by the altitude and taking one-third of the product. The area of the slant or curved surface of a right circular cone is ob viously equal to that of a sector of a circle of radius equal to the slant height, an arc equal to the circumference of the base. It is there fore obtained by multiplying the slant height by the circumference of the base and taking one-half of the product.
(2) In botany, a dry compound fruit, con sisting of many open scales, each with two seeds at the base, as in the conifers; a strobilus.
(3) In geology, the heap or mountain of ash, cinders and lava piled up around a vol canic vent. Small cones on the flanks of larger
ones are called parasitic. The term cone is also applied to the mound of silicious sinter (q.v.) built up around a geyser. See GEYSERS; MOUNTAINS; VoLcANo; and the section on Vol canism in the article on GEOLOGY.
A true bug (Conorhinus sanguisugus) of the family Reduvsidee, related to the bedbugs and having similar habits in the South; it is nearly an inch long and black, blotched with red. In 1898 much excitement was occasioned in the North by newspaper ac counts of attacks by "kissing-bugs," which were two related species, Opisoccetus persona tus and Melanolestes picipes, the former fre quently found in dirty houses feeding upon cockroaches, bedbugs, etc., and breeding in dusty corners. The bite is painful, but not poisonous.
or CONIDIE, a family of ctenobranchiate Gastropoda, so called on ac count of their form. All the cones have a similar external outline; the aperture is long and narrow, the head of the living animal is more or less lengthened, the proboscis elon gated, the foot is splay and abruptly cut off in front, the tentacles are rather widely separate and the eyes are placed on these organs. All of the species are carnivorous. Several hun dred species have been described, about one fifth of them from tropical American waters. Owing to their beauty and variety the cones are much sought by collectors, who pay ex travagant prices for the rarer forms. The tex tile cone-shells (Conus textilis), brought from Mauritius, a handsome species four or five inches in length, are marked with narrow, an gular lines of dark brown, variegated with dashes of yellow and irregular white spots. They haunt the fissures and holes in rocks and warmer pools in coral reefs. They all take a moderate range of depth, varying from 1 to 40 fathoms.