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COMBUSTION 83 COMET The stamens are generally twice as many as the segments of the calyx; the ovary one-celled, 2-4 pendulous ovules, style 1, stigma simple. The order is divided into three tribes: termmulese, covibretese, and gyrocarpeai. The myro- balans are found within the tropics of Asia, Africa, and America. COMBUSTION, the act of burning, the state of being burned. Spontaneous Combustion is Combustion occurring without any means taken on the part of man to produce it. A Combustion of the human body produced by occult in- ternal causes is alleged to have occurred several times. Most chemists believe the Combustion of the human body in the way described an impossibility. COMEDIE FBANCAISE, the national subsidized theater of France, formed in 1680 by the fusion of the two bodies into which Moliere's company of actors had split. It is at present managed by regulations made in 1812, modified by subsequent resolutions. COMEDIETTA, a dramatic composi- tion of the comedy class, but not so much elaborated as a regular comedy, and generally consisting of one or at most two acts. COMEDONES, a name applied to the little cylinders of sebaceous and epithe- lial substance which are apt to accumu- late in the follicles of the skin and to appear on the surface as small round black spots. When squeezed out they have the appearance of minute mag- gots or grubs, with black heads, and thence have derived their name. COMEDY, a dramatic representation of a light and amusing nature, in which are satirized pleasantly the weaknesses or manners of society and the ludicrous incidents of life. Comedy took its origin in the Dionysian festivals, with those who led the phallic songs of the band of revelers (Gr., kdmos) who, at the vintage festivals, gave expression to the exuberant joy and merriment by parad- ing about, dressed up, and singing jovial songs in honor of Dionysus. Comedy first assumed a regular shape among the Dorians. The first attempts at it among the Athenians were made by Susarion, a native of Megara, about 578 B. c. Epicharmus first gave comedy a new form and introduced a regular plot. That branch of the Attic drama known as the Old Comedy begins properly with Cratinus. It lasted from 458 B. c. to 404 B. c. The later pieces of Aristoph- anes belong to Middle Comedy. The most distinguished of Roman comic writers were Plautus and Terence. COMET, a luminous heavenly body which, in general, consists of a nucleus or "head" with, or frequently without, a tail, the whole moving in the heavens, first toward, then around, and finally away again from the sun, like a planet at one part of its elliptic orbit. Comets have in every age excited attention, and, till recently, have inspired terror in the general public, or at least in ignorant minds. Tycho Brahe, about 1577, showed that a certain comet was at a greater distance from the earth than the moon. Hevelius, in 1668, ascertained that the orbit of a comet was concave and not a straight line, the latter erro- neous view having been held by Tycho Brahe, already mentioned, and Kepler. Doerfel (1861) believed comets to move in parabolas. In 1682 Halley proved the comet, subsequently called after him, to be periodic in its returns. In 1704 Sir Isaac Newton proved comets to obey the law of gravitation, and held that in all probability they moved in elliptic orbits. Present state of knowledge and opin- ion. — More than 600 comets, according to J. R. Hind, have been taken note of, but about 17,500,000 are believed to exist in connection with the solar system. The head or nucleus is much less solid than it seems. Thus, in 1832, Sir John Herschel saw a group of stars only of the 16th magnitude, almost through the center of Biela's comet. When such a body might be expected to exercise gravitation its influence is too small to be perceptible. Regarding orbit, the comets may be divided into two very distinct classes: First, those whose orbits are so long that they are usually regarded as parabolas, and second, those whose orbit and period are both short. Of the latter class, about 12 or 15 are known. The first seem to have come to us from outside space; the sec- ond set, originally belonging to the former, to have had their direction changed so as to produce their present short elliptic orbits by the action on them of some planet. In 1866 Professor Schiaparelli, of Milan, discovered that the orbit of Tuttle's comet, the third which had appeared in 1862, was nearly identical with that of the August me- teors, and Tempel's comet, the first of 1866, with that of the November me- teor stream. In consequence of this dis- covery, Prof. P. G. Tait published the view that the sudden development of tails many millions of miles in length, the occurrence of comets with many tails, and the observed fact that there is no definite relation of direction be- tween a comet's tail and its solar radius