CHIMPANZEE 439 smoke. An inadequate admission of air into the room in which is the fireplace will cause a chimney to smoke, a circulating current being thus as effectually prevented as if the flue it- self were in great part obstructed. The open- ing of a door or window often shows the cause of this trouble by at once removing it. When two chimney flues come down into one room, or into two rooms which connect by an open passage, the burning of a fire in one flue may establish an upward current, which is supplied with air drawn down the other. Any attempts to make the second chimney draw could only succeed by closing the connection between them, or supplying the first with the air it re- quires from some other source. When a chim- ney smokes in consequence of the wind beating down, the height may be increased, or the di- ameter at the top contracted; but the most efficient remedy is usually found by adjusting a bent tube to the top of the chimney, and keeping its mouth turned in the direction of the current of air by means of a vane. The effect of the latter change is to admit a smaller quantity of air, and this is dispersed through the large body in the flue without being felt at the base. The worst chimneys usually draw well when a stove is substituted for the fireplace, and the pipe is led into the chimney. This causes an increased current in the smaller channel, being equivalent to contracting the throat of the chimney when the fireplace is used. Tall chimneys are built to convey away the noxious fumes from chemical and manufacturing estab- lishments, and relieve the neighborhood of the nuisance these would otherwise occasion. They are built up from a solid base, with side flues leading into the central cavity. The size of this cavity should, as in the chimneys of dwelling houses, be of rather larger area than the sum of that of the flues which lead into it. In large stacks it varies from 3 to 6 ft. in diameter. They are constructed with a brick lining, so laid as to leave an air space between it and the outer wall, the effect of this being to check the rapid dispersion of the warmth of the vapors. A chimney of this kind has been erected at Manchester, England, 415 ft. high, 25 ft. square at the base, and 9 ft. at the top. It required to build it 4,000,000 bricks. At the Thomas iron Vorks, on the Lehigh river in Pennsylvania, are cylindrical chim- neys of a thin boiler-plate iron casing, lined with fire brick ; the casing being 7 ft. in di- ameter, and the fire brick a foot long, made and bevelled to fit the circle, the internal di- ameter is 5 ft. These chimneys, for their ca- pacity, are light, substantial, and elegant ; but they are not built with reference to retaining the heat of the vapors, which is here no object. CHIMPANZEE (troglodytes niger, Geoff.), the form of the four-handed animals which comes the nearest to man ; so much so, indeed, that Linnaeus places it under the genus homo, with the epithet troglodytes to distinguish it from man. It differs from the orang outang in j having the cranium broader in proportion to the face ; in the characteristics of the skull ; in the smaller size of the incisor and canine teeth, and inferior development of the jaws, giving it a more human and less beast-like head ; in the difference of size in the vertebrae, the cervical being smaller and the lumbar larger in the chimpanzee ; in the possession of ad- ditional dorsal vertebra, corresponding to a second pair of ribs ; in the comparative short- ness of the forearm and hand ; in the greater proportional length of the femur and tibia, and the less proportional length of the foot ; and in many other points in the structure of the chest, loins, hands, nails, and fingers, extending in all to 23 points of difference in the osteological structure of the animals ; of these 23 points, 20 in the chimpanzee have a greater simi- larity than in the orang to the same points in the human being, and three in the orang have a greater similarity to those of man than the Chimpanzee (Troglodytes niger). 1. Hand of Chimpanzee. 2. Foot. 8. Skull. same in the chimpanzee. Owen well observes that from these considerations, and especially from the conformation of the jaws and dental system, which in the orang are scarcely in- ferior to those of the lion, and greatly resemble those of the fiercer and more terrible car- nivora, the chimpanzee ought to rank above the orang. The importance of these distinctions is not easily understood or appreciated from the reading of even the most lucid description, while it is seen in a moment by a glance at the skeletons of the animals, or at drawings' of them. The chimpanzee is a native of Africa only, and is found principally on the Congo and Guinea coasts, and in Gaboon. The length of the arms is very great, reaching be- low the knees by the whole extent of the fingers. The legs have a sort of calf, but it differs from that of the human being in that it continues of equal thickness nearly to the heel. The hand differs from that of man in having the thumb much the smallest of the
