the open caisson, has no bottom, the edges of the sides resting directly on the surface. The upward extension of the structure is an open caisson within which the masonry is built on top, so that the weight causes the shoe, i.e., the lower edge of the vertical sides, to sink into the natural soil. In the working chamber, the floor of which is the bottom of the excavation, the roof the top of the caisson, and the walls the sides of the caisson, the material is excavated. From the working chamber, extending upward through the caisson and the masonry pier, is an air shaft, which affords the means of exit or entrance, while between the two is the air lock whose function is to retain the air pressure in the working chamber. Consult: Patton, A Practical Treatise on Foundations (New York, 1893); Fowler, Ordinary Foundations (New York, 1904, 1905); and for briefer treatment, Merriman, American Civil Engineers' Pocket Book (2d ed., New York, 1912). See FOUNDATION. See Dock for description of caissons used with dry docks.

CAISSON DISEASE, DIVER'S PALSY, "THE BENDS." A nervous disorder, the chief symptom of which is temporary paralysis, which attacks workers under high atmospheric pressure, on their return to the surface. The disease was first observed by Trizius in 1839, in men working in compressed air in cylinders; and by Pol and Watelle in 1845 in miners. The most frequent form of paralysis is paraplegia, but hemiplegia sometimes occurs. The symptoms vary widely in severity, depending on the length of time spent under high pressure, the rapidity of decompression and on the physical condition of the worker. Only physically sound men, free from diseases of the blood vessels, heart, lungs, and kidneys, should be selected for work in caissons. The discase is not often fatal, but paralysis may last for days or months, or remain permanent.

Authorities are not agreed as to the ultimate causes of the phenomena which attend an attack of the "bends." Among many theories, two find wide acceptance at present. According to one, the so-called gaseous theory, the blood becomes overcharged with oxygen and carbonicacid gas, which circulate therein as small bubbles, and which, endeavoring to escape through the lungs as pressure is relieved, either form emboli or penetrate into the surrounding tissues. The special effect of this pressure on the brain and spinal cord is due partly to their situation in closed bony cavities, and probably also to the delicacy of the nerve cells. When decompression takes place slowly, the gases have time to escape through the lungs, and evil effects are avoided. It has been shown experimentally by Seyler in 1855 and Paul Bert in 1872 that gas bubbles are produced in the blood of animals subjected to rapid changes in atmospheric pressure. According to the second theory, high pressure drives the blood from the surface to the deep organs, and especially to the cerebrospinal nervous system. Congestion ensues, followed by stagnation of the circulation. The blood vessels of the nervous system have little support, and do not readily recover their calibre and tone, so that stasis in the brain and cord lasts for a considerable time. Autopsy in recent fatal cases shows invariably congestion of the cord and brain; in later cases chronic softening of nerve tissues, such as occurs in myelitis.

In the treatment of caisson disease, morphia, heat, stimulants, strychnine, and ergot are recommended. Returning to compressed air for a time, and then emerging very slowly, is the common treatment. Prevention consists in increasing the time spent in "locking out" to one minute for every three pounds of pressure, thus avoiding a sudden transition from compressed air to the ordinary atmosphere pressure. Consult: Pol and Watelle, "Mémoire sur les effets de la compression de l'air," in Annales d'hygiène publique et de médicine légale (Paris, 1884); A. Gordon in Osler's Modern Medicine, vol. i (New York, 1907); Hill, Caisson Sickness, and the Physiology of Work in Compressed Air (London, 1912). See FOUNDATION.

CAITHNESS, kath'něs. The northernmost county of Scotland. Its area is nearly 697 square miles (Map: Scotland, E 1). The general aspect of Caithness is level and bare, it being in great part moorland and destitute of trees, while the seacoast is bold and rocky, with many bays, inlets, promontories, and caves. The chief crops are oats, barley, turnips, and potatoes. The occupants of the small farms divide their time between farming and herring, ling, cod, salmon, and lobster fishing. Wick, the county town, is the chief seat of the British herring fishery. Pop., 1801, 22,600; 1851, 38,700; 1891, 37,177; 1901, 33,860; 1911, 32,010. Consult Horne, The County of Caithness (London, 1907).

CAIUS, kēz, JOHN (1510-73). An English physician, the second founder of Gonville and Caius College, Cambridge. His real name was Kay, or Kaye, which he Latinized into Caius. He was born in Norwich, was educated at Gonville Hall, Cambridge, and, in medicine, at the University of Padua and elsewhere on the Continent, spending much time in search of accurate texts of Galen and Hippocrates. On his return he practiced at Cambridge, Shrewsbury, and Norwich. In 1547 he was elected a fellow of the College of Physicians, of which he was afterward nine times elected president. He also became physician to Edward VI, Queen Mary, and Queen Elizabeth. He acquired much wealth from the practice of his profession and employed it in the encouragement of science and learning. In 1557 he refounded Gonville Hall, thereafter known as Gonville and Caius College. In 1559 he was chosen master, and, although a Roman Catholic, retained office under Elizabeth. His books number 27 titles, including critical, antiquarian, and scientific works, the most famous of which is A Boke of Counseill Against the Sureat and Sweatyng Sickness (1552). Consult Works of John Caius, with a memoir of his life by J. Venn, edited by E. S. Roberts (New York, 1912).

CAIUS COLLEGE. See, GONVILLE AND CAIUS COLLEGE.

CA'IUS GRAC'CHUS. A tragedy by J. Sheridan Knowles, published in 1815 and produced at the Belfast Theatre, on February 13 of that year. Macready brought out a remodeled version on Nov. 18, 1823, at Covent Garden.

CAIVANO, ki-vä'no. A city in the Province of Naples, south Italy, 5 miles north of Naples, with which it is connected by a street railway (Map: Italy, J 7). The chief trade is in the grain, hemp, fruit, wine, and olives that grow in the vicinity, and there are manufactories of lime, glass, and casks. It was a place of considerable strength in the Middle Ages and still retains re

War Department (1761) and on the outbreak of hostilities with England in 1762 went to the front and fought in Portugal under the orders of the Count of Aranda. After the war he returned to the Council of War, whose dean he became in 1768.

CAJORI, kȧ-yo'rê, FLORIAN (1859- ). An American mathematician, born at St. Aignan, Switzerland. He came to the United States in 1875 and was educated at the University of Wisconsin, at Johns Hopkins, and at Tulane. After serving as assistant professor and professor of mathematics at the last-named institution from 1885 to 1888, he became identified with Colorado College, as professor of physics and of mathematics (1903), and dean of the School of Engineering. His publications include: The Teaching and History of Mathematics in the United States (1890); A History of Mathematics (1895); A History of Physics (1899); Introduction to the Modern Theory of Equations (1904; 1912); A History of the Logarithmic Slide Rule (1909).

CAKCHIQUEL, käk'chê-kal'. An important tribe or nation, of Mayan stock, formerly hold ing the central districts of southern Guatemala, where their descendants still reside. The name is that of a native tree, and their language is a dialect of the Quiche. At the time of their conquest by Alvarado, about 1524, they had at tained a high degree of culture, as is evidenced by their architectural remains, their calendar and hieroglyphic systems, and their native literary productions. They had an intense religious veneration for maize, and there is even reason to suppose that they were the first people to reclaim it from its original wild condition. The best compendium of their history and culture is Brinton's Annals of the Cakchiquels (Philadelphia, 1885). Consult also Stoll, Zur Ethnographie der Republik Guatemala (Zürich, 1884), and Thomas and Swanton, Indian Languages of Mexico and Central America (Washington, 1911).

CAKES, THE LAND OF. A title applied to Scotland, on account of the baps, scones, and oatmeal cakes which, with porridge, form the principal food of the country people. The epithet was prevalent in the eighteenth country.

CAKE URCHIN. See SAND DOLLAR; SEA URCHIN.

CALABAR BEAN, ORDEAL NUT. The seed of Physostigma venenosum, a twining, halfshrubby plant, native of western Africa, of the natural order Leguminosa, nearly allied to the kidney bean, but of a genus distinguished by the hood-shaped stigma and the deeply furrowed hilum of the seed. The bean itself is about the size of a large horse bean, with a firm, hard, brittle, shining integument, brownish red, pale chocolate, or ash gray in color; irregularly kidney-shaped, with two flat sides, and a furrow running longitudinally along its convex margin, ending in an aperture near one end of the seed. The kernel, consisting of two cotyledons, weighing about 46 grains is hard, white, and friable. It yields its virtues to alcohol and less perfectly to water. It is used in the form of an emulsion by the natives of Africa, as an ordeal when persons are suspected of witchcraft. It is believed that if the suspect vomits it he is innocent; if it is retained and death occurs, he is guilty. If the accused person is innocent, he will usually eat a large number without hesitation, and so cause vomiting; if

cur.

he hesitates and takes little, this does not ocThe bean contains two alkaloids-physostigmine, or eserine, which represents the chief activity of the drug and calabarine. In physiological doses physostigmine stimulates the secretion of the saliva, sweat, and tears; it stimulates also the involuntary muscles of the intestines, stomach, and bronchial tubes and diminishes the reflex activity of the spinal cord, being thus antagonistic to strychnine. Applied locally to the eye, it contracts the pupil, acting here as an antagonist to atropine (q.v.). In poisonous doses the activity of the respiratory centre in the cord and medulla is depressed or abolished, and death takes place from asphyxia. Physostigmine has been used medicinally in chorea, tetanus, and strychnine poisoning. It is employed in the form of the salicylate, to counteract the dilatation of the pupil caused by atropine, to lessen intraocular tension in glaucoma, and to alternate with atropine in breaking up adhesions in iritis.

CAL'ABAR RIVER. An estuary-like bay on the north side of the Bight of Biafra, which penetrates British Nigeria just west of the border line between it and Kamerun (Map: Congo Free State, A 2). It is about 10 miles wide and extends inland nearly 25 miles. Near the head of the bay the waters of three riversthe Cross, the Calabar, and the Akpa-are received through a deltoid borderland. The chief towns bordering the delta and estuary are Old Calabar, Duketown, and Creektown. The name "Old Calabar," employed in contradistinction to "New Calabar," a port and river 100 miles east, was officially replaced in 1904 by "Calabar."

CALABASH GOURD (Fr. calebasse, Sp. calabaza, a dry gourd; cf. Pers. kharbuz, melon, Little Kuss. harbuz, pumpkin, watermelon), or BOTTLE GOURD (Lagenaria vulgaris). A climbing annual plant of the family Cucurbitaceæ, cultivated in tropical countries. The angular leaves and the thin stem of the plant feel sticky to the touch and have a disagreeable odor. The odor of the white flowers resembles that of musk. The hard rind of the bottle-shaped fruit, called "calabash," is much used in tropical countries for holding liquids. The pulp of the common bottle gourd is worthless and cannot be used as an article of food. The calabash pipes imported from South Africa are made from the necks of these gourds. Other varieties of Lagenaria, however, bear an edible fruit, which is sometimes sweetened with sugar and offered for sale. For illustration, see Plate under CUCUM

BERS.

CALABASH TREE (Crescentia cujete). An evergreen tree found in the West Indies and in the tropical parts of America, belonging to the family Bignoniacea. In height and size it resembles an apple tree, and has broad lanceolate leaves, tapering to the base; large, whitish, fleshy flowers scattered over the trunk and older branches; and a gourdlike fruit, sometimes a foot in diameter. The wood of the tree is tough and flexible and is well adapted for coach making. The most useful part is the hard shell of the fruit, after the outer skin is removed. Under the name of calabash, it is much used, in place of bottles, for holding liquids, and for goblets, cups, water cans, etc. These shells may even be used as kettles for boiling liquids. They are sometimes highly polished, carved with figures, tinged with various colors, and converted into ornamental vessels. The rinds of gourds