watch (8 A.M. to noon), afternoon watch (noon to 4 P.M.), first dog watch (4 to 6 P.M.), second dog watch (6 to 8 P.M.), first watch (8 P.M. to midnight). The dog watches are designed to shift the order of the watch so that the same men will not have the same watch every night.

WATCH AND WARD. In the old English law a phrase employed to describe the supervision and care of police officials. Consult Blackstone's Commentaries, Book I, p. 356.

WATCHFUL FOX. See KEOKUK. WATCH HILL. See WESTERLY. WATCH OFFICER. Officers who have charge of the ship at sea are termed watch of ficers. The number of such officers depends upon the character of the vessel. In many large transatlantic steamers there are usually two officers on watch at a time. In large naval vessels the younger ensigns act as junior officers of the watch under the regular watch officers, who are lieutenants or ensigns of more experience. The watch officer actually on duty is called the officer of the deck or officer of the watch. WATER, H2O. A chemical compound of hydrogen and oxygen, formed by the union of two volumes of the former with one of the latter, or, what is the same, containing 11.136 per cent by weight of hydrogen and 88.864 per cent of oxygen. (See CHEMISTRY, especially historical section.) It is formed by the direct explosive union of its elements at a somewhat elevated temperature. This, however, need not be maintained, during the reaction, by the introduction of heat from outside sources; for the heat developed by the reaction itself (67,500 gram calories for every 18 grams of water formed) is not only sufficient to maintain the temperature necessary for combination, but, in the absence of indifferent gases or of an excess of one of the reacting gases, raises the temperature to 2844° C. (5151° F.). At this temperature about onethird of the reacting gases combine (see REACTION, CHEMICAL), the other two-thirds combining gradually during the subsequent cooling. The reaction may be started by platinum sponge or platinum black (forms of finely divided platinum), or other catalytic agents (see CATALY SIS), such as charcoal, pumice stone, porcelain, rock crystal, glass, etc.; with some of these substances, however, it is necessary besides to apply heat, although the initial temperature need not be quite so high as in their absence.

Liquid Water. Water is well known in the three states of aggregation-liquid, solid, and gaseous. Under normal atmospheric pressure, water is liquid between 0° C. (32° F.), its freezing point, and 100° C. (212° F.), its boiling point. Its greatest density is at about 4° C. (39.2° F.), at which temperature one cubic centimeter weighs, in vacuo, one gram. Its specific heat exceeds that of any other substance except hydrogen, the amount of heat required to raise the temperature of one gram from 18° to 19° C. being the most generally adopted unit of heat the so-called gram calorie. Water is difficultly compressible, 1,000,000 volumes becoming less by only 50 volumes when the atmospheric pressure is doubled. When viewed through layers of considerable height, pure water is seen to possess a bluish tinge. Soft potable waters have a brownish color. Water containing traces of calcium carbonate in suspension appears opaque if viewed through a sufficiently high column; but the opacity is gradually destroyed if carbonic acid gas is passed into the water, the color of the

latter meanwhile changing gradually through brown, yellow, and green, to blue. On the strength of this observation, it has been suggested that the colors of natural waters may be due in part to the varying amounts of carbonic acid contained by them, although the nature of the bottom and the color of the sky largely determine the color of waters, beyond doubt. Liquid water is a poor conductor of heat, and when perfectly pure is one of the poorest known conductors of electricity. The purification of water for scientific purposes is best effected by distillation. An efficient method consists in dissolving a small amount of potassium permanganate in a quantity of ordinary water, allowing it to stand for a day, then adding a further amount of potassium permanganate and some caustic potash and distilling, preferably in an apparatus provided with a platinum condenser (the metal of the apparatus must be free from lead); the first portions of the distillate should be rejected, and the distillation should be interrupted after about four-fifths has passed over; the intermediate portion may be further purified by dissolving in it a small amount of acid potassium sulphate and redistilling. Natural waters may be classified according to their origin. Rain water, which forms by the condensation of the aqueous vapor more or less abundant in the air, is the purest of all natural water, although it takes up foreign substances in its passage from the clouds to the earth, and always contains ammoniacal salts, sodium chloride, and other inorganic salts, as well as traces of organic matter of various kinds. Rain water collected in places where much coal is burned invariably contains traces of sulphuric acid derived from the oxidation of the sulphur from the pyrite present in most coals. Surface water, which includes the water from rivers, is of course less apt to be pure than rain water, its character being determined largely by the nature of the soil over which it passes, and by the vegetation on the surface. The mineral ingredients are usually carbonates, chlorides, and sulphates of the alkalies and alkaline earths, with small quantities of iron and manganese, while the organic matter is of vegetable origin. Well water is that derived from wells or bore holes made in the surface of the earth, and includes the water from shallow wells and that from deep wells. The shallow wells serve chiefly as the source of domestic supply, especially in country districts, and their water is liable to contamination from sewage and other refuse animal matter, owing to the fact that they are invariably sunk in the immediate vicinity of human dwellings. It is to such sources that epidemics of typhoid fever and similar diseases are often traced. Nitrates, nitrites, and ammonia are the constituents commonly found in such waters, and their presence indicates contamination of a dangerous character. Wells more than 100 feet in depth, and especially artesian wells, are used as sources of water, chiefly in cities, for manufacturing plants, which contains only mineral ingredients. Mineral waters (q.v.) possess more or less marked medicinal properties, in consequence of the considerable amounts in them of substances capable of exercising various physiological effects. Sea water is the water which forms the ocean; and as it is constantly receiving the waters more or less impure from rivers, and at the same time losing pure water in the form of vapor by means of evaporation, the impurities

remain behind, and have given to this water its well-known saline character. An analysis of sea water shows traces of nearly every known element; its salinity varies in different parts of the world. When it freezes the resulting ice is practically free from salt. Waters are distinguished as hard and soft according as they contain large or small quantities of calcium or magnesium salts in solution, and this fact may be determined by an examination with a soap solution, the addition of which causes the formation of lather when the quantity added is sufficient to have rendered the water soft.

Ice or Solid Water. The passage of water from the liquid to the solid state is accompanied by an expansion equal to about one-eleventh of its volume; hence water freezing in pipes may easily cause them to burst. The normal freezing point of water varies but slightly with the external pressure; considerable pressures, however, cause a marked depression of the freezing point. (See FREEZING POINT; MELTING POINT.) Besides, if carefully kept out of contact with the air, water may be readily undercooled to temperatures far below its freezing point; it is then, however, in an exceedingly unstable state, and mere contact with a sharp-edged body, or especially exposure to the air, causes the entire mass to freeze very rapidly, the temperature simultaneously rising to the normal freezing point. The heat developed during the freezing of one gram of water is 79.06 calories. Natural ice is transparent and highly coherent. Ice of similar properties is obtained artificially when the cooling medium employed is only about one degree below the freezing point; the ice formed at lower temperatures occludes minute globules of air, and these render it whitish and more or less opaque. Besides ordinary ice, water forms several other forms of ice, discovered by Tammann and by Bridgman (see ICE). Bridgman's "Ice V," which can exist only under high pressures, can be heated to nearly 80° C. (176° F.) without melting.

Water Vapor, or Gaseous Water. This is a normal constituent of the atmosphere (q.v.). The passage of one gram of liquid water into steam at 100° C. (212° F.) involves the absorption of as much as 536 calories of heat. At every temperature water vapor can only exist below a certain maximum of pressure, viz., the vapor pressure of water at that temperature. Under that pressure the vapor is said to be saturated. Stronger pressure causes liquefaction, unless the temperature is above the critical point, which, according to Battelli, is about 364° C. (about 687.7° F.). (See CRITICAL POINT.) Water vapor is colorless and perfectly transparent, unless it is allowed, in the saturated state, to escape into the cold air, when condensation causes the formation of minute bubbles that produce the characteristic appearance of steam.

Bibliography. P. P. Dehérain, Etudes pour servir à l'histoire de la chimie: La découverte de la composition de l'eau (Paris, 1860); W. R. Nichols, Water Supply (New York, 1883); Floyd Davis, An Elementary Handbook on Potable Water (Boston, 1891); Greenwell and Curry, Rural Water Supply (London, 1895); J. H. Fuertes, Water and Public Health (New York, 1897); W. P. Mason, Water Supply (3d ed., ib., 1909); William Coles-Finch, Water: Its Origin and Use (ib., 1909); Ferdinand Fischer, Das Wasser: Seine Gewinnung, Verwendung, und

Beseitigung (Leipzig, 1914). Analysis: M. N. Baker, Potable Water and Methods of Detecting Impurities (2d ed., New York, 1906); Wanklyn and Chapman, Water Analysis (11th ed., London, 1907); W. W. Clemesha, Bacteriology of Surface Waters in the Tropics (New York, 1913); Prescott and Winslow, Elements of Water Bacteriology (3d ed., ib., 1913); J. C. Thresh, Examination of Waters and Water Supplies (2d ed., Philadelphia, 1913); G. C. Whipple, Microscopy of Drinking Water (3d ed., New York, 1914); Henry Leffmann, Examination of Water for Sanitary and Technical Purposes (7th ed., Philadelphia, 1915). See WATER PURIFICATION; WATER SUPPLY; WATER WORKS; WELL SINKING; ETC.

WATER, HOLY. See HOLY WATER. WATER, MINERAL. See MINERAL WATER. WATER AVENS. See GEUM.

WATER BABIES, THE. A fanciful tale by Charles Kingsley (1863).

WATER BEAR, or BEAR ANIMALCULE. TARDIGRADA,

See

WATER BED. A rubber bed-tick, designed to be filled with water and to take the place of an ordinary mattress on a sick bed. Its use decreases the probability of the formation of bed sores (q.v.). Objections to it are its great weight when filled, its liability to become cold, thus chilling the patient, and the difficulty of drawing off the contents and replacing them with warmer water. The air mattress, constructed on the same principle, meets all the requirements and is free from the foregoing objections. It is provided with a valve stem through which it may be inflated with an air pump. WATER BEECH. See HORNBEAM.

WATER BEETLE. Any beetle which lives in or upon the water; more specifically, one of the true water beetles or water tigers of the family Dytiscidæ. They live in the water both as larvæ and as adults, although they are probably modified terrestrial insects resembling the ground beetles of the family Carabidæ. The pupa is terrestrial. They are elliptical convex insects with the hind legs formed for swimming. The wing cases fit perfectly to the body except at the tip, so as to form an air-tight space above the body proper. This space is the air chamber, and the beetle rises to the surface of the water, exposing the tip of its body and drawing in a supply of air which will last it for some time, when it goes below the surface again. larvæ of the true water beetles are very rapacious, and suck the juices of small, soft aquatic insects. The mandibles are hollow, with a hole near the tip and another at the base, thus being fitted for suction. The water beetles are more numerous in temperate and boreal than in tropical regions. About 2000 species are known, of which nearly 400 inhabit the United States.

The

Whirligig beetles of the family Gyrinidæ are small oval forms which swim about on the surface of the water, usually darting in curious curves, from which habit the popular name is derived. They can dive, carrying with them a small supply of air, but their proper life is on the surface. The two hind pairs of legs are so modified as to form paddles. The larvæ are aquatic and are elongate with sharp mandibles. They are carnivorous in the larval stage as well as in the adult. About 350 species are known, of which nearly 40 occur in the United States.

The water beetles of the family Hydrophilida are sometimes called water scavenger beetles. The larvæ are predaceous and carnivorous, but

the adult beetles are, as a rule, vegetable feeders, though they will prey upon small aquatic animals. They are usually dark-colored, of elliptical shape, and do not swim as readily as do the other water beetles, nor is the supply of air which may be carried as extensive as with the others. Many species construct egg cocoons, which are sometimes attached to the body of the beetle and sometimes to aquatic plants, and frequently unattached, floating on the surface of the water. From 20 to 100 eggs are laid in each cocoon. About 1200 species are known, and of these 175 are found in the United States and about 90 in England. Other beetles, such as the Amphizoida and Pelobiidæ, live in the water in their early stages. The strangely modified parasitic beetle, Platypsyllus castoris, found commonly upon the beaver, might also with justice be called a water beetle. Consult L. C. Miall, The Natural History of Aquatic Insects (London, 1895), and V. L. Kellogg, American Insects (2d ed., New York, 1908).

WATER BIRDS. A group of birds alike in their adaptations to an aquatic life. Such are the sea birds, or Steganopodes, as the cormorant; the auk tribe, gull tribe, and other marine groups; and the great tribe of fresh-water aquatic birds represented by the swans, geese, and ducks. Water birds are swimmers and divers, and are more or less completely web-footed, thus being furnished with paddles and with broad supports in walking upon muddy shores. All get their food mainly from the water-fish, amphibians, reptiles, shellfish, and small aquatic animals, or else aquatic vegetation. Their plumage is dense, oily, and, except in the ducks, usually of plain black, white, and brown colors; they nest on the ground, as a rule, laying unspotted eggs, except auks, gulls, etc.; the freshwater section affords many birds esteemed for food and sport, and several domesticated species of great value. Consult S. F. Baird and others, History of North American Water Birds (2 vols., Boston, 1884), and H. K. Job, Among the WaterFowl (New York, 1902). See Colored Plate of WATER BIRDS.

WATER BOATMAN. An aquatic bug of the family Corixida, in which the head is free, capable of great rotation, and attached to the thorax only by a narrow area. The water boatmen are mottled bugs of oval shape found swimming on the surface of ponds and streams. They are at home beneath the water as well as on the surface, and remain there for a long time, since the fine body hairs retain a film of air. They hibernate in mud at the bottom of ponds or streams. The eggs are laid under water, and are attached to stems of aquatic plants. When their pools dry up they fly to other water, and are sometimes attracted to lights at night. About 40 species occur in the United States, all belonging to the genus Corixa. The eggs of Corixa mercenaria and Corixa femorata are laid in enormous numbers in the lakes near the city of Mexico, and are made into cakes with meal by natives and half-breeds. The adults also are eaten in Mexico and in Egypt.

WATERBRASH. See PYROSIS.

WATER BUCK, or KOB. One of the large marsh-loving African antelopes of the genus Cobus or Kobus, several species of which go by other names, as singsing (q.v.). The water buck proper (Cobus ellipsiprymnus) is more than four feet tall, and remarkable for its long, shaggy, reddish coat. It is numerous all over

southern and eastern Africa, roving in small bands about stony hills near the marshy rivers, to which it runs for refuge when alarmed. Its flesh is very poor eating. See Plate of ANTE

LOPES.

WATER BUFFALO. See BUFFALO.

WATER BUG. In general terms, any aquatic insect of the order Hemiptera, including all of the members of the six families composing the group Cryptocerata or Hydrocorisæ, as well as the Hebridæ and Hydrobatidæ. (See WATER STRIDER.) The families Corixida (see WATER BOATMAN), Nepida (see WATER SCORPION), Galgulida (see TOAD BUG), and Belostomidæ (see FISHKILLER) belong to this group.

The back swimmers of the family Notonectidæ are predaceous water bugs resembling the water boatmen, but the dorsum is very convex and they always swim with the ventral surface upward, a habit which distinguishes them from all other water bugs. The female pierces holes in the stems of water plants for her eggs. The adults hibernate in mud at the bottom of streams and ponds. About a dozen species are known in the United States. These as well as water boatmen are sometimes known as boat flies, as they occasionally leave the water and fly around lights at night. The creeping water bugs of the family Naucorida are small, flatbodied, oval water bugs found in ponds containing plenty of vegetation, on which the creepers crawl or about which they swim, feeding upon land insects which have accidentally fallen into the water. The marsh treaders of the family Hydrometridæ resemble the water striders, but are more slender and delicate. The adults of the commonest species (Hydrometra lineata) hibernate under rubbish along the banks of slow streams and ponds, and lay their eggs singly on the stems of aquatic plants. The larvæ fall into the water and remain near the bank, feeding upon the bodies of insects which fall into the stream. The only other true bugs which are in any way aquatic belong to the family Hebridæ, which contains very small species of semiaquatic habits, found in wet moss and littoral vegetation. The common cosmopolitan German cockroach or croton bug (Ectobia germanica) is often called water bug in the United States, since it is found near water pipes in houses. See COCKROACH.

WATERBURY, wa'ter-běr-i. A city and one of the county seats of New Haven Co., Conn., 33 miles southwest of Hartford, on the Naugatuck River and on the New York, New Haven, and Hartford Railroad (Map: Connecticut, C 3). It is attractively situated in the heart of the Naugatuck valley. There are four parks

Centre Square, Hamilton, Chase and Union Square, and Riverside Cemetery of great natural beauty. Among the educational institutions are St. Margaret's Diocesan School for Girls (Episcopal), the Convent of Notre Dame, and the Gerard School. Noteworthy features include: the Silas Bronson Library (97,000 volumes), the Mattatuck Historical Society collection of paintings, historical statuary and medallions, Mulcahy Memorial Hall, the Municipal Building, Union Station, the Federal Building, Elton Hotel, and the county courthouse. The Eagles and Elks orders have homes here. Among the charitable institutions are St. Mary's and Waterbury hospitals, Southmayd Home for Old Ladies, and two day nurseries. Waterbury has large industrial interests. It is the leading centre of the United States for the manufacture