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Consult: Blanford, Fauna of British India: Mammals (London, 1888-91); Zoology of Abyssinia (London, 1870); and the writings of sportsmen-travelers in Africa and India. See Plate of HYENAS.

HYENA DOG. See HUNTING DOG.

HYÈRES, é'âr'. A town in the Department of Var, France, three miles from the Mediterranean and eight miles east of Toulon (Map: France, N 8). It is a fashionable winter resort picturesquely situated on the southern slope of a castle-crowned hill 670 feet high, in a district noted for its mild climate, sheltered location, and luxuriant vegetation. Its chief buildings are the restored twelfth-century cathedral Church of Saint Louis, the hôtel de ville, public library, and museum. There is a considerable export trade in flowers, fruits, cork, and salt, the extensive salt marshes in the vicinity yielding over 20,000 tons annually. The neighborhood has the remains of a Roman town. In medieval times, as Hiedera, Hyères was a favored port of call for Oriental pilgrims, and as late as the fourteenth century was of greater importance than Toulon. Population, in 1901, 17,659.

HYGEIA, hi-ge'yà (Lat., from Gk. 'Tyícia, Hygieia, Υγεία, Hygeia, health, from ying, hygies, healthful; connected with Skt. ugra, mighty). In the ordinary tradition, the goddess of health, daughter of Asclepius, and honored with him at Athens, Epidaurus, Sicyon, Corinth, Titane, and elsewhere. She was joined with the god of healing, Amphiaraus, at Oropus, and on the Acropolis at Athens was an ancient cult of Athena Hygeia, to whom a statue and altar were erected after the great plague, and before the introduction of the worship of Asclepius in Athens. In the art of the fifth and fourth centuries B.C., Hygeia is represented as a maiden, but of the fully developed and vigorous type, while later her form is more youthful and girlish. She is represented in company with her father, or sometimes alone, with the snake by her side or drinking from the patera in her hand. Hygeia seems to be an originally independent divinity, but later came into connection with various deities who had become associated with the cure of disease.

HYGIENE, hiji-en (from Fr. hygiène, from Gk. vyiaíveiv, hygiainein, to be healthy, from vyths, hygies, healthy). The branch of medical science which deals with the preservation of health. Within its scope are all measures taken for the acquisition and preservation of health, except those involving purely medical and surgical means. Hygienic measures were a part of religious observance among the Jews, as well as among the people of Assyria and India, and their enforcement lay with the priests. Among

the Greeks these duties were transferred to the physicians. Hippocrates's work on Air, Water, and Places was largely responsible for this change. (See HIPPOCRATES.) In the twentysecond book of Homer's Odyssey there is an account of the sanitary precautions taken by Ulysses after the killing of the wooers. The place of slaughter was cleansed and disinfected by scraping and washing, and by burning sulphur. Little attention appears to have been paid to the infected individual in the olden time, when the panic ensuing upon a plague caused expulsion or expatriation of the sufferers. Laws were framed

to protect the public from lepers, for example, by expelling them and burning their houses. In 1423 Venice established its first lazaretto, and in 1485 a permanent health magistracy was created in that city. In 1532 an act of Parliament authorized in England the issue of commissions of sewers for "the overlooking of sea banks and sea walls, and the cleansing of rivers, public father was fined for throwing filth into the street, streams, and ditches." In 1552 Shakespeare's and again in 1558 for not keeping his gutter

clean.

Roman law provided no protection for the individual. Greek and Latin writers treated of diet and exercise for the patrons of literature, school of Salernum, about the twelfth century, for princes, and for the wealthy. From the issued the Code of Health, which was printed in

1480, and for two centuries thereafter remained the standard work on personal hygiene. Despite which were enacted by James I., and the establishthe stringent laws seeking to prevent plague ment of lazarettos into which ships discharged their cargoes for detention and airing, serious outbreaks of the dread disease occurred in 1625 and 1629-31. In 1665, according to Macaulay's estimate, the number of deaths from plague during one period of six months reached more than 100,000.

At the close of the eighteenth century little advance had been made in hygienic knowledge beyond the discovery by Woodhall, in 1617, that scurvy was prevented by the use of lemon-juice; the discovery by Morton, in 1697, that foul air produced disease in some way; and the introduction from China into England in 1717 of inoculation with smallpox virus by Lady Mary Wortley Montagu. Differentiation of fevers began early epidemic in London of 1831-32, newly awakened in the nineteenth century. Following the cholera interest resulted in the formation in 1838 of a system of registration of deaths in that city. The establishment of the fact of water-borne diseases was made by the investigations of Dr. John Snow into the cholera outbreak in London, in 1848-49. From this date investigation has been systematically pursued into the causes of death; the causes of disease, its spread, and the agencies that produce it; and into the conditions that promote health. The use of the microscope, the study of bacteriology, of pathology, of the chemistry of food, of climate, and of exercise have all added to the knowledge that has increased the useful application of hygienic principles in our day. Sanitary laws have been enacted which control unhealthful agencies and aim to safeguard and regulate commercial as well

as domestic relations.

to its relations, and the objects in view. There Hygiene may be variously classified, according is the hygiene of the individual, of the family, and of the municipality or State; which may be denominated personal, domestic, and public hygiene.

PERSONAL HYGIENE. This includes the study of (1) Food, including water and beverages. Food should be adapted to the season of the year, the age, occupation, and the condition of health of the individual. An increase in the quantity of fruit and of water, a greater proportion of vegetables, and smaller meals are desirable in hot weather, while an increase in meat and in cereals

DOMESTIC HYGIENE. This includes the study of (1) The Management of Infancy, (2) Preparation of Food, with regulation of meals, as well as supervision of cooking, and (3) the Hygiene of the Sick-Room, including removal of dust-catching furnishings, regulation of heat, light, and ventilation, provision of utensils which may be sterilized, care of bedding and bed-linen, and arrangements for proper bathing and nursing. Besides these subdivisions, others might be made which would duplicate some of the titles more properly assigned to personal or public hygiene; such as air, and hygiene of the school.

is desirable in cold weather. Infants require principally milk, with the proportions of proteids, fats, and sugar graded according to age and digestive capacity. Older children require small quantities of meats, cereals, fruits, and vegetables. In regard to occupation, it may be said in general that active laboring men, like carpenters, wheelwrights, and farmers, may partake of food which takes a considerable time to digest, with more advantage than sedentary men may. Pork and corn-cake or bread is a nutritious and sustaining diet to an active laborer, but should not form the habitual diet of a sedentary person. (See DIET, paragraph Diet in Disease; PUBLIC HYGIENE. This comprises care of the see also FOOD.) The investigation of water-sup- surroundings of man, as well as prevention of ply, examination for noxious ingredients or me- disease, and disposal of the dead; and therefore dicinal properties in drinking-water, as well as includes a consideration of: (1) Climate, as one directions for its use, come within the province of of the agencies active in man's environment, is hygiene, as does also the use of coffee and tea, used as an elastic term to embrace the range of which are both stimulating drugs, causing in temperature of a locality, the prevailing winds, some persons overaction of the heart, cerebral ac- the rainfall, the vegetation, and the soil. (2) tivity resulting in insomnia, and indigestion; of the Soil under Dwellings, with reference to poscocoa, which is slightly stimulating, but contains sibilities of drainage-proximity to underground food; of wine, beer, and distilled liquors, all of water, etc. (3) The Character of Dwellings, which are drugs in the eyes of the physician especially tenements, as to ventilation, and airand the sanitarian, to be used with accurate cal- space, position, and materials used in construcculation of their nutrient and stimulant prop- tion, and provision for regulating temperature, erties. (See ALCOHOL, PHYSIOLOGICAL AND POI- water-supply and drainage. (4) Cleansing of SONOUS ACTION OF.) (2) Clothing should be suited Dwellings and Disposal of Refuse. (5) Cleansto the temperature, age, and occupation. Venti- ing of Streets in towns. One of the most imporlation as well as materials-wool, cotton, linen, tant questions of public hygiene is the cleaning and silk-must be considered. (3) Work and of streets, and matters connected therewith. Exercise are necessary for every one. Regular Filthy streets are productive of disease not only physical activity is essential to proper devel- by the generation of poisonous gases, but also opment, and to the maintenance of normal the dust which results from the long-continued action of the vital organs, and the repair of trituration of excrementitious and decaying subtissue. Even those who are confined to bed stances is extremely injurious to the mucous by disease need exercise, which is secured by membrane of the air-passages, and productive of passive motion or massage. (See GYMNAS- contamination to blood and tissue. The habit of TICS; EXERCISE; MASSAGE.) To work must casting the sweepings of houses and stores upon be joined the consideration of rest and sleep, the sidewalks, especially during the hours in which should be enjoyed at regular intervals, which pedestrians are passing, is a greater evil and in quantities proportioned to individual than many suppose. The dust of these places is conditions and occupations. (See SLEEP.) (4) often of the most objectionable character, conPersonal Cleanliness includes regular evacua- taining the germs of contagion, and there is no tions of the bowels daily; daily bathing, securing doubt that many 'filth diseases' (q.v.) are propaconstant removal of perspiration; care of the gated in this manner. (6) Regulation of Public hair and scalp, and care of the nostrils, of the Conveyances. Public conveyances are frequent cavity of the mouth and teeth, of the genitals, causes of disease from various sources. The dust and of the anal orifice. (5) Special Habits which is allowed to collect in street cars, and also ordinary steam railway cars, is of itself a frequent cause of diseases of the air-passages; but compared to the evils which result from overcrowding and bad ventilation, it is of minor importance. Pneumonia, pleurisy, bronchitis, and laryngitis are frequent results of street-car exposure. But one of their greatest evils, and one not yet sufficiently recognized by the public, is the want of attention paid to the smoothness although well known to the medical profession, of the track and the springs of the cars. street cars undue jarring should not be permitted. When they are properly supplied with springs, and when wheels that are flattened are be avoided. (7) Control of Air-spaces in Public promptly replaced, all injurious vibrations will Buildings, such as hospitals, asylums, orphanages, lecture-rooms, theatres, school-houses, etc. The vitiation of air due to impurities added to it by respiration is a subject of great moment. Following are figures showing the difference in the proportion of the constituents of the percentages of expired air and of ordinary air:

which tend to undermine health should be controlled; the use of tobacco, of other narcotics, and of stimulants should receive consideration. Tobacco should never be used before the age of twenty-one or twenty-two years has been reached, and should rarely be used by neurasthenics. In certain diseases, as Bright's disease and syphilis, and certain conditions of the heart, tobacco is

pernicious. All other narcotics are distinctly deleterious, and should be forbidden. (6) Control of Sexual and Other Passions has much to do with personal health. Indulgence in masturbation by the young delays development, and in a vast majority of cases causes mental enfeeblement. Excessive sexual intercourse has a similar effect, with greater disaster to the male. Per haps the most undermining of normal mental activities are anger and grief, and these should be avoided or limited. The thoughts should be calm, and mental exercise, as well as physical, should be regularly taken. Mental indolence leads more often to mental disorder than does

mental overwork.

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From these figures it is seen that expired air contains over one hundred times more carbon dioxide and nearly 5 per cent. less oxygen than ordinary atmospheric air. Experiments have shown that the average adult emits with each expiration 22 cubic inches of air; or, assuming 18 respirations a minute, 570,240 cubic inches or 330 cubic feet of air in 24 hours. In this total of expired air there is 14.52 cubic feet of carbon dioxide. This amount is increased with increase of physical activity. The figures of De Chaumont, which are generally accepted, show that there is 0.6 part of carbon dioxide per 1000 in the air of a closed and occupied space, or 0.2 part in excess of that in ordinary atmosphere. Burning of coal or illuminating gas adds to the impurity, and hence ventilation is essential. In public buildings, such as those named, there should be three cubic feet of space per person in each room, after deducting from the total room-space the amount occupied by furniture and the bodies of the persons. (8) Prevention of Disease. This is a very large topic, and necessarily bears close relation with personal as well as domestic hygiene. It includes notification of diseases to a health officer; most of the activities of municipal departments of health (see HEALTH, BOARDS OF); control of streets and houses, and disposal of refuse (see DISINFECTANTS); control of disease entering our ports (see QUARANTINE); prophylaxis of special kinds against spread of disease (see ANTITOXIN; SERUM THERAPY; VACCINATION); cleansing of public vehicles, to which reference has been made, etc. Overcrowded and dark tenements are the most frequent causes of the spread of disease in a community. They keep alive the diseases of childhood-measles, scarlet fever, diphtheria, etc.--and are the most frequent hiding-places for the germs of tuberculosis. Disposal of the Dead is regulated by sanitary laws, which provide, in cities, that undertakers shall obtain permits for removal of dead bodies, and proper disposition shall be made of them by burial or cremation. Public funerals in the case of contagious diseases are often forbidden, and hermetically sealed caskets are enjoined in such cases by many municipalities.

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MENTAL AND PHYSICAL HYGIENE. To regard the matter from another view-point, hygiene may be also divided into mental and physical. The former will necessarily include many questions that belong to the latter, for the healthy action of the mind depends to a great extent upon the health of the body. A sufficient amount of sleep ought to be taken to refresh the powers of the mind, as well as those of the body, and that sleep ought not to be much disturbed by dreams. Of course there are those whose occupation demands varied, sometimes excessive exertion, and who must be 'a law unto themselves.' The great time for practically applying the laws of mental hygiene is during the years of childhood and youth. The method of teaching the child should be of the simplest, as well as of the most comprehensive character, and the periods should be frequent during which its mind is completely relieved of all serious study, and allowed to come

to a perfectly natural and passive condition by mirthful and affectionate enjoyment. The schoolrooms should be commodious, and well ventilated, and they should not be overcrowded. Too many studies should not be required, so that hours which should be given to recreation or sleep will not be occupied with laborious efforts of study, which often do little more than produce a disturbed and unrefreshing sleep, and pervert or destroy the appetite for wholesome food. In the matter of school hygiene, great importance is attached to the amount, arrangement, and distribution of light in the class-rooms; the construction of the seats and desks; the type and paper used in making the text-books, etc. Carelessness in these matters is known to be one of the most fruitful sources of imperfect sight, such as myopia, as well as of various deformities, especially spinal curvature.

MILITARY HYGIENE. This term is applied to the sanitary care of the soldier in camp and garrison, and while on the field. Military hygiene embraces a consideration of: (1) The Selection of the Recruit, his exercise and training, his general development, and his mental and moral education. (2) The March in Campaign; the work done on the march, the equipment, rests, use of fluids, mental occupation, accidents, strain, and the general health of the troops. (See MARCHING.) (3) Water for Drinking, its purification and protection. (See ENCAMPMENT.) (4) The Ration: its choice, amount, and variety; cooking of meals, disease as related to food, emergency or reserve ration, and travel ration. (See RATION.) (5) Military Clothing and Equipment (see UNIFORM, MILITARY); head-covering, underclothing, disposition of the equipment. (6) Camp Sites, and Camps, with attention to soil, vegetation, shelter, and area, and their sanitary administration. (See ENCAMPMENT.) (7) Posts, Barracks, and Hospitals. (See HOSPITALS, par. Military.) (8) Ventilation, Heating, and Lighting. (9) Disposal of Excreta and Waste. (10) Personal Cleanliness of the Soldier. (1) The Soldier's Diseases and Mortality. (12) Disinfection. (13) The Habits of the Soldier as Affecting His Efficiency. (14) Climate, and Life on a Troop-Ship. (15) Disposal of the Dead.

BIBLIOGRAPHY. Willoughby, Hygiene for Students (New York, 1901); Harrington, Practical Hygiene (New York, 1901); Sedgwick, Sanitary Science, and the Public Health (New York, 1902); Hamer, Manual of Hygiene (London, 1902); Munson, The Theory and Practice of Military Hygiene (New York, 1901). See SANITARY SCIENCE; TUBERCULOSIS; HEATING AND VENTILATION.

HYGIENE OF FOOD. See FOOD.

HYGI’NUS, GAIUS JULIUS. A Latin author. He is generally supposed to have been a native of Spain, though some writers claim that he was born in Alexandria, Egypt, and that he came to Rome with Julius Cæsar when a mere child. He is known to have been a favorite with Augustus, who made him chief librarian in the new Palatine Library. He was a voluminous writer on many subjects, including biography, agriculture, bee-keeping, and military arts, as well as comments on the poems of Vergil and Cinna. These have all been lost. There are also two works still in existence that are assigned to him, one, a textbook on mythology, entitled Fabularum Liber,

consisting of 277 mythological legends, valuable chiefly because of the use made of the Greek tragedies; the other, an astronomical treatise entitled Poeticon Astronomicon Libri IV., of little value now. The Fabula are edited by Schmidt (Jena, 1872), and the Astronomica by Bunte (Leipzig, 1875). Another Hyginus, known as Gromaticus, lived probably in the second century, and wrote a work on surveying; edited by Gemoll (Leipzig, 1879).

HYGINUS, SAINT. Pope, or Bishop of Rome, about the middle of the second century, possibly 137-141. Very little is known about him.

HYGROMETER (from Gk. vypós, hygros, moistμέrpov, metron, measure). An instrument for measuring the quantity of moisture in the atmosphere. In addition to the gases of which it is composed, the air contains the vapor of water, which is invisible except when it is condensed in the form of fog or cloud. The amount of this aqueous vapor varies greatly, and depends chiefly on the temperature, being at a minimum on cold days, and on warm days forming as much as one-fiftieth part of the air. This vapor has a certain tension or pressure depending upon the temperature, and when the latter is sufficiently reduced condensation takes place and dew is formed. The temperature at which the air contains a maximum of moisture for a given pressure is called the temperature of saturation for that pressure, and if the temperature is reduced below this point condensation takes place. The temperature at which condensation occurs is known as the dew-point (see DEW) temperature. The less moisture the air contains the lower will be the dew-point, and when this is ascertained experimentally, we can use it to determine the pressure of the vapor at that temperature, as the pressure of water-vapor and its relation to temperature has formed the subject of extensive and elaborate experimental researches that are now embodied in carefully prepared tables. It is known that the quantity of water contained in the air varies directly (or nearly) as the vapor pressure, consequently a ratio between the vapor pressures at an observed temperature, and at the temperature of condensation for the atmospheric condition at the time of observation, would give the relative humidity. It is in terms of relative humidity that the amount of moisture in the atmosphere is expressed in the daily weather reports, and the chief function of the hygrometer is to afford such data as will enable us to determine this quantity.

Hygrometers can be divided into several classes. There are those in which use is made of the property of certain substances of altering their dimensions or weight upon absorbing moisture from the air. Of this class the most used are those in which a hair expands and contracts according as the air is more or less moist, and moves a pointer or index over a scale, and indicates relative humidity direct. This form was invented by Saussure, the Swiss physicist, and a somewhat similar instrument was devised by Deluc in which a strip of whalebone was employed. The instruments are known as hygroscopes, and may be used indoors or where only an approximate reading is desired. Another class of hygrometers is based on the principle that certain chemicals will absorb moisture, and the amount thus abstracted from a given volume

of air will give the quantity present in the atmosphere. The apparatus consists of a series of drying-tubes containing some hygroscopic material, as substances which readily absorb moisture are termed, through which air is forced by means of an aspirator or other device. The substances which may be used for this purpose are strong sulphuric acid in pumice-stone, calcium chloride, phosphoric acid, and potassium or sodium oxide. The amount of moisture is determined by the increase in weight. The class most where the temperature is reduced until congenerally used, however, includes apparatus densation takes place, or this temperature can be determined from the temperature of evaporation. Knowing the dew-point for a given condition of the atmosphere, the other data can be readily ascertained.

The Daniell hygrometer, which figures extensively in the earlier works on physics and meteorology, consists of two bulbs connected by a bent tube, as represented in the figure, and inclosing a thermometer together with some ether, and vapor of ether, the air having been expelled before the tube was sealed. One bulb is either blackened or coated with metal, while the other is covered with muslin. The observer's hand is placed for a short time on the muslincovered bulb to drive the ether into the

DANIELL HYGROMETER.

a fresh

opposite bulb, leav ing the first bulb and the tube filled with the vapor of ether. A little ether is then dropped from the bottle on the muslin-covered bulb; evaporation instantly takes place, and the temperature is reduced, thus condensing the vapor inside; evaporation from the other bulb fills the vacuum, and the vapor is again condensed by dropping more ether on the muslin covering, the process being repeated until the temperature of the bulb containing the thermometer is so reduced by successive evaporations (see EVAPORATION) that dew begins to be formed on the outside of the bulb. At the instant this occurs, the height of the mercury in the two thermometers is accurately noted, the one giving the dew-point temperature, and the other the temperature of the air. There are other forms of dew-point apparatus, all depending upon this same principle, and the hygrometer of Regnault was devised to remedy some of the defects of the Daniell apparatus. In this instrument a current of air is used to increase the evaporation of the ether, and instead of a glass tube and bulb there is a brightly polished thimble of silver at the base of one of the thermometers, which contains the ether. The air bubbles through the liquid, and the rate of evaporation becomes much more rapid. Knowing the dew-point, a reference to the table will furnish the pressure of aqueous vapor at that temperature, and other tables or the appli

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