566 H Y G H Y G Giens, which juts due south into the Mediterranean, where salt is made by the exposure of the sea-water to the sun. Up to the 14th century Hyeres was a larger and more im portant town than Toulon; and in the 16th century it became famous as a winter resort. Catherine de Medici at one time thought of making it the seat of a royal residence. At present the more brilliant social attractions of some of the neighbouring watering-places of the Riviera divert the more fashionable visitors from Hyeres. In climate it differs little from its more favoured compeers. From the east and north-east winds it is completely sheltered, but it lies open to the ravages of the mistral. The population in 1872 was returned at 5881 for the town and 11,21-2 for the commune; in 1876 the corresponding figures were 6797 and 12,289. The islands of Hyeres (the Stoechades at ^roixaSes 1/770-01 of the classical geographers), other wise called Les lies d Or, lie to the east of the peninsula of Giens, and form a protection to the roads of Hyeres, one of the great rendezvous of the French fleets. The principal islands are Porquerolles, which rises to a height of 600 feet, Port-cros, and Titan. The population is scanty. A marquisate of the lies d Or was created by Francis I. See Alphonse Denis, Promenades pittoresques A Hy&res, 1842; Eugene Farenc, Les ricits du touriste Provencal, 1859 ; Aufauvre, Hyeres et sa valUe, 1862; Joanne, Hyeres ct Toulon, 1870; Len- theric, La Provence maritime, 1880. HYGIENE is the science, PRACTICAL HYGIENE the art, of preserving health. The name has been adopted from the French, from which language it has also been introduced into most other tongues ; it is derived from the Greek vyteia or iiyeia, health. Writings on health are among the oldest in the world, for the subject has engaged the attention of the profoundest thinkers and the most renowned leaders of men. We have only to point to the elaborate directions in the Mosaic laws for the preservation of health through scrupulous attention to cleanliness, the isolation of the sick, and extreme care in the use of wholesome articles of food and drink. Throughout the whole of their history the Jews enjoyed a remarkable immunity from epidemic disease, the most of the instances in which such disease occurred being represented as those in which they departed from the law and doubtless relaxed the wholesome vigilance enjoined by it. In mediaeval and modern history they have often, even down to our own time, been spared the ravages of epidemics, when their Christian neighbours were perishing around them. Ignorant superstition often gave rise to the idea that they had poisoned the wells, and they fell victims to the fanaticism of the times. It is highly probable that the periodical cleansing of their dwellings, involved in the thorough search for the leaven which preceded the yearly passover (Mishna, Pesachim, i. 11), had a notable influence in preventing that continuous deposition of organic matter, which is no doubt one most powerful factor in the production of zymotic disease. On the other hand, the filthy habits of the Christian populations offered a premium to plagues of every kind ; for there is no parallel in ancient history to the terrible invasions of disease which from time to time ravaged Europe down to quite recent times. It is the province of hygiene to seek out and determine the causes of disease, and to formulate rules for their prevention and removal. It may thus be called also preventive medicine, although this term does not quite express all that must be included. The progress of hygiene, such as it was, rested for many ages upon an empirical basis, and indeed to a large extent this is still the case. The subject has, however, in later times at least, been studied to considerable advantage, although much remains to be done. Two centuries ago the mortality of London was 80 per 1000 at the present day it is under 23. A century ago ships could barely keep the sea for scurvy, whilst jails and hospitals were in many cases the hotbeds of fatal disease ; now those conditions are rectified, or at least the means of rectifying them are known. Thirty years ago the English troops at home died at the rate of 20 per 1000 now their death-rate is less than one-half of this. A know ledge of the causes and modes of propagation of disease being necessary in order to provide rules for its prevention, it is obvious that hygiene must be largely dependent upon the advances made in pathology and aetiology ; hence the impossibility of any very marked progress in former times, by reason of the imperfection of the collateral sciences, and the want of the appliances more recently made available for inquiries of such a difficult and recondite character. Within this century, however, and especially within the last forty or fifty years, it has been possible to follow out the subject on a more strictly scientific basis, and so to lay a foundation, at least, on which to build a structure, which may one day entitle hygiene to a place among the more exact sciences. The special subjects which hygiene embraces are the fol lowing: I. Those which concern the surroundings of man; such as meteorological conditions, roughly included under the head of climate ; the site or soil on which his dwelling is placed ; the character, materials, and arrangement of his dwelling ; the air he breathes ; the cleansing of his dwell ing, and the arrangements for the removal therefrom of excreta and other effete matters. II. Those which concern the personal care of health ; such as the food he eats and the water and other beverages he drinks; clothing; work and exercise; personal cleanliness; special habits, such as the use of tobacco, narcotics, &c. ; control of sexual and other passions. III. Certain points not directly included in the above ; such as the management of infancy ; the prevention of disease; the hygiene of the sick-chamber; and the disposal of the dead. It is obvious that it is impossible to draw any hard and fast line in these divisions, and that they must constantly run into and overlap each other, Such a division, however, gives a general idea of the scope of the science, and a brief consideration of the different sections will enable us to furnish a slight sketch of the nature of the subject. 1. Meteorological or (so-called) climatic conditions. Here temperature and humidity are the two points that obviously present themselves for consideration, but it is very difficult indeed to separate their influence from those of soil or site. It is also certain that much that has been attributed to climate is really due to other causes. It may be laid down as a general principle that, if moderate care be taken, man may preserve his health in almost any part of the world, although it must be admitted that in some places, such as hot and moist climates, disease causes appear to be more easily called into action than under colder or drier conditions. Some diseases, such as yellow fever, appear to require a certain temperature for their development and propagation ; others, such as enteric (commonly called "typhoid") fever, appear to exist indiscriminately under any meteorological conditions ; others, such as cholera, although undoubtedly originating in hot and moist countries, appear capable of being propagated in most parts of the world. In some cases great heat and dry ness arrest disease, as used to be observed in Egypt, where the plague was commonly said to cease after St John s day. During the hot harmattan wind of the west coast of Africa small-pox is arrested, and successful vaccination becomes impossible. To the sick or delicate, meteorological conditions are of great importance, but this part of the subject belongs more to the treatment of disease than to general hygiene. To the healthy, meteorological conditions, however much they may affect
personal comfort, are of comparatively little moment as
