Hygiene may be variously classified, according to its relations, and the objects in view. Tere 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 has little to consider beyond questions of diet, cleanliness of person, habits of thought and study, and of morals and locality of residence. Domestic hygiene regards the condition of the whole household, the apportionment of sleeping apartments to different members, the general regulation of meals and the preparation of food, and is brought into more immediate relations with public hygiene, as the householder will often need to have intercourse with the public authorities. Public hygiene has the con sideration of measures for the laying cut of a city, for the disposal of its refuse, for the supply of water, and the occasional enforcement of quarantine regulations. In a more enlightened sense it must also have regard for the education of the inhabitants in such a manner as will dispose them to cleanly and thrifty habits. 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. It is a matter of common ex, perience that retiring at night with too full a stomach—and with some persons with any food in the stomach—is provocative of disturbing dreams. The thoughts should be calm, and mental exercise, as well as physical, should be regularly taken. Of course there are those whose occupation demands varied, sometimes excessive exertions, and who must be "a law unto themselves." No rules of mental hygiene are possible with them, except that they shall keep the blade of the intellect. as keen and as bright as possible by a fair diet, what exercise they can find time to enjoy, and be always ready for an intellectual encounter. There are lawyers and other professional men, journalists, physicians, and a few public officers whose duties are so thoroughly wound up in the progress and success of causes and enterprises, in questions of life and death, and the loss or the rescuing of fortunes, that there is scarcely such a word as rest with any practical import to them. But the great time for practically applying the laws of mental hygiene is during the years of childhood and youth, before the struggles of life commence. The method of teaching the child should be of the simplest as well as of the most com prehensive character, and the periods should be frequent during which its mind is completely taken away from all serious study, and allowed to come to a. perfectly natural and passive condition by mirthful and affectionate enjoyment. Let the schoolrooms to which youth are sent be commodious and well ventilated, and after these advantages are secured let them not be thrown away by overcrowding. It is questionable whether the bringing together of over one thousand, or even that number, of children in one building, even though a large one, is not in violation of sanitary principles. Too many studies should not be required, so that hours which should be given to recreation or sleep will not be occupied, as is now too often the case, 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. As to moral hygiene, which is a part of mental, it is nefksisary te, say only that tbe•striet thOse, laws which are inculcated by Christianity and sought to be enforced by the civil authorities of all enlightened nations, will be conducive not only to soundness of the whole mind, but also to soundness of the whole body.
Physical hygiene preaents itself in various aspects, embracing exercise, diet, occupation, etc. Exercise is cii important element of hygiene. See EXERCISE, GYMNASTICS, ante. For the hygiene of diet, see DIET, ante. By the hygiene of occupation or employment is meant the hygienic influence of different employments upon the individual. It is evident that the occupation of a lawyer or journalist or physician has vastly different hygienic rela tions from that of a shoemaker or carpenter. It is evident that a carpenter will need but little more exercise than is given him by his occupation; but his diet, and his time and manner of sleeping, and his habits of cleanliness and bathing, will have consider able importance. It is hardly necessary to say that he should have a generous diet, should occupy an airy and well-ventilated chamber for sleeping, and that his food should usually be different from that of the shoemaker, lawyer, or doctor, 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 can. 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. But the influence which the occupation of a person may have upon his health is a hygienkquestion which can only be hinted at in a brief treatise. The rules of hygiene are subject to change according to circumstances. That which is beneficial to one person is often injurious to another, and nothing but the' application of the broadest common sense in the most catholic spirit can he expected to apply to questions as to what any person ought to eat, to drink, or as to how many miles he or she ought to walk every day. In conclusion, it may be remarked of public hygiene that it can only be regulated by the enforcement of sanitary laws; and that to be efficient, especially in cities, they need to have reference to many things. One of the most important ques tions of public hygiene is the cleaning of streets and matters connected therewith. Filthy streets are productive of disease not only by the generation of poisonous gases, but also the dust which results from the long-continued trituration of excrementitious and decaying substances is extremely injurious to the mucous membrane of the air passages, and productive bf contamination to blood and tissue. The habit of casting time sweep ings of houses and stores, upon the sidewalks, especially during the hours in which pedestrians are passing, which is so prevalent in most of our cities, is a greater evil than many suppose. The dust of these places is often of the most objectionable character. containing the germs of contagion, and there is no doubt that many filthy diseases are propagated in this manner. It is impossible to see how such abuses can be remedied, except by municipal regulation.
Public conveyances are frequent causes of disease from various sources. The dust 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. The over crowding which is deliberately practiced on some of the street railroads, coupled with the draughts of cold air from windows opened regardless of comfort, is undoubtedly a considerable factor in the death-rate of our large cities. Pneumonia, pleurisy, bron chitis, and laryngitis are frequent results of street-car exposure. But one of their greatest evils, and one not yet sufficiently recognized by the public, although well known to the medical profession, is the want of attention paid to the smoothness of the track and the springs of the cars. This is commonly regarded as a matter of comfort, but this is its least important aspect. There is a disease recognized in legal medicine called railroad disease. It is a nervous affection, caused by the continuous vibration of the cars. This vibration cannot he entirely avoided on rapid trains, but on some roads is so nearly so that little mischief probably results from this cause. On street cars undue jarring should not be permitted. When they are properly supplied with springs, and the seats cushioned, all injurious vibrations will be avoided, even when the track is not perfectly smooth. A delicate lady is often seriously injured by riding in a car on a bare wooden seat, without a cushion to relieve the jar resulting from the imperfect springs, and physicians are constantly meeting with patients whose diseases are directly traceable to this cause. Several years ago, when the street cars, which were then cushioned, became so filthy as to be known agents of contamination, the abandonment of cushions was popularly hailed as a relief. It was, however, only a partial relief, front filthiness; it has been injurious in another direction, but there is no reason why the seats of all public conveyances, which are paid, as a rule, in proportion to the amount of wear entailed by travel, cannot be comfortably cushioned and kept clean. Hygiene has its thousand relations to all the habits and conditions of life, and although many of them lie within the limits of private life and cannot be subjected to legal interference, gross violations of sanitary laws ought not to be permitted in public estab lishments. See WARMING AND VENTILATION.