Perin' 11Y1,11:NE. This comprises care of the surroundings of man, as well as prevention of disease, and disposal of the dead: and therefore includes a consideration of: ( I ) Climate, as one of the agencies active in matit's environment, is used as an elastic term to embrace the range of temperature of a locality, the prevailing the rainfall, the vegetation, and the soil. (2) the Sol/ tole r Direllinos, with reference to pos sibilities of drainage-proximity to underground water, etc. (3) 'Ile ('harmder of Da., !linos, especially tenements, as to ventilation, and air space, position. and materials used in construe lion. and provision for regulating temperature, water-supply and drainage. (4) eira rising of Dire/lbws and Disposal of Refuse. (5) Cleans. ing of Streets in tov.ns. One of the most impor tant questions 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 deeaying sub stances is extremely injurious to the mucous membrane of the air-passages, and productive of contamination to blood and tissue. The habit of casting the sweepings of houses and stores upon the sidewalks. especially during the hours in which pedestrians are passing, is a greater evil than many suppose. The dust of these places is often of the most objectionable character, con taining the germs of contagion, and there is no doubt that many 'filth diseases' (q.v.) are propa gated in this manner. (ti) Reputation of Public C'onreyanees. Public conveyances are frequent. eauses of disease from various soarers. The dust which is allowed to collect in street ears, and also ordinary steam railway ears, is of a frequent Pause of diseases of the air-passages; but compared to the evils which result from overerowding and lead ventilation. it is of minor importance. Pneumonia, pleurisy, bronchitis. and laryngitis are frequent results of street-ear exposure. But one of their greatest evils, and one not yet sufficiently reeog,nized 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 ears. On street cars undue jarring should not he per mitted. \\Then they are properly supplied with springs, and when wheels that are flattened are promptly replaced. all injurious vibrations will be avoided. (7) Control of ,t ir-spares in Public Buildings, such as hospitals. asylums. orphan
ages, leeture-rooms, theatres, school-houses, etc. The vitiation of air due to impurities added to it by respiration is a subject of great moment. Fol lowing are figures showing the difference in the proportion of the constituents of the percentages of expired air and of ordinary air: 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 IS respirations a minute, 570,240 cubic inches or 330 cubic feet of air in 24 hours. In this total of expired air there is 13.52 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 build ings, 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 per sons. (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 offi cer; most of the activities of municipal depart ments of health (see HEALTH. BOARDS OF) ; con trol 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 .:1NTITOXIN ; SERUM THERAPY; VACCINATION ) ; cleansing of public vehicles, to which reference has been made, etc. Overcrowded and dark tene ments are the most frequent causes of the spread of disease in a community. They keep alive the diseases of childhood—measles, scarlet fever, diphtheria, cle.—and are the most frequent hid Mg-places for the germs of tuberculosis. (9) 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 gaskets are enjoined in such cases by many municipalities.