these factors are the nature of the water-supply and the character of the drainage. The relation of these factors to the public health will be considered in detail in special chapters. Dampness of the soil of a locality is also an important factor, and its influence in relation to consumption has been carefully investigated by Dr. Bowditch, of Boston, and Dr. Buchanan, of London. Their

1 Hospital and Almshouse.

investigations have shown that the death-rate from consumption is in proportion to the dampness of the soil. Dampness of soil is also an important predisposing factor in the production of many other diseases, such as malaria, rheumatism, and catarrhal affections.

The influence of the nature of the occupation, and of the climate of a locality, as predisposing factors of disease will be discussed in detail in special chapters on these subjects.

Sanitary science refers to the investigation of the causes of disease and the means of avoiding or destroying them. It is not a specific department or separate branch of science, but is implied, in part, in a number of sciences, as chemistry, biology, physics, pathology, statistics, etc.

The term sanitary means conducive to the preservation of, and the term sanitory conducive to the restoration of, health. The sanitary condition of a place has reference to the presence or absence of the specific causes of disease. There is no such thing as bad hygiene: A place is either in hygienic condition or it is in an unhealthful condition.

Hygiene aims to discover the causes of all diseases known, and the best means of removing those causes or rendering them inoperative. It takes for granted a knowledge of the normal functions of the human organism, and seeks to discover the reasons for perverted action of a part or the whole of the organism. It involves a thorough knowledge of the normal conditions of man's environment as well as the various factors which tend to render that environment abnormal. It demands a thorough knowledge of the chemical and physical character of man's food-supply and those changes to which it is liable that tend to injure his health and produce disease. It aims to keep persons in perfect health, to train men to be strong both mentally and physically. It also involves a knowledge of the physical and geological nature of the surface of the earth, and the manner in which these conditions, in different localities, influence the healthfulness

of human habitations. It comprises a knowledge of all the various human ocupations, and the manner in which these may be conducted so as to be free from danger to health or how to render them least objectionable.

Hygiene may be subdivided into several departments relating to the scope of its application, as public or general, military, naval, personal, municipal, school, and industrial hygiene. Public hygiene takes cognizance of factors which affect the general public, such as nuisances of different kinds: Foul odors, noxious gases or dust evolved in certain manufacturing processes, and loud noises. Nuisances are generally such conditions which aggravate existing disease rather than produce disease. Military, naval, personal, school, and industrial hygiene will be treated more or less generally in special chapters. Municipal hygiene has reference to those conditions which affect the general health of a community that fall directly under the control of municipal governments, such as the influence of impure water-supplies and imperfect drainage upon the general health; the influence of overcrowding in the habitations of the poor; the cleansing of city streets and the removal and satisfactory disposal of refuse matters; the regulation of the isolation and care of those affected with infectious diseases, and the proper disposal of the dead.

Sir

Development of Hygiene.-Modern hygiene has been gradually evolved out of the observations and discoveries. of many men prominent in philanthropic work, in medicine, and in science. Among the prominent observations and discoveries made during the eighteenth century which have been most instrumental in the development of hygiene may be mentioned the discovery of George Baker with regard to the production of leadpoisoning by cider stored in leaden vessels; the observations of John Howard with regard to the baneful influence of foul air and overcrowding and unhealthfulness of the surroundings upon the health of the occupants of prisons, poor-houses, and other habitations, and their relation to

typhus fever; the demonstration by Captain James Cook, in his voyage around the world, that scurvy was a preventable disease which was due to the nature of the diet; and Sir Edward Jenner's discovery of inoculation as a preventative of small-pox. During the nineteenth century the movements and discoveries which stand out most prominently are the work of Dr. Thomas Southwood Smith and The Sanitary Committee in demonstrating the factors which are instrumental in influencing the health of towns, such as the accumulation of filth about premises, absence of sewers, and consequently the pollution of water-supplies, and the influence of insufficient air-supply and overcrowding upon the general health; the labors of Edwin Chadwick in organizing the first board of health in England; the work of Dr. William Farr, Registrar-General of England, in securing the registration of the cause of death in the health reports; the labors of Dr. E. A. Parkes in demonstrating the evil effects of defective drainage and the accumulation of filth upon the public health, and in securing the passage of various sanitary acts from 1848 to 1857; the work of Dr. John Simon, of London, and his able staff of medical inspectors with regard to the material causes of disease, and the legislation which was based upon these investigations; the studies of Dr. C. A. Louis, of Paris, upon typhoid, typhus, and relapsing fevers, and the differentiation between these, as well as similar studies made at the same time by Dr. William W. Gerhard, of Philadelphia; the studies of Dr. Henry I. Bowditch, of Boston, and those of Dr. George Buchanan, of London, upon the influence of dampness of the soil upon the prevalence of consumption; the studies of Louis Pasteur upon the causes of fermentation and the etiologic relation of micro-organisms to disease, as well as his discoveries with regard to the prevention. and treatment of these diseases; the studies of Sir Joseph Lister with regard to the prevention of suppuration in wounds, which have been the starting-point of modern antiseptic and aseptic surgery; the work of von Petten

kofer in introducing new methods of chemical research upon air, water, and food, and his studies upon the influence of soil-moisture upon the prevalence of typhoid fever and cholera; and the discoveries of Dr. Robert Koch, of Berlin, of the specific micro-organisms of some of the infectious diseases, and in perfecting methods of bacteriologic research.