Page:Popular Science Monthly Volume 58.djvu/180

172

HE laboratory idea is fast taking hold of our municipalities. It is the natural result of modern science and American practicality. More and more our civilization is making use of the great forces of nature, and more and more is it becoming necessary that nature's laws should be understood: hence the need for the precise data of the expert and the long-continued observations of the specialist. This is emphatically true in the domain of sanitary science, where the advances in chemistry, microscopy and bacteriology have wrought revolutionary changes. The microscope is no longer a toy, it is a tool; the microscopic world is no longer a world apart, it is vitally connected with our own. The acceptance of the germ-theory of disease has placed new responsibilities upon health authorities and has at the same time indicated the measures necessary to be taken for the protection of the public health. With the knowledge that certain diseases are caused by living organisms find that these may be transmitted by drinking-water has come the need of careful supervision of public water supplies, which has resulted in the establishment of many laboratories devoted to water analysis.

The pioneer work of the Massachusetts State Board of Health and the Board of Health of New York City has been followed by the installation of laboratories in most of our large cities. In many cases these are operated in connection with departments of health, and the supervision exercised over the water supplies is of great benefit to the communities. An instance of this is furnished by the Health Department of Chicago. The water supply of Chicago is taken from Lake Michigan, and before the operation of the drainage canal the sewage of the entire city was discharged into the lake. The location of the water-works intakes was such that the water pumped to the city was subject to great changes in quality, varying from day to day according to the direction of wind and currents. For a long time it has been the practice of the department to issue daily bulletins as to the sanitary condition of the water in the city. Samples from the various sources of supply are received at the laboratory each morning, and upon the results of certain rapid methods of analysis the chemist bases his judgment as to the probable character of the water in the city mains during that day. The report is promptly given to the representatives of the press, and the consumers are thus warned of approaching danger.