It is, however, in the city of Lawrence that the most striking insight is obtained as to the manner in which typhoid fever may be controlled by conditions surrounding the water-supply to the community. Thus, whereas the death-rate from typhoid fever reached a mean of 11·2 per 10,000 in 1886-90, it fell to 7·7 in 1891-95 and to 2·5 in 1896-99. It was in the autumn of the year 1893 that the raw river-water supplied to the city from the Merrimac River was first begun to be filtered, and since that time the sand-filters have been subjected to systematic and most elaborate bacterial supervision, and improvements have been constantly introduced so as to secure the most efficient purification possible of the water before distribution, and the results are reflected in the marked diminution in typhoid fever which has followed these strenuous efforts to obtain the best water-supply available. The splendid example set by the State of Massachusetts, in promoting the welfare of the people by the encouragement of original researches in practical hygiene, has stimulated other American States to create Boards of Health and enact laws for the protection of their rivers and streams. In view of all that has been done to promote sanitary science in the United States, it is surprising to learn that Lake Michigan, which receives the untreated sewage of municipalities and small towns aggregating over two million people, still furnishes Chicago with its drinking water, and undergoes no preliminary purification before distribution. The city of Chicago, by constructing the Chicago Drainage and Ship Canal, opened in January, 1900, has diverted its own sewage from Lake Michigan, but this great sewer has only been made possible because of its advantages as a commercial waterway; and it has been stated, on high authority, that every project for the drainage of Chicago into the Illinois which has not recognised the waterway features has been predestined to failure. Dr. Egan, of the Illinois State Board of Health, however, points out that "with the present increase in population the Great Lakes, if they continue to be used as common sewers, will soon become totally unfit for use as drinking water, ... and one of two alternatives must be followed--either every source of water-supply must be filtered, or the sewage of the towns must be efficiently purified before it is allowed to flow into the lakes."