The greatest drawback of this system is the fact that it encourages overcrowding of houses on inadequate areas, and, unfortunately, it is this fact which has rendered the system so popular. With water under pressure there is no need to provide houses with any back-door or back-yard, and there is no inconvenience in having excessively high buildings. The speculative builder, who has been relieved of all responsibilities in connection with sewage and water supply, has abundantly used his opportunities, and the happy ground-landlord has sold his land at large prices per square foot. We are shutting out the light and air more and more from our cities, and the crowding in the streets is making locomotion in them difficult. This overcrowding is a serious matter, and I will show what it means in London by means of a table and diagrammatic plan of the sanitary areas of London, with the mortality figures in the years 1892 and 1893, as calculated by Mr. Shirley Murphy, after due correction for abnormalities of age and sex distribution. This table and plan (p. 144) shows at a glance that the mortality of London as a whole (taken as 1,000) is 14 or 15 per cent. higher than that of England and Wales, and that while some of the outlying districts, such as Hampstead, Lewisham, and Plumstead, have a mortality below that of England and Wales, the areas near the centre of London are all considerably above it; and some, such as the Strand, Holborn, St. George's-in-the-East, and Whitechapel, have a mortality as high as that of the worst manufacturing towns. The danger of overcrowding is well shown by the explosive outburst of small-pox in Marylebone in 1894. MORTALITY FIGURES (Figures in small type show the population of the Sanitary Areas)