Once again the arrivals and departures by the gates of life and death were recorded. In the ten years from the 1st of April, 1891, to the 31st of March, 1901, 1,329,428 births had been registered, and 838,454 deaths. The excess of births over deaths, therefore, was 490,974; and as the increase of population was 309,228, it followed that 181,746 persons had migrated. As the migration had only been 114,000 in 1891, it was manifest that migration to outside the County of London was increasing. The total number of inhabited houses was 571,768, as against 547,146 in 1891; but owing to a variation in the manner of collecting the information, the figures have little value for comparative purposes. The accurate figures given of the population of London enabled the death-rate to be calculated on facts instead of upon estimates. The death-rate was 17·1 per 1,000 living in 1901, a decrease from 18·6 in the previous year, and from 21·0 in 1891. But to be set against this was the portentous fact that the birth-rate had declined from 31·8 per 1,000 in 1891 to 29·0 per 1,000 persons living in 1901, the lowest recorded in London since civil registration began. The public health of London was now altogether on a better level than it had been before, but in the course of the year 1901 some cases of smallpox appeared in various parts of London, and in 1902 there was the most severe outbreak of it--with the possible exception of 1884-5--since 1871, nearly 9,000 cases being admitted to the hospitals of the Metropolitan Asylums Board between September, 1901, and July, 1902. Ninety-three patients were removed to hospital in one day, and on one day (March 11th) 1,604 cases were under treatment. Over 1,300 persons died of it in the year. The cost of disease to the community has often been referred to in previous chapters. The Metropolitan Asylums Board stated that so far as it was concerned, the cost for 1901-2 might be put at £500,000--equal to about a threepenny rate--a sum which was wholly apart from loss of wages to the individual, and various other expenses, and apart from the charge upon the rates of those who were pauperised by the death of the breadwinner of the family. 1903 was "a year of comparatively very slight prevalence of infectious disorders." In 1904 there was "a marked absence of undue activity amongst the infectious diseases of the metropolis." And 1905 was the healthiest year in the records of London since registration, the death-rate being 15·1 per 1,000. In the five years which have passed since the census of 1901, Parliament has passed three Acts of the utmost consequence to the sanitary condition of the people of London, marking, in their respective spheres, definite stages in the sanitary evolution of the metropolis. The sanitary evils to which many of the people were subject might, as has already been stated, be roughly divided into two classes--those of their dwellings at night, and those of their workplaces in the day.