The main factors in the reduction of typhus fever have been the immobilisation of infectious cases in fever hospitals, the rigid cleansing and disinfection of invaded households, and the surveillance of persons who have been exposed to infection. The clearing of insanitary courts, housing improvements, and the associated increased cleanliness of the general population have doubtless aided; and it is a suggestive fact that although the virus of typhus is not yet determined, and although it has only recently been shown that typhus is a louse-spread disease, the point of extinction of the disease under peace conditions has almost been reached in countries having an efficient sanitary organization and a cleanly people. With the demonstration that typhoid fever was commonly water-borne, that the spread of typhus fever could be controlled by sanitary surveillance and immobilisation of infectious cases in hospital, and that diarrhœal mortality could be reduced by increased municipal and domestic cleanliness, much more rapid improvement in national health occurred in the decennium 1871-1880 and in subsequent years. The course of events for typhoid and typhus fever has already been noted. Before describing further the action taken by central and local public health authorities and the other influences conducing to reform, it is convenient to summarise at this point the _General Results in the Saving of Life_ Although I do not dwell further on the influence of increase of wages, of better and cheaper food, of sanitary education of the people, of a steadily increasing standard of cleanliness,—in person and in spitting habits,—and of improving home conditions, it will not be assumed they must be omitted in any considered judgment as to the means by which the saving of life shown by the following figures has been secured. The expectation of life at birth (or mean after-lifetime) in England and Wales in 1871-80 for males was 41.4 years, for females 41.9 years. It steadily improved decade by decade; based on the experience of 1910-12 the male expectation of life had been prolonged by 10.1 years, and the female by 10.8 years. A very large proportion of the lives saved were lived in the years of greatest value to the community. Comparing 1910-12 with 1871-80, the reduction of the death-rate meant that _each year_ 116,401 male and 118,554 female lives were saved, and the future lifetime of these persons whose lives were prolonged,—assuming a continuance of current experience,—would give an annual gain of nearly ten millions of additional years of life, of which over seventy per cent. would be lived at ages 15 to 65.