fever, provided, of course, that the sewers are used for the purpose for which they are intended, aud that streets and back yards no longer serve as receptacles for filth, as was usual during the presanitary period even in great cities like London and Paris. The axiom 'tout a l'égout' now governs the practice not only in Paris, but wherever the fundamental principles of municipal sanitation are understood and sewers have been constructed. Unfortunately, the cost of sewer construction, the reluctance of tax-payers to part with their money and the ignorance or indifference of municipal authorities have conspired to prevent the accomplishment of this fundamental sanitary measure in very many towns in the United States, and our endemic plague—typhoid fever— continues to claim a large annual quota of victims in such localities. Even in the national capital our sewer system is incomplete and in many out-of-the-way places, especially in the densely populated alleys of the city, shallow box privies are in use as receptacles for human excreta and the typhoid fever rate, owing to this and other causes, is disgracefully high.
Mortality rates in towns and cities throughout the civilized world depend to a large extent upon the purity of the water-supply and the efficiency of the system of sewage disposal; and the constant improvement which is shown by the mortality statistics of England and other countries which have made the most progress in this direction is undoubtedly largely due to these two factors. This is well illustrated by the mortality statistics of armies. In the German army the annual death-rate in 1868 was 6.9 per thousand, a decade later it was 4.82, in 1888 it had fallen to 3.24 and in 1896 to 2.6. In our own army, the death-rate during the period of peace just prior to the Mexican War (1848) was about three and one half times as great as during the five years preceding our recent war with Spain, and since the year 1872 there has been a diminution of the death-rate of nearly forty per cent. In the British army at home stations the mortality rate during the decade ending in 1884 was 7.2 per thousand, in 1889 the rate had fallen to 4.57 and in 1897 to 3.42. In the Italian army there has been a gradual and progressive reduction from 13.3 per thousand in 1875 to 4.2 in 1897. The mortality in the French army was a little over 21 per thousand during the five years ending in 1825. In 1890 it had fallen to 5.81 per thousand.
According to the best estimates the average of human life in the sixteenth century was somewhat less than twenty years. At the present time it is more than twice as long and during the past twenty-five years the average duration of life has been lengthened about six years. During the first thirty-five years of the past century the vital statistics of the city of London showed a mortality of about 29 per thousand. At the present time the mortality in that great city has been reduced to from
