?14 35. It is the Hindu portion of the population among which the greatest fluctuations take place ; and an examination of the following table and curve serves to indicate the extraordinary effect upon the total mortality of the City produced during the past few years by this variation in the population :- Year. Deaths among Hindus. Deaths among Mussulmans. Deaths among all other classes. 1902 34,729 10,211 3,474 1903 36,709 10,246 3,558 1904 30,246 9,176 3,254 1905 35,010 9,342 3,410 1906 39,106 10,065 3,703 1907 26,847 8,714 3,126 1908 25,725 9,216 3,330 1909 23,332 8,352 3,194 Mean 31,463 9,415 3,381 Number of deaths above and below the mean and percentage variation, are shown below :- Deaths above and below the mean and percentage variation. Year. Hindus. Mussulmans. Other classes. 1902 +3,266 = +10.3 per cent. +796 = + 8.4 per cent. + 93 = +2.7 per cent. 1903 +5,246 = +16.6 “ +831 = + 8.8 “ +177 = +5.2 “ 1904 -1,217 = -3.8 “ -239 = - 2.5 “ -127 = - 3.7 “ 1905 +3,547 = +11.2 “ -73 = - 0.7 “ + 29 = + 0.8 “ 1906 +7,643 = +24.2 “ +650 = + 6.9 “ +332 = + 9.5 “ 1907 -4,616 = -14.6 “ -701 = - 7.4 “ -155 = -4.5 “ 1908 -5,738 = -18.2 “ -199 = - 2.1 “ -51 = -1.5 “ 1909 -8,131 = -25.8 “ -1,063 = - 11.2 “ -181 = - 4.2 “ Mean variation 4,925 = 15.6 per cent. 589 = 6.2 per cent. 142 = 4.2 per cent. Mean variation above the mean 4,925 = 15.6 per cent. 759 = 8.0 per cent. 155 = 4.5 per cent. Mean variation below the mean 4,925 = 15.6 per cent. 455 = 4.8 per cent. 128 = 3.7 per cent. The mean population of Hindus during the 8 years was probably about 500,000, that of Mussulmans about 150,000 and of other classes about 90,000. The latter class, which includes Parsis, Native Christians, Europeans and Eurasians, is probably less liable to great fluctuations than either Hindus or Mussulmans ; and the difference between the mean variations in the annual mortality among Hindus and members of this class indicates the probable fluctuation of mortality due to excessive or reduced migration. In the dry season of 1906 the Hindu population was probably swollen to a figure 10 to 15 per cent. above the average dry weather population and in 1908 and 1909 it was from 15 to 20 per cent. below it. From 60 to 80 per cent. of the apparent improvement in mortality during the past few years is probably due to diminished migration from the rural districts owing to better monsoons and increased prosperity. 36. Death-rates.-Total mortality figures give but a slight indication of the true state of the public health and it is usual for comparative purposes to make use of death-rates, that is the ratio of persons dying each year to the total population living. For calculating death-rates it is necessary to have an estimate of the total population, and the figures obtained at each decennial census are made use of for this purpose. In Great Britain it is customary to calculate the population living in each year of the inter-censal periods and to base birth and death-rates upon these figures ; but in India no such correction is made, birth and death-rates being calculated upon the census population.