births, females preponderate in the entire population. This excess of females in the English population would be still larger but for the large proportion of the population living at the earlier ages, when the number of males considerably exceeds that of females. The proportion of the two sexes would be somewhat altered if the number of Englishmen engaged abroad in the army, navy, and merchant service were taken into account. The differences of mortality due to variations in sex-distribution are usually so small that they may be in practice neglected. The distribution of the population as to age and sex favours a low mortality (1) In newly settled communities. (2) In towns, and especially when they are rapidly increasing; and (3) In manufacturing as compared with agricultural neighbourhoods. The high mortality which usually holds in such populations would be still higher but for their favourable age and sexconstitution. Dr. Ransome gives an example which may serve to illustrate differences in the general rate of mortality, due simply to varying age-distribution of population. Suppose two towns, A and B, each with 1,000 inhabitants, and exactly alike in their sanitary conditions. A has 150 children under five; B has only 100 under five, which in each case die at the rate of 10 per cent. per annum, while persons over five die at the rate of 10 per mille. Reckoning up the total mortality per 1.000 at all ages, we find that In A, out of 150 children, 15 die. 850 over 5, 85 die; equal to 23.5 per 1,000 of the entire population. In B, out of 100 children, 10 die. 900 over 5,9 die; equal to 190 per 1,000. Thus there is a difference of 45 per 1,000 in the death-rate, due simply to differences in the composition of the two populations, and apart altogether from their state of health. Dr. Ransome further points out that a death-rate of ten or even twelve per 1,000, which is not infrequently recorded in certain favoured districts, cannot be regarded as a true measure of longevity of its inhabitants. A death-rate of ten per 1,000 means either that every child born attains the age of one hundred before he dies, or else that the average age at death is one hundred, and that if some die in infancy, others must have lived much more than a hundred. Similarly, a death-rate of twelve per 1,000 means an average age at death of over eighty. "Under present conditions such figures are not attained by any community in the world, and can only be looked for in the millennium, when, as Isaiah says, the child shall die an hundred years old." There are only two ways of avoiding the fallacies involved in unequal age and sex-constitution of populations submitted to comparison: (1) The method to be immediately described; and (2) A statement of the death-rate at various groups of and in the two sexes, as given in the next chapter. ages, Method of Correction for Age and Sex-Distribution.-The Registrar-General described, in his Annual Summary for 1883, the method of correcting the death-rates in the twenty-eight great towns, giving in parallel columns the recorded and corrected death-rates for each town. This has been continued for subsequent years, and I append the table for 1887, the towns being arranged in the order of their corrected death rates. In the preceding table the standard death-rate signifies the death-rate at all ages, calculated on the hypothesis that the rate at each of twelve age periods in each town was the same as in England and Wales during the ten years 1871-80, the death-rate at all ages in England and Wales during that period being 21-27 per 1,000. The factor for correction is the figure by which the recorded death-rate should be multiplied in order to correct for variations of sex and age-distribution. The corrected death-rate is the recorded death-rate multiplied by the factor for correction. The comparative mortality figure represents the corrected death-rate in each town, compared with the recorded deathrate, at all ages, in England and Wales, taken as 1,000. The figures in this column may be read as follows:- After making approximate correction for differences of age and sexdistribution, the same number of living persons that gave 1,000 deaths in England and Wales in 1887 gave 925 in Brighton, 949 in Derby, etc., etc., and 1,701 in Manchester. The first column in the preceding table is obtained by assuming that the mean mortality in England and Wales in 1871-80 held good in each town. The age and sex-distribution of each town at the last census being known, the mean mortality in England and Wales, 1871-80, is applied toʻthe population thus constituted, and we have as a result the series of death-rates in Col. 1. The differences between the various towns in this column are consequently caused simply and solely by difference in age and sex-distribution. As an example of the method of obtaining these standard death-rates, Brighton may be taken. Here the total population of Brighton in 1881=107,546. The standard death-rate will therefore = 20.66 per 1,000, which corresponds with the rate given in the table on page 92. Now the annual death-rate of England and Wales in 1871-80 was 21.27. This ought to be the same as the calculated deathrate for Brighton, which has been obtained by applying the mean annual death-rate of England and Wales at the different age-groups to the population of Brighton at these age-groups. But the death-rate for Brighton is lower, as shown above, which must arise from the fact that the distribution of age and sex in the Brighton population is more favourable than in the country generally. That this is so will be seen more clearly from the following table, in which population per 1,000 is given : the composition of each England & Wales 1,000 136 120 108 98 90 146 113 83 59 33 14 Brighton 1,000 117 104 100 103 99 159 118 88 62 35 15 53 49 51 It is evident that there is a considerably larger proportion of females in the Brighton population, and that while there is a much smaller number of children under 5, there is only a slightly larger proportion of persons over 55, or in other words, at the ages of high mortality. The standard death-rate being lower for Brighton must be |