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1. The specific mortality rates for males, females and the total population for England and Wales, for Scotland and for Sweden, have been fitted to a formula ƒ (t, θ) = α. (t—θ) βθ where ƒ (t, θ) is the specific mortality rate at a time t for age θ, β0 is a function depending solely on the age θ, and α (t —θ)depends only on the time of birth (t — θ). The results are in substantial agreement with those obtained by less refined methods in the previous paper. The probable errors of the values found for à and for β have been calculated.2. It is shown that the β0 curves for the Scottish and the English males are approximately represented by the Makeham-Gompertz formula A+Becθ, where A, B and c have suitable values. The other β0 curves do not appear to conform exactly to a formula of this type.3. With the help of the representation of β0 by the Makeham-Gompertz expression the effect of variation of α on the survival curves, the death curves, and the expectation of life has been determined. It is shown that with the range of values of α experienced in Britain during the last 50 years, the most marked effect is most likely to be experienced in the future between the ages of 65 and 85, a very considerable increase of people of these ages being likely provided that the relationship exhibited by the statistics up to the present date is maintained in the future.Though the Makeham-Gompertz formula does not hold in the case of the English and Scottish females, nor for the Swedish statistics, these approximate sufficiently closely to the values for the English and Scottish males, to allow of the conclusion deduced in the latter case being extended to the former.4. It is strongly emphasised that the validity of all the predictions depends upon a hypothesis of extrapolation which, however attractive in the light of the figures so far available, might not be fulfilled under certain contingencies.

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It does seem clear from the above series of results that of the factors examined in their relation to rickets, etc., the only one of substantial importance is differences in the manner of feeding. The absence of definite association with overcrowding is, certainly, surprising, in spite of the fact that we realise how crude is the measure of this factor which we have had to adopt. If, as we suggest, the personal factor is not a very serious one, the above findings afford at least prima facie evidence of the truth of the assertions made previously, and are certainly sufficient to warrant the prosecution of further field enquiries, on this line, but having greater regard to the obtaining of the necessary information in a form more suitable for detailed analysis.In this section the influence of five possible factors on the weight of the child has been considered. No one of these can be shown to be of outstanding importance in this respect; but the efficiency of the mother shows the highest and most consistent relationship. Health of mother and those variations of feeding which are considered here as indiscretions have no appreciable influence on infant weight, but the remaining two variables, overcrowding and position of the infant in the family, seem to influence the weight of the child. In the case of overcrowding, the effect is small and only becomes substantial towards the end of the first year. Position of the infant in family, likewise, is of little moment; first and latest-born infants initially seem to have lower than average weights, but towards the end of the first year of life the weights of first-born infants tend to be over average, while those of infants born into already large families still show evidence of inferiority.