I20 POPULAR SCIENCE MONTHLY. 



years, owing to the composition of the population, has its birth-rates 

 momentarily increased and its death-rates diminished — the birth-rates 

 because there are more people relatively at the child-producing ages, 

 and the death-rates because the whole population is younger, than in 

 older countries. It appears quite unnecessary to elaborate this point. 

 The rates of the excess of births over deaths in a country which is 

 receiving a large immigration must be quite abnormal compared with 

 a country in a more normal condition, while a country from which 

 there is a large emigration, such as Ireland, must tend to show a lower 

 excess than is consistent with a normal condition. This explanation, it 

 may be said, does not apply to England, since it is a country which has 

 not been receiving a large immigration or sending out, except occa- 

 sionally, a large emigration. England, however, must have been 

 affected both ways by movements of this character. It received un- 

 doubtedly a large Irish immigration in the early part of last century, 

 and in more recent periods the emigration in some decades, particularly 

 between 1880 and 1890, appears to have been large enough to have 

 a sensible effect on both the birth-rate and the rate of the excess of births 

 over deaths. This efCect would be continued down into the following 

 decade, and the consideration is therefore one to be taken note of as 

 accounting in part for the recent decline in birth-rates in England. 



In addition, however, it is not improbable that there was an 

 abnormal increase of population in the early part of last century, due 

 to the sudden multiplication of resources for the benefit of a poor 

 population which had previously tended to grow at a very rapid rate, 

 and would have grown at that rate but for the checks of war, pestilence 

 and famine, on which Malthus enlarges. The sudden withdrawal of 

 the checks in this view would thus be the immediate cause of the 

 singularly rapid growth of population in the early part of last century. 

 It is quite in accordance with this fact that a generation or two of 

 prosperity, raising the scale of living, would diminish the rate of growth 

 as compared with this abnormal development, without affecting in any 

 degree the permanent reproductive energy of the people, 



3. It is also obvious that one explanation of the decline in birth- 

 rate, and of the rate of the excess of births over deaths, may also be the 

 greater vitality of the populations concerned, so that the composition 

 of the population is altered by an increase of the relative numbers of 

 people not in the prime of life, so altering the proportion of the people 

 at the child-producing ages to the total. This would be too complex a 

 subject for me to treat in the course of a discursive address. Nor would 

 it explain the whole facts, which include, for instance, an almost sta- 

 tionary annual number of births in the United Kingdom for more than 

 ten years past, notwithstanding the largely increased population. But 

 the case may be one where a great many partial explanations contribute 



