100 THE LAW OF BIRTHS AND DEATHS 



these defects the general correlation between birthrates 

 and deathrates is remarkable. M. Muret, writing in 1766, 

 was so struck by the fact that a low deathrate is always 

 accompanied by a low birthrate a fact ascertained by him 

 as the result of careful researches in Switzerland that 

 he hazarded the conjecture that " God has wisely ordered 

 things in such a manner that the force of life in each 

 country should be in the inverse ratio of its fecundity." * 

 It is in comparing the rates for large areas that the 

 correlation is most readily traced, and that is because 

 the principle will act through the law of averages. The 

 larger the area, the more effectively do disturbing factors 

 in either direction counterbalance and cancel each other. 

 If a number of towns be taken, while there is still a general 

 correlation between birthrates and deathrates, there is 

 a great deal of irregularity. Much of this is simply 

 statistical. Movements of population profoundly affect 

 statistical results, especially when the figures are compiled 

 upon the system of showing the rates per thousand of 

 population. For instance, tables compiled upon that 

 method credit Australia and New Zealand with a higher 

 birthrate than Ireland. The reason is that there is a 

 large emigration from Ireland and a large immigration 

 into Australia and New Zealand. This leaves Ireland 

 with a disproportionate number of old people and children 

 in the population left behind, since emigrants consist 

 mainly of young people in the prime of life. For the 

 same reason new countries like Australia and New Zealand 

 have a disproportionately large number of inhabitants 

 of child-bearing age, and also a better balance between 

 the sexes. And when tables are given which make the 

 necessary allowances for these facts it is found that 

 Ireland has a very high rate of fertility, while Australia 

 1 The Principle of Population, Malthus, Book II, chap. v. 



