THE FECUNDITY AND FERTILITY OF WOMEN. 



487 



40 to 50 call themselves 40, we might expect the smaller ordinates belonging to 

 higher ages to be pushed back, as it were, towards 30 and 40, thereby apparently 

 accounting for the two depressions which appear in the curve about those ages. 

 That this is no fancied explanation may be gathered from the following scan- 

 dalous facts recorded in the Census Report of 1851, p. xxiv. : — 



In 1841 the number of girls, of ages 10-15 was . . . 1,003 119 



But in 1851 these had become young women aged 20-25, and numbered . 1,030,456 



This number, when corrected from the tables of mortality, obviously includes 

 about 140,000 women whose ages had increased by less than 10 in ten years ! 



Again, in 1841 the number of women aged 20-25 was 

 But in 1851 those who had reached 30-35 were only 



973,696 

 768,711 



indicating at first sight a fearful death-rate, but really showing how strong is the 

 desire to be considered as remaining under the magic limit of thirty years of age. 

 To complete the examination, however, let us see how far these data from 

 sterility agree with the formula deduced by the other processes. 



Fecundity. 



Age. 



15-19 



20-24 



25-29 



30-34 



35-39 



40-44 



45-49 



Percentage not Sterile, 



92-7 



100 



72-3 



62-5 



46-8 



91 



4-4 



3^(50— age) 



113 1 



96 



78-9 



61-8 



44-5 



27-4 



104 



It is easy, of course, to construct a formula to represent any series of numbers, 

 but unless it be simple it is of little use ; and the approximation we have got 

 seems close enough, if we remember the almost certain deficiencies in the numbers 

 for the two highest ages, and the immaturity, &c, which may easily be supposed 

 to account for that at 15-19. But there is another cause which may serve to 

 account for part of the discrepancy, as in fact Dr Duncan's table shows. This is 

 that plural births are not eliminated. In fact, at age 20-24 there are a good 

 many more children per annum than mothers in his table, which thus virtually 

 assumes that no woman of 20-24 is sterile. This accounts for the great rise in 

 the (dotted) curve at the age of 22. 



By the process of § 3 we form the first line of the following table. The 

 second is formed on the type Y t = \k (50— tf. 



Fertility. 



Age. 



15-19 



20-24 



25-29 



30-34 



35-39 



40-44 



45-49 



F t from/ t observed, 



387-8 



2951 



1951 



120-8 



603 



13-5 



44 



«5 (60 -' )2 



414 



298 



202 



123 



64 



24 



4 



