LAWS OF THE FERTILITY OF WOMEN. 289 



tility of continued married life in England and Scotland. Malthus was well 

 aware of the real meaning of these figures, — of the fact that they merely show the 

 relative frequency of marriage ceremonies and births in a population. " The rule," 

 he says,* " which has been here laid down, attempts to estimate the prolificness 

 of marriages, taken as they occur; but this prolificness should be carefully distin- 

 guished from the prolificness of first marriages andof married women, and still 

 more from the natural prolificness of women in general, taken at the most favour- 

 able age. It is probable," he adds, "that the natural prolificness of women is 

 nearly the same in most parts of the world ; but the prolificness of marriages is 

 liable to be affected by a variety of circumstances peculiar to each country, and 

 particularly by the number of late marriages." 



As a corollary from the preceding data, of value only in proportion to their 

 value, it may be stated that the average duration of fertility in married women 

 (including those who do not bear children) is about 7\ years. For, as the inter- 

 vals between marriage and the birth of a child, and between the births of succes- 

 sive children, is, on an average, 20 months, and as there are about 4| children to 

 each marriage, we have about 7| years, counting from marriage, spent in pro- 

 ducing that number. 



British authors, as Graunt, Short, Malthus, Sadler, Senior, and those of 

 later date, name 4, 4 J, or 5, as the fertility of marriage. Malthus, founding on such 

 data, gives a wife eight years of fecundity to produce four children, a statement 

 which cannot be passed over without the obvious remark that Malthus, so calcu- 

 lating, utterly neglects the force of the wise words which we have just quoted 

 from his work. 



I have nothing satisfactory to offer as to prolific marriages, to contrast with 

 the statements given concerning all marriages. Dr Lever f says, that " the ave- 

 rage number of children consequent upon a prolific (not every) marriage is shown 

 to be rather more than 5f , but not amounting to 6." This is given without any 

 authority stated or evidence detailed, and I know not what value to ascribe to it. 

 In a physiological point of view, its value must be scarcely appreciable ; for no 

 allowance is made for the duration of the marriage, nor for the age of the woman 

 at the time of the ceremony. 



In St George's-in-the-East, London, the average number of children consequent 

 on the prolific marriages was 5 to each marriage. $ That is, 5 is the average 

 number of children that has been born in all the families in a place at a given 

 time. It tells nothing concerning the average number in completed families, or in 

 still-growing families. § 



* Essay on the Principle of Population, vol. ii. p. 6. 

 t On Organic Diseases of the Uterus, p. 5. 



% Quarterly Journal of the Statistical Society of London, vol. xi., 1848. 



§ Some interesting facts regarding the fertility of Esquimaux women are to be found in 

 Roberton's " Essays and Notes on Physiology and Diseases of Women," p. 53. 



