478 On the Fruitfulness of Marriages. Bk. ii. 



of marriage. If the population be increasing, 

 the marriages of the present year have resulted 

 from a smaller number of births than the births of 

 the present year, and of course the marriages, 

 compared with the contemporary births, will al- 

 ways be too few to represent the proportion of 

 the born which lives to marry ; and the contrary 

 will take place if the population be decreasing ; 

 and, to find this proportion, we must compare the 

 marriages of any year with the births of a previ- 

 ous year at the distance of the average age of 

 marriage. 



But on account of the distance of this period, 

 it may be often more convenient, though it is not 

 essentially so correct, to compare the marriages 

 with the contemporary deaths. The average age of 

 marriage will almost always be much nearer to the 

 average age of death than marriage is to birth; 

 and consequently the annual marriages compared 

 With the contemporary annual deaths will much 

 more nearly represent the true proportion of the 

 born living to marry, than the marriages compared 

 With the births.* The marriages compared with 



* Dr. Price very justly says (Observ. on Revers. Pay. vol. i. 

 p. 269. 4th. edit.) " that the general effect of an increase while it 

 " is going on in a country is to render the proportion of persons 

 *' marrying annually, to the annual deaths greater and to the an- 

 " nnal births less than the true proportion marrying out of any 

 " given number born. This proportion generally lies between the 

 " other two proportions, but always nearest the first." In these 

 observations I entirely agree with him, but in a note to this pas- 

 sage he appears to me to fall into an error. Fie says, that if the 

 prolifickness of marriages be increased (the probabilities of life and 



