THE CAUSES OF THE DECLINING BIRTH RATE 151 



Ages at Marriage of Workmen in York 



That the fertility of different classes is not caused entirely by 

 the greater duration of marriage of the people who marry at an 

 earlier age is indicated by the English statistics on the fecundity 

 of marriages of different durations in the different groups. Mar- 

 riages of a given degree of duration from two years up to thirty 

 show uniformly a much higher fertility among the laborers than 

 among the professional classes. 



Fecundity According to Duration of Marriage of Followers of Different 



Occupations 

 (British Census of 1911) 



