246 



lotka: a natural population norm 



and, for the fraction of the population comprised between the 

 ages fli and a^. 



I 



c (a) da = h {A\ - A\r + A'.r^ - A'^r^ + • • • ) 



(5) 



^e 



co/c. 



10 7.0 Jo ^0 5** ^° 7" *" ^^ '*'*' 



Fig. 3. Age-Distribution in the living population, England and Wales 1871- 

 1880. Areas represent numbers of persons. Both Sexes. 



In these series the constant coefficients are given by 



1 r°° 



An = — 1 a^p{a) da 

 n ! Jo 



A'„ 



1 f^' , 

 — a° ?? (a 



n I J&x 



) da 



(6) 

 (7) 



