298 



DR MATTHEWS DUNCAN ON THE 



Speaking of the interval between marriage and a first birth, Sadler* gives the 

 following indefinite statement: — "Married females do not become fruitful, on 

 the average, during the first year of their nuptials, but nearly so. A great 

 number of cases which I have collected, with a view of determining this point, 

 give three-fourths of them as producing their first child at the average of one year 

 after marriage." 



Whitehead,! founding on the observation of 541 married women, of the 

 average age of 22 years, makes out the average interval between marriage and 

 the birth of a first child, to be 1L| months. 



Quetelet^: admits, with sufficient probability, as an average term, that the 

 birth of the first-born takes place within the first year which follows marriage. 

 His error, as those of the others, depends on the acknowledged want of docu- 

 ments. 



It next comes to be inquired at what rate children succeed each other in 

 families. This interesting topic is developed from the data given in Table VI. 

 It is formed by dividing the whole years of duration of sets of marriages, of dif- 

 ferent durations, by the number of children born in the corresponding marriages ; 

 and it must be remembered, that as our data all spring from women who were 

 fertile on the year of our census or counting, no women are included who, although 

 fertile formerly, have now ceased to be so ; and it is evident that, for the purposes 

 of our argument, this is just. 



TABLE VI. — Showing the Average Duration op Marriage at Birth of each Suc- 

 cessive Child ; and the Average Interval between the Births of the Succes- 

 sive Childken.§ 



Number 



of 



Child. 



Number 



of 

 Mothers. 



Duration of 



Marriage 



in Months. 



Average interval 

 between suc- 

 cessive Births. 



Number 



of 

 Child. 



Number 



of 

 Mothers. 



Duration of 



Marriage 



in Months. 



Average interval 

 between suc- 

 cessive Births. 



1 



2 

 3 

 4 

 5 

 6 

 7 

 8 

 9 

 10 



3,722 



2,893 



2,534 



1,982 



1,543 



1,221 



848 



641 



425 



222 



17 



38 



64 



90 



115 



137 



162 



181 



203 



225 



17-0 

 190 

 21 3 

 22-5 

 230 

 228 

 231 

 226 

 22-5 

 225 



11 

 12 

 13 

 14 

 15 

 16 

 17 

 18 

 19 



152 

 61 



34 



11 



6 



2 



2 



1 

 1 



235 

 246 

 263 

 281 

 280 

 336 

 252 

 252 

 204 



214 

 20-5 

 202 

 20-1 

 18-7 

 210 

 148 

 14-0 

 10-7 



Average 



19-9 



**The Law of Population, vol. ii. p. 30. f On Abortion and Sterility, p. 242. 



J Treatise on Man, p. 15. 



§ This is not a correct statement of the contents of this Table. The last column does not 

 directly give the average interval between the births of successive children, but the average interval 

 between marriage and the birth of the child, divided by the number of the children born. For 

 brevity's sake, the title is left as it stands. 



