490 PROFESSOR TAIT ON THE FERTILITY AND FECUNDITY OF WOMEN. 



Scottish marriages have any foundation in fact, their consideration would tend 

 to make the difference in fertility between the two countries even greater than 

 that just given ; for legitimation per subsequens matrimonium. does not put a child's 

 name on the Registrar's books. 



17. The fact that in England and Scotland the quantities 2/j.Y and I/jlF are 

 almost exactly proportional to the number of marriages in the two countries, 

 shows that, although Scottish women, as a rule, marry later in life than English 

 women, the long period (25-40) during which their marriage-rate exceeds that in 

 England, as compared with the shorter period '(20-25), during which it falls 

 behind, almost makes up for the diminished fertility at the more advanced age. 



18. It only remains to construct the values of the quantities F t for each country, 

 taken, of course, from the mass of the wives. 



As before (§ 15), we should have had 



if we had used proper absolute values of F. But we used the numbers 12, 8*9, G, 

 &c, which are obviously too large. Reducing them all in the ratio 6 to 1, and 

 substituting for /?, &c, their values, we get 



96,693=20,597x7-55 e. 



This gives 



e=0622. 



from which we construct the following table of 



Fertility of the Mass of Wives. 





15-19 



20-24 



25-29 



30-34 



35-39 



40-44 45-49 



Scotland, .... 

 England, .... 



7-44 

 604 



5-54 

 4-49 



377 

 302 



2-30 

 187 



1-24 

 1-01 



0-37 

 0-30 



006 

 005 



19. In conclusion, it may merely be repeated that we have attempted no elabo- 

 rate or exact inquiry into this question ; indeed the utter insufficiency of data 

 would have rendered such a proceeding absurd; and we have, for the same 

 reason, abstained from employing some of our own results, such as those of § 10, 

 in modifying the earlier ones, by the help of which they have been arrived at. 

 Thus, for instance, we should be led by the results of § 10 to use in the formulae 

 of §§ 5, 6, a number somewhat less than 50, as corresponding to the average age 

 of sterility. As in all questions of average, the value of our deductions in this 

 matter is mainly dependent on the extent and accuracy of our data, and it is sad 

 to think that the enormous blue-books which load our shelves contain so much 

 painfully-elaborated information which is of no use, and so little of those precious 

 statistics which would at once be easy of acquirement and invaluable to physio- 

 logists. 



