For the present purpose it is sufficient to connect the rate of marriage with that of births by using as a basis for the former the number of women of conceptive age, or between 15 and 45 years old.
Here the annual number of legitimate births is shown in its proportion to the mean number of married women of conceptive age at each of the three latest enumerations.
On the other hand, the postponement of marriage in the case of women of conceptive ages is a tendency which seems to be growing in other countries as well as in England and undoubtedly has a depressing effect upon the rate of births.
It is necessary, therefore, to eliminate the difference in the age-constitution of the countries in question by excluding from the field of observation, as before, all except possible mothers, basing the rate upon the respective numbers of women of the conceptive age, that is between 15 and 45.
The cessation of assisted immigration early in the life of the present generation is alleged to have had considerable influence upon the rate, in Victoria, at least, owing to the curtailment of the supply of adult women of the more conceptive ages and the ageing of those who had reached the country at an earlier date.
Are calculated upon the number of women most likely to produce them, that is, the spinsters, widows and divorced of conceptive age.
Marriage and child-bearing, in the first place, are operative amongst a fraction of the population only - those of conceptive age; whereas to the Urn of Death, as Dr Farr expressed it, all ages are called upon to contribute in their differing degrees.