188 



PRESIDENT S ADDRESS. — SECTION G. 



productive age, are consequently dependent upon the older popula- 

 tion for their maintenance. As the point is of importance and 

 popularly is by no means clearly apprehended, I shall indicate 

 in more detail the nature of this proposition. 



Given a series of constant rates of mortality according to age, 

 an increasing population, growing by natural increase, will change 

 the relative numbers in age-groups, by heaping up the relative 

 numbers of those living at the younger ages. Thus, if a popula- 

 tion were constant and were characterized by the rates of mortality 

 in Australia (for males) between 1901 and 1911, the grouping 

 would be continually as on the first line hereunder (0 per cent.), 

 while if the number of births incre-ased 3 per cent, annually, in 

 105 years when all the first generation had passed away, it would 

 be as shown on the second line (3 per cent.). 



Initially, the birth-rate and death-rat© would be each 18.12 per 

 1,000; but finally the birth-rate would have reached 41.33 per 

 1,000 and the general death-rate would have fallen to 11.77, 

 leaving the annual rat© of natural increase — originally zeroi — 

 29.56 per 1,000, or, say, about 3 per cent. 



We see, then, that if a community grows by natural increase 

 at the rate of 3 per cent. , its accumulations have to bear the strain 

 of supporting, say, about 42 per cent, of its population instead of 

 about the 22 per cent, if it merely mad© good its deaths by its 

 births. This is, of course, a considerable financial burden, and, 

 other things being equal, tends to reduce the wealth per head; 

 in short, the condition of increase is that the population shall be 

 hard-working and thrifty. 



It is appropriate here to consider in a general way what are 

 the conditions of increase of population. They may b© set out in 

 the form of a conspectus, as follows : — - 



Increase is caused by : — 



I. Promotion of human fertility. 

 II. Development of food and water 

 supplies. 

 III. The practice of thrift. 



Diminution is caused by : — 



I. Restriction of human fertility. 

 II. Inadequacy of food and water 



supplies. 

 III. Indifference to thrift and 

 general extravagance. 



