192 



PRESIDENT S ADDRESS. — SECTION G. 



It is evident that the above rate of increase in the use of 

 aluminium can continue only for a limited period. The average 

 annual value of this rate, viz., 28.16 per cent, for the first three 

 years, diminished to 9.27 per cent, for the neixt ten, then rose 

 to 32.91 per cent, for the next five years, and to 36.09 per cent, 

 for the last three years. This rate is, of course, enormous, and 

 implies the doubling of the production every 2.2495, say, two and 

 a quarter years, or multiplying it by sixteen for every nine years' 

 duration, a rate which, of course, could not be long maintained.* 

 None of the rates of increase can be long continued. 



It has, of course, often O'ccurred to scientific thinkers and to 

 economists that the present rate of living is extravagant and that 

 we are using up Nature's bounties without stint. This indict- 

 ment is perhaps only too true. 



6. Fossihilities of Fond Supply and of Water Supply for Cities. 

 ■ — Disregarding the squandering of our resources, let us return 

 to the question of the possibility of sufficient food supplies and 

 ask', "Can thes© supplies be enormously increased?" 



It is not unfrequently alleged that as-yet-undreamt-of dis- 

 coveries in physics and chemistry and altogether better methods 

 of agriculture will admit of progress being indefinitely continued. 

 This is based upon a misconception of the significance of rates 

 of increasei — of the nature of increase by the law of " coinpo'und 

 "interest." All advance depending upon human ingenuity is vilti- 

 mately governed by the law of " diminishing returns." It may 

 for ever continue, but will proceed by smaller and smaller 

 amounts, that is, the curve representing it is convex upwards. 

 On the other hand, the curve of compound interest is concave 

 upwards, and a few simple calculations will show that we cannot 

 properly found any expectation of relief upon such jjossibilities 

 ot ingenious advance. 



Let us take a concrete case which has relation to the food 

 supply. The " world production " of cereals in million " short 

 tons'"' (2,000 lbs.) from 1895 to 1916 was as follows: — 



* The rate 0-3609 implies that in about 47 years the production would be increased over 

 2,000,000 fold. 



