president's address. 17 



for the re-conversion of electrical energy into mechanical work; and 

 it is this power of work which gives us leisure, and which enables a 

 small country like ours to support the population which inhabits it. 



I suppose that it will be generally granted that the Commonwealth 

 of Athens attained a high-water mark in literature and thought, which 

 has never yet been surpassed. The reason is not difficult to find ; a 

 large proportion of its people had ample leisure, due to ample means; 

 they had time to think, and time to discuss what they thought. How 

 was this achieved? The answer is simple: each Greek Freeman had 

 on an average at least five helots who did his bidding, who worked his 

 mines, looked after his farm, and, in short, saved him from manual 

 labour. Now, we in Britain are much better off; the population of 

 the British Isles is in round numbers 45 millions ; there are consumed 

 in our factories at least 50 million tons of coal annually, and ' it is 

 generally agreed that the consumption of coal per indicated horse- 

 power per hour is on an average about 5 lb.' (Boyal Commission on 

 Coal Supplies, Tart I.). This gives seven million horse-power per 

 year. How many man-power are equal to a horse-power? I have 

 arrived at an estimate thus: a Bhutanese can carry 230 lb. plus his 

 own weight, in all 400 lb., up a hill 4,000 feet high in eight hours; 

 this is equivalent to about one-twenty-fifth of a horse-power; seven 

 million horse-power are therefore about 175 million manpower. Taking 

 a family as consisting on the average of five persons, our 45 millions 

 would represent nine million families ; and dividing the total man-power 

 by the number of families, we must conclude that each British family 

 has, on the average, nearly twenty ' helots ' doing his bidding, instead 

 of the five of the Athenian family. We do not appear, however, to 

 have gained more leisure thereby, but it is this that makes it possible 

 for the British Isles to support the population which it does. 



We have in this world of ours only a limited supply of stored-up 

 energy; in the British Isles a very limited one — namely, our coalfields. 

 The rate at which this supply is being exhausted has been increasing 

 very steadily for the last forty years, as anyone can prove by mapping 

 the data given on page 27, table D, of the General B-eport of the Boyal 

 Commission on Coal Supplies (1906). In 1870, 110 million tons were 

 mined in Great Britain, and ever since the amount has increased by 

 three and a third million tons a year. The available quantity of coal in 

 the proved coalfields is very nearly 100,000 million tons; it is easy to 

 calculate that if the rate of working increases as it is doing our coal will 

 be completely exhausted in 175 years. But, it will be replied, the rate 

 of increase will slow down. Why? It has shown no sign whatever 

 of slackening during the last forty years. Later, of course, it must 

 slow down, when coal grows dearer owing to approaching exhaustion. 

 It may also be said that 175 years is a long time ; why, I myself have 

 1911. c 



