THE GOAL QUESTION. 79 



years. From 1854 we know precisely the annual rate of 

 increase: in 1854 it was sixty-four and a half million tons; in 

 1874 it will be nearly double that, we can safely predict; for 

 though the last published returns only are for 1871, still at that 

 time the annual yield was one hundred and seventeen and one- 

 third millions; and knowing the annual rate of increase, it will 

 be fully one hundred and twenty millions in 1872 ;"^* in 1873 it 

 will be nearly one hundred and twenty-four millions; and in 

 1874 it will be over one hundred and twenty-seven, or nearly 

 double the sixty-four and a half millions it was twenty years 

 before. 



It was Professor Jevons who first showed the annual increase 

 was not simply an addition in arithmetical ratio, but in a 

 geometrical ratio. It increased something like a sum at 

 compound interest increases differently from one at simple 

 interest. Writing in 1865 from the ten years that were known, 

 he obtained the rate of increase, and from that he calculated 

 forwards how much coal would have been consumed in the next 

 one hundred and ten years from that time. And he came to this 

 remarkable result, — that by the end of that time, if our prosperity 

 held, we should have used all the available coal that was known 

 to be within reasonable depth, i.e., within four thousand feet. 

 This was a prospect that struck many with alarm, and coal 

 owners in particular were unwilling to accept either his argument 

 or conclusions. The greater part however of his opponents, as 

 he says in his second edition, misunderstood him; others actually 

 conceded the points which he was endeavouring to prove without 

 foreseeing the conclusion it led to. Some disputed that the rate 

 would coutinue to increase as it had done ; some great authorities 

 writing several years after Professor Jevons, were of opinion 

 that the output would never go beyond one hundred and fifteen 



* From the <' Mineral Statistics" for 1872, (published December, 

 1873) it appears that the coal raised amounted actually to 123,497,316 

 tons. 



