316 THE BORDERLAND OF SCIENCE. 



the mere expansion of the uses already discovered for 

 the mineral), but an increase of that increase, on 

 account chiefly" of the progress of invention and 

 discovery. 



That this state of things will continue for several 

 years to come may fairly be anticipated; that for many 

 years to come the average rate of increase in the coal- 

 consumption will be fully equal to that at present 

 observed may also be expected ; but that, before many 

 years are passed, the rate of increase (then higher than 

 now) will be beginning to diminish, thenceforward 

 returning towards its present rate, and passing even- 

 tually below its present rate, is to be looked forward to 

 as the natural order of events in the future. Let it be 

 remembered that such a result would by no means 

 imply a falling off in the commercial and manufacturing 

 activity of the country. The extension of the employ- 

 ment of coal for known uses has, in several instances, 

 already nearly approached a limit. In other cases, such 

 extension, though still proceeding, is not proceeding 

 at an increasing but at a decreasing rate. This must 

 happen in turn with all the known applications of coal, 

 the extension of its use perhaps attaining a rate cor- 

 responding nearly to that of the actual growth of our 

 population.* Such a change would imply a continual 



* The population is increasing at an increasing rate at present ; but 

 as this rate is much lower than that at which the consumption of coal 

 is increasing, this consumption, in changing to the rate at which popu- 

 lation is increasing, must diminish its rate of increase. Moreover, the 

 increase of the rate at which the population of this country is increas- 

 ing, grows less, decade by decade. 



