180 WHAT WE OWE TO OUR COAL-FIELDS. 



must always be left in the process of extraction. Under 

 these circumstances, and with a consumption that has 

 trebled itself within the last thirty years, it is not to be 

 wondered that some uneasiness has "Been felt as to the du- 

 ration of our coal supply, and a Royal Commission been 

 appointed (1866) to inquire into the probable amount that 

 still lies un worked, and which seems to be fairly accessible. 

 "Whatever be the issue of the inquiry, two things are certain 

 first, that the supply is limited, and that at the present 

 rate of consumption it will be wholly exhausted in a few 

 hundred years; and, second, should the coal-measures be 

 found to extend under the newer formations, it would be im- 

 possible, with our present appliances, to extract the mineral 

 at these enormous depths, and even if engineering skill were 

 enabled to surmount the difficulty, the increased cost would 

 be tantamount, in all ordinary cases of consumption, to 

 closing the supply. In the mean time, and without dwell- 

 ing on this most unwelcome prospect, our duty is clearly 

 to encourage every plan for the fuller and more careful ex- 

 traction of the mineral, and to do what we can, individually 

 and nationally, to economise the consumption. 



Regarding IRON as the product of next importance, it 

 may be said to occur in two varieties in our coal-fields 

 namely, as a rough clay-carbonate in bands and nodules, 

 and as a finer clay-carbonate in beds of varying thickness, 

 and mingled less or more with coaly or bituminous matter. 

 The former constitutes the " clay-band " of the miner, and 

 the latter the " black-band " the former being the more 

 abundant, the latter the more valuable as containing enough 

 of coaly matter for its calcination without the addition of 

 extraneous fuel. There are other and more abundant sources 

 of iron than the coal-formation (the haematites and siderites) ; 

 but, considering that these ores cannot be reduced to the 

 metallic state without the addition of fuel, the conjunction 



