even in some cases as much as five per cent. per annum, yet, as each of our principal coal-fields becomes occupied, the power of progressive increase must inevitably decline.
This result may be already observed to prevail in the earlier developed coal-fields— as compared with the more newly developed districts; Northumberland, Durham, South Staffordshire, and Lancashire, may be accepted as examples of the earlier developed fields, where the available coal ground has been more fully let out and apportioned for working than in either the Midlands, South Wales, Scotch, or North Staffordshire fields—and the effect of this check to the development of new collieries by the coal ground being already occupied, may, the writer suggests, be observed in the respective rates of increase in the output within the ten years ending with last year. Northumberland and Durham for the 10 years increased 11 per cent. South Staffordshire, 2 per cent. Lancashire 16 per cent. Whilst on the other hand, the Midlands showed an increase of about 34 per cent., South Wales nearly 40 per cent., Scotland 30 per cent., North Staffordshire 20 per cent., and therefore the rapid annual increase of the output in the past will not be a safe guide to gauge the rate of progress of the output in future years.
Further, it is well known that under ordinary circumstances, a larger output from particular collieries is obtainable where thick and easily worked seams are in course of working, as compared with the output from the same collieries when thinner or harder seams are in course of working.
On the whole, the writer considers that another quarter of a century of progress, at the rate of 2 to 3 per cent. per annum, will probably complete the occupation of the best of our coal-fields, and attain probably the maximum of our national output of coal. This maximum output may probably be maintained for another quarter of a century, to be followed by a slow but gradual reduction in the annual output, the annual rate of this reduction pending upon many conditions, which it is of course impossible at the present time to predicate.
The operation will doubtless be very gradual, commencing in the earlier developed coal fields, and gradually extending to the larger coal-fields of the Midlands and South Wales, and in the end increasing permanently the cost of producing coal.
Upon a small scale the effect may already be observed in more than one of the older coal districts, where the working of thinner seams at an increased cost has both increased the cost of working and checked the increase of the rate of output, owing to the com-
