In 1900 759,900 people were employed in Great Britain in the mining of coal, the per-head out put being 296 tons. As the depth of the mines becomes greater and the more profitable deposits approach exhaustion, greater difficulty and ex pense will attend the mining operations. In fact, the per-head product has already begun to de cline. The Royal Commission, reporting in 1871, claimed that if the rate of consumption and the population both increased in the future as in the past, the supply would last 276 years. The recent rapid progress made by certain other coun tries in the same field threatens England's su premacy in those industries which have drawn so heavily on its coal resources, and it is not uncommonly thought that the past rate of in crease in the annual coal output will not be sustained and that the supply will last a much longer period than the one mentioned.
In mediaeval and ancient times in Great Brit ain, other varieties of minerals were relatively of much greater importance than coal and iron. It is a matter of tradition that centuries before the Christian Era the Phoenician merchants visited England and traded in the products of the tin-mines of Cornwall. Whether this be true or not, it is certain that the Cornish mines have been worked from a very early period. During the early part of the Middle Ages, down to the time when the tin-mines of Bohemia and Saxony were discovered, England supplied almost all the tin that was used throughout Christendom.
Sir Walter Ralegh's famous report of 1603 on the state of trade and commerce mentions tin and lead as the chief minerals produced. In the Roman period the mining of lead was carried on so extensively that it was limited by law. Cop per and silver were also mined. The revenue from the Devonshire tin and lead mines paid the ex penses of the French wars of the fourteenth cen tury. But these minerals were mined with diffi culty, and the great modern improvements in transportation have made it more economic many cases to import the ore, thus tending to check the home production. English clays have always been used in the making of pottery, and used extensively after the introduction of the im proved methods by the Dutch and Huguenot im migrants. The combined annual output of cop per, tin, salt, and other minor minerals was estimated at the beginning of the century at $5,000,000 in value; in 1840, at about $15,000, 000; and at about the same figure forty years later; the total value is not materially dif ferent at present. The country's abundant sup ply of useful stone has always been drawn upon, and there has been a very rapid increase in its utilization in recent years. In 1900 the value of the sandstone quarried was estimated at $7, 930,225; the granite at $6,193,735; the limestone at $6,501,570; and slate and slab at $7,641,680.