Collery of production of mineral combustibles in these states, likewise in the year 1845:

| Country | Tons | |------------------|----------| | Great Britain | 21,600,000 tons | | Belgium | 4,360,077 tons | | United States of America | 4,180,000 tons | | France | 4,141,617 tons | | Prussia | 3,500,000 tons | | Austria | 700,000 tons |

Fig. 17.

From this diagram we find, that Great Britain (although considerably underrated) produces seven times more than the United States of America, from six to seven times more than Belgium; from seven to eight times more than France, and nine times more than Prussia.

According to recent estimates, the annual produce of coal in Great Britain considerably exceeds 40,000,000 tons. At the present rate of consumption, the coal deposits of Great Britain will still last more than 1500 years; and by an improved method of working, viz., "longwall," this time might be extended at least 400 years. It may require some time to introduce this mode of working for economizing coal-fields; but it is nevertheless a point deserving of careful consideration (seeing that our most valuable and easily obtained seams are at present being rapidly exhausted), and sufficiently important to enlist the interest of a great manufacturing country, whose commercial success is in a great measure dependent upon her collieries or coal mines.

Coal is plentifully distributed throughout that division of the earth's crust termed by geologists the coal measures. It is readily recognised from the strata in which it is found. It has a blackish appearance, is of less specific gravity (than the other strata), and is very inflammable when brought in contact with heat and flame.

If we omit the earthy impurities, which, when burnt, are known as ashes, and which vary from 0-2 to upwards of 40 per cent. "coal is essentially composed of carbon, oxygen, hydrogen, and nitrogen; and the quality of the coal depends upon the relative proportion of these ingredients."

This important mineral is extensively used in navigation; it is the indispensable aliment of industry; and in cold or temperate climates is essential to the health and comfort of the inhabitants.

The following diagrams will convey an approximate idea of the respective areas of coal formation in the principal coal-producing countries of Europe and America. (See Taylor's Statistics of Coal)

United States of America. Bituminous Coal. 133,182 square miles.

Anthracite of Pennsylvania. 437 sq. miles.

Great Britain and Ireland. 3720 sq. miles. Anthracite and Cullm.

Great Britain. Bituminous Coal. 8139 sq. miles.

British America. Bituminous Coal. 18,000 sq. miles.

France. 1719 sq. miles.

Belgium. 518 sq. miles.

Spain. 2408 sq. miles.

Fig. 18.

(W. A.)