THE DYNAMIC VALUE OF COAL.
Rogers, in his Geology of Pennsylvania, has given a very curious state ment of the force or power derived from the combustion of certain amounts of coal, which, while it presents an approximate estimate and conveys to the mind an idea of the mechanical force thus derived, is very erroneous in statement and fact. He estimates the average duty of the improved Cornish pumping-engine as equivalent to 100,000,000 pounds lifted one foot high by the consumption of one bushel, or 84 pounds, of coal, and then takes the maximum duty as 125,000,000 under the same circumstances. By dividing the bushel of 84 pounds into the maximum duty, 125,000,000, he makes one pound of coal raise 1,500,000 pounds one foot high, or equivalent to the labor of a strong man on the tread-mill during 10 hours; and thus he estimates that (4) four tons of coal is equal to twenty years of manual labor, or an average lifetime of hard work. By this ingenious estimate, 10,000,000 tons of coal are made to supply England each year with a mechanical force, as applied to the production of steam, equal to 3,500,000 fresh men laboring through 20 years.
We give this singular statement, not only for the purpose of correcting it,—since it has been widely circulated,—but to show that even a practical application of this force, as applied to mechanical effect, will increase the value of manual labor a hundredfold.
The average "duty" of 35 Cornish pumping-engines at work in Eng land during 1864 was 500,000 pounds lifted one foot high with a con sumption of one pound of coal. But in an estimate of this character we cannot ,assume even the average consumption of the Cornish engine to be the rule, since the consumption of coal to the power produced, by the ordinary English engines, is at least double. We presume that 200,000 pounds lifted one foot high by the combustion of one pound of coal is nearer to the rule than the exception.
But we will place our figures still lower, and make 10 pounds of coal, as applied to the production of mechanical power through the agency of steam, as equal to a day's work, or tons of coal as equal to a year of manual labor. 10,000,000 tons of coal, thus applied, adds to the pro
ductive labor of England a force equal to the exertion of 7,500,000 fresh men annually The amount specified,-10,000,000 tons,—as used for the production of steam in England, is, perhaps, much below the actual consumption. It is estimated that 100,000,000 tons of coal were produced by the mines of Great Britain in 1864, or nearly 90,000,000, as sent from the mines. But all practical miners are aware that a large amount of coal is consumed at the mines.
In 1861 the production of the great northern coal-field, in Northumber land and Durham, was 21,777,570 tons. Of this amount, 19,077,570 tons were sold or sent from the mines, leaving 2,700,000 burned for home con sumption and wasted at the mines. The same proportion used at the mines generally would swell the amount to over 100,000,000. This vast, almost incomprehensible, mass of coal has been produced by 300,000 men and boys at 3000 collieries.
The number of collieries is constantly decreasing, though their pro ductions are increasing. In 1860 there were 13 collieries more than in 1861, while the production of coal was one million of tons less.
The great northern coal-field, in Northumberland and Durham, is the greatest coal-producing district. In 1861 there were 271 collieries in operation, employing nearly 50,000 men and boys, while the production and distribution of coal from these collieries were The above is, perhaps, an average distribution of the English coals, and, it will be noticed, over one-fifth, or 5,000,000, of this amount,—included in steam, manufacturing, and line consumption,—is made use of for the production of steam. From this data we may safely estimate that one tenth, or 10,000,000 tons, of the entire production of Great Britain is applied to mechanical purposes in labor-saving operations. The estimate, therefore, which makes the coal of England add to her resources of labor the equivalent of 7,500,000 strong men per annum, is not exaggerated.