beneficial effects to mankind, it may be said, like mercy, to shed its gentle dews from heaven; and, by being the prime cause of annihilating distances, it has brought the human race closer together, and is thus the "one touch of nature that makes the whole world kin."
It is not only the most useful but it is the most valuable of all minerals, on account of the wealth that is produced through its agency. It is well understood that money is a sequence of work, and a community that has small labor-bills can take the trade away from those that have to pay high rates. Let us, therefore, see what work this substance can produce.
In mechanics the unit of work is the power necessary to raise one pound one foot high, and this is known as a foot-pound. From numerous experiments and observations, an able-bodied man, in working ten hours a day, exerts an average force of 1,000,000 foot-pounds. When coal is burned under a boiler it produces steam, which in turn produces work as it drives machinery. Therefore, coal produces work, the amount of which will vary according to the perfection of the machinery and the appliances for generating the steam. If we take an average of all kinds of engines, one pound of coal will produce steam sufficient to exercise a power of 500,000 foot-pounds. Hence the work accomplished by two pounds of the fuel equals a man's day's work. Now, mark the surprising results to which this leads us. The population of the United States is about 40,000,000, and in 1877 we produced 50,000,000 tons of coal. If one-fourth of this were applied to manufacturing, etc., it would do as much work as our whole population, assuming them all to be able-bodied men, in 350 days. The coal at the engine will average about four dollars a ton, while the price of unskilled manual labor can be put down at one dollar a day. Applying these figures, we see that the work in the first case would have cost $50,000,000; while in the latter, were it even possible to employ so many men, the labor-bill would have been $14,000,000,000! Can any one for a moment question the advantage or the value of the substance?
In these days, accustomed as we are to its multitudinous uses, it is difficult to imagine ourselves in the position of the early writers, who touched with uncertain pen on what they thought to be the leading characters of a rare and ambiguous mineral, or to conceive that its introduction was accompanied by such prejudice and superstition that laws were actually passed forbidding its use by the very countries that now consider it as the greatest of their possessions. In fact, it is of comparatively late date that it has sprung into the important position which it now occupies.
The earliest express mention made of it as a fuel was about 300 b. c., in the writings of Theophrastus, the pupil of Aristotle, who speaks of it as being found in Liguria (now the province of Genoa) and in Elis on the way to Olympias, where it was used by smiths. Ampelitis, a black stone "like bitumen," is mentioned by Pliny as available for
