The sinking of a pit, even to a less depth than a hundred fathoms, sometimes demands, notwithstanding all the improvements by machinery, a sum of not less than a hundred pounds a fathom, or ten thousand pounds for the whole pit; and therefore, supposing it possible for a single man to do it at the rate of eighteen pence a day, the time which he would require would be between four hundred and five hundred years. Whence comes it that the labour of between four hundred and five hundred years is reduced to a single day? and that which, independently of the carriage, would have cost ten thousand pounds, is got for eighteen pence? It is because man joins with man, and machinery is employed to do the drudgery. Nations that have no machinery have no coal fires, and are ignorant that there is hidden under the earth a substance which contributes more, perhaps, to the health and comfort of the inhabitants of Britain than any other commodity which they enjoy. No nations have worked coal to anything approaching the extent in which it has been worked by our countrymen. It has been calculated that France, Belgium, Spain, Prussia, Bohemia, and the United States of America, do not annually produce more than seventeen million tons of coal, which is about half of our annual produce.[20] [Illustration: Steam-Boiler making.] The greater part of the coal now raised in Britain is produced by the employment of the most enormous mechanical power. There are in some places shallow and narrow pits, where coals may be raised to the surface by a windlass; and there are others where horse-power is employed. But the number of men that can work at a windlass, or the number of horses that can be yoked to a gin, is limited. The power of the steam-engine is limited only by the strength of the materials of which it is formed. The power of a hundred horses, or of five hundred men, may be very easily made by the steam-engine to act constantly, and on a single point; and thus there is scarcely anything in the way of mere force which the engine cannot be made to do. We have seen a pit in Staffordshire, which hardly gave coal enough to maintain a cottager and his family, for he worked the pit with imperfect machinery--with a half-starved ass applied to a windlass. A mile off was a steam-engine of 200-horse power, raising tons of coals and pumping out rivers of water with a force equal to at least a thousand men. This vast force acted upon a point; and therefore no advantage was gained over the machine by the opposing force of water, or the weight of the material to be raised. Before the steam-engine was invented, the produce of the coal-mines barely paid the expense of working and keeping them dry; and had it not been for the steam-engines and other machinery, the supply would long before now have dwindled into a very small quantity, and the price would have become ten or twenty times its present amount. The quantity of coal raised in Great Britain