Page:Principles of Political Economy Vol 1.djvu/605

Rh increased by restrictive laws, is no burthen on the consumer: it does not raise the price of corn, and is no otherwise a detriment to the public, than inasmuch as if the state had retained it, or imposed an equivalent in the shape of a land-tax, it would then have been a fund applicable to general instead of private advantage.

§ 3.Agricultural productions are not the only commodities which have several different costs of production at once, and which, in consequence of that difference, and in proportion to it, afford a rent. Mines are also an instance. Almost all kinds of raw material extracted from the interior of the earth—metal, coals, precious stones, &c., are obtained from mines differing considerably in fertility, that is, yielding very different quantities of the product to the same quantity of labour and capital. This being the case, it is an obvious question, why are not the most fertile mines so worked as to supply the whole market? No such question can arise as to land; it being self-evident, that the most fertile lands could not possibly be made to supply the whole demand of a fully-peopled country; and even of what they do yield, a part is extorted from them by a labour and outlay as great as that required to grow the same amount on worse land. But it is not so with mines; at least, not universally. There are, perhaps, cases in which it is impossible to extract from a particular vein, in a given time, more than a certain quantity of ore, because there is only a limited surface of the vein exposed, on which more than a certain number of labourers cannot be simultaneously employed. But this is not true of all mines. In collieries, for example, some other cause of limitation must be sought for. In some instances the owners limit the quantity raised, in order not too rapidly to exhaust the mine: in others there are said to be combinations of owners, to keep up a monopoly price by limiting the production. Whatever be the causes, it is a fact that mines of different degrees of richness are in operation, and