means of paying his expenses, and obtaining the ordinary profits of stock. It appears, then, that it is always the least fertile mine which regulates the price of coal. Adam Smith, however, is of a different opinion: he observes, that "the most fertile coal mine too regulates the price of coals at all the other mines in its neighbourhood. Both the proprietor and the undertaker of the work find, the one that he can get a greater rent, the other, that he can get a greater profit, by somewhat underselling all their neighbours. Their neighbours are soon obliged to sell at the same price, though they cannot so well afford it, and though it always diminishes, and sometimes takes away altogether, both their rent and their profit. Some works are abandoned altogether; others can afford no rent, and can be wrought only by the proprietor." If the demand for coal should be diminished, or if by new processes the quantity should be increased, the price would fall, and some mines would be abandoned; but in every case, the price must be sufficient to pay the expenses and profit of that mine which is worked without being charged with rent. It is therefore the least fertile mine which regulates price. Indeed it is so stated in another place by Adam Smith himself, for he says, "The lowest price at which coals can be sold for any considerable time, is like that of all other commodities, the price which is barely sufficient to replace, together with its ordinary profits, the stock which must be employed in bringing them to market. At a coal mine for which the landlord can get no rent, but which he must either work himself, or let it alone all together, the price of coals must generally be nearly about this price."
But the same circumstance, namely, the abundance and consequent cheapness of coals, from whatever cause it may arise, which would make it necessary to abandon those mines on which there was no rent, or a very moderate one, would, if there were the same abundance, and consequent cheapness of raw produce, render it necessary to abandon the cultivation of those lands for which either no rent was paid, or a very moderate one. If, for example, potatoes should become the general and common food of the people, as rice is in some countries, one fourth, or one half of the