wholly or partially exhaustible; such as coal, and most if not all metals; for even iron, the most abundant as well as most useful of metallic products, which forms an ingredient of most minerals and of almost all rocks, is susceptible of exhaustion so far as regards its richest and most tractable ores.
When, however, population increases, as it has never yet failed to do when the increase of industry and of the means of subsistence made room for it, the demand for most of the productions of the earth, and particularly for food, increases in a corresponding proportion. And then comes into effect that fundamental law of production from the soil, on which we have so frequently had occasion to expatiate; the law, that increased labour, in any given state of agricultural skill, is attended with a less than proportional increase of produce. The cost of production of the fruits of the earth increases, cæteris paribus, with every increase of the demand.
No tendency of a like kind exists with respect to manufactured articles. The tendency is in the contrary direction. The larger the scale on which manufacturing operations are carried on, the more cheaply they can in general be performed. Mr. Senior has gone the length of enunciating as an inherent law of manufacturing industry, that in it increased production takes place at a smaller cost, while in agricultural industry increased production takes place at a greater cost. I cannot think, however, that even in manufactures, increased cheapness follows increased production by anything amounting to a law. It is a probable and usual, but not a necessary, consequence.
As manufactures, however, depend for their materials either upon agriculture, or mining, or the spontaneous produce of the earth, manufacturing industry is subject, in respect of one of its essentials, to the same law as agriculture. But the crude material generally forms so small a portion of the total cost, that any tendency which may exist to a progressive increase in that single item, is much over-balanced by the diminution continually taking place in all the other elements;
