smaller share in their prices than in that of most other parts of the rude produce of land. The rent of an estate above ground commonly amounts to what is supposed to be a third of the gross produce; and it is generally a rent certain and independent of the occasional variations in the crop.

In coal-mines a fifth of the gross produce is a very great rent; a tenth the common rent, and it is seldom a rent certain, but depends upon the occasional variations in the produce. These are so great that, in a country where thirty years’ purchase is considered as a moderate price for the property of a landed estate, ten years’ purchase is regarded as a good price for that of a coal-mine.

The value of a coal-mine to the proprietor frequently depends as much upon its situation as upon its