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Other coal mines in the same country, sufficiently fertile,

cannot be wrought on account of their situation. A quantity of

mineral, sufficient to defray the expense of working, could be

brought from the mine by the ordinary, or even less than the

ordinary quantity of labour: but in an inland country, thinly

inhabited, and without either good roads or water-carriage, this

quantity could not be sold.

Coals are a less agreeable fuel than wood: they are said too to

be less wholesome. The expense of coals, therefore, at the place

where they are consumed, must generally be somewhat less than

that of wood.