of consumption, of which the returns are made regularly once in the year, can keep in constant employment, in the country to which it belongs, a quantity of productive labour, equal to what a thousand pounds can maintain there for a year. If the returns are made twice or thrice in the year, it can keep in constant employment a quantity of productive labour, equal to what two or three thousand pounds can maintain there for a year. A foreign trade of consumption carried on with a neighbouring, is, upon that account, in general, more advantageous than one carried on with a distant country; and, for the same reason, a direct foreign trade of consumption, as it has likewise been shown in the second book, is in general more advantageous than a round-about one.
But the monopoly of the colony trade, so far as it has operated upon the employment of the capital of Great Britain, has, in all cases, forced some part of it from a foreign trade of consumption carried on with a neighbouring, to one carried on with a more distant country, and in many cases from a direct foreign trade of consumption to a round-about one.