The importance of Jamaica to Great-Britain, consider'd : with some account of that island ... with an account of their trade and produce, with the advantages they are of to Great-Britain, Ireland, and the colonies in North America, and the commodities they take in return from them ... in a letter to a gentleman : to which is added, a postscript, of the benefits which may arise by keeping of Carthagéna, to Great-Britain and our American colonies.