A true and impartial account of the rise and progress of the South Sea Company : wherein the Assiento contract is particularly considered : proving the great advantages that would have accrued to England by a faithful observance of it on the part of Spain : with observations on a late pamphlet, intituled, Considerations on the American trade, before and since the establishment of the South Sea Company, detecting the many gross misrepresentations of the author, humbly addressed to Admiral Vernon /