The Wealth of Nations by Part 1 Chapter 11 Page 155

In 1688 was granted the Parliamentary bounty upon the exportation of corn. The country gentlemen, who then composed a still greater proportion of the legislature than they do at present, had felt that the money price of corn was falling. The bounty was an expedient to raise it artificially to the high price at which it had frequently been sold in the times of Charles I and III. It was to take place, therefore, till wheat was so high as forty-eight shillings the quarter, that is, twenty shillings, or five-sevenths dearer than Mr. King had in that very year estimated the grower’s price to be in times of moderate plenty. If his calculations deserve any part of the reputation which they have obtained very universally, eight-and-forty shillings the quarter was a price which, without some such expedient as the bounty, could not at that time be expected, except in years of extraordinary scarcity.