The Wealth of Nations by Part 4 Chapter 5 Page 112

The 13th of the present king, c. 43, seems to have established a new system with regard to the corn laws in many respects better than the ancient one, but in one or two respects perhaps not quite so good.

By this statute the high duties upon importations for home consumption are taken off so soon as the price of middling wheat rises to forty-eight shillings the quarter; that of middling rye, pease or beans, to thirty-two shillings; that of barley to twenty-four shillings; and that of oats to sixteen shillings; and instead of them a small duty is imposed of only sixpence upon the quarter of wheat, and upon that of other grain in proportion. With regard to all these different sorts of grain, but particularly with regard to wheat, the home market is thus opened to foreign supplies at prices considerably lower than before.