With the increased demand for corn and meat from the towns the necessity of new and better implements became apparent, and many patents were taken out: by Praed, for drill ploughs, in 1781; by Horn, for sowing machines, in 1784; by Heaton, for harrows, in 1787; for sowing machines, by Sandilands, 1788; for reaping machines, by Boyce, 1799; winnowing machines, by Cooch, 1800; haymakers, by Salmon, 1816; and for scarifiers, chaff-cutters, turnip-slicers, and food-crushers.[516] But the great innovation was the threshing machine of Meikle. Like most inventions, it had forerunners. The first threshing machine is mentioned in the _Select Transactions of the Society of Improvers in the Knowledge of Agriculture in Scotland_, published in 1743 by Maxwell. It was invented by Michael Menzies, and by it one man could do the work of six. One machine was worked by a great water-wheel and triddles, another by a little wheel of 3 feet diameter, moved by a small quantity of water. The first attempts to substitute horse or other power for manual in threshing were directed to the revolution of jointed flails, which should strike the floor on which the corn was spread, but this proved unsatisfactory, so that rubbing the grain out of the straw by revolving cylinders was tried,[517] Young, in his northern tour, met a Mr. Clarke at Belford in Northumberland, who was famous for mechanics,[518] among his inventions being a threshing machine worked by one horse, which does not seem to have effected much. Eventually Mr. A. Meikle, of Houston Mill near Haddington, in 1798 erected a machine the principles of which, much modified, are those of to-day; and in 1803 Mr. Aitchison, of Drumore in East Lothian, first applied steam to threshing. It was some time, however, before this beneficent invention was generally used, and when the machines were used they were usually driven by horse--or water-power until about 1850. In 1883 Messrs. Howard, of Bedford, adapted a sheaf-binding apparatus to the threshing machine. With new implements came new crops; the Swede turnip was grown on some farms in Notts just before 1800, but it is not known who introduced it.[519] The mangel wurzel was introduced about 1780-5 by Parkyns, and prickly comfrey in 1811.