An apparatus for separating the grain from the straw. Machines for this purpose were contrived as far back as 1732; these were considerably improved by Mr. Andrew Meikle, in 1785, who took a patent for his improvements, which are described in the "Repertory of Arts." Since that time they have undergone various ameliorations; and the construction of those which are mostly employed at the farm-houses, may be briefly described as consisting of three rotatative drums or cylinders; around the first which comes into operation are a series of arms, or beaters, which are made to revolve, and thereby strike the corn (supplied underneath them by feeding rollers,) with great rapidity. Hence the thereshed corn is carried on by the motion of the feed rollers, to two successive straw shakers, which consist (as before mentioned) of a rotative frame, armed with numerous spikes, that lift up and shake the straw, so as to force from amongst it the grain, and allow it to fall through a grated floor, into a large hopper beneath. From this hopper the corn is conducted to another receptacle, and in its passage winnowed by fanners driven with great velocity, that separate the chaff, by blowing it away into another receptacle.
Of course the power by which such machines are driven depends upon local circumstances; but in general a horse-wheel is employed, worked by the united force of three horses; the horse-wheel is mounted with a large horizontal wheel. which drives a pinion on the main shaft of the threshing-machine; and the main shaft, by suitable gear, gives motion at the requisite velocities to the parts we have described.