THRASHING or THRESHING, the process by which the grain or seed of cultivated plants is separated from the husk or pod which contains it. The flail was the chief means of thresh ing grain until about 186o.
The flail consisted of two pieces of wood, the handstaff or helve and the beater, fastened together loosely at one end by a thong of rawhide or eelskin, which made a very durable joint. The handstaff is a light rod of ash about 5 ft. long, slightly in creasing in girth at the farther end to allow for the hole for the thong to bind it to the beater; its length enabled the operator to stand upright while working. The beater is a wooden rod about 3o in. long, made of ash, though a more compact wood such as thorn is less likely to split. This also has a hole at one end for the thong to bind it to the handstaff. The shape of the beater was cylindrical, of about 14 in. diam. and constructed so that the edge of the grain of the wood received the force of the blow; 3o to 4o strokes per min. was the average speed.
After the grain had been beaten out by the flail or ground out by other means the straw was carefully raked away and the corn and chaff collected to be separated by winnowing when there was a wind blowing. This process consisted in tossing the mixture of corn and chaff into the air so that the wind carried away the chaff while the grain fell back on the thrashing floor. The best grain fell nearest while the lightest was carried some distance before falling, thus a rough-and-ready grading of the grain was obtained. It was also performed when there was no wind by fanning while pouring the mixture from a vessel. Later on a fanning or winnowing mill was invented.
The flail is still in use for special purposes such as flower seeds and also where the quantity grown is so small as to render it not worth while to use a thrashing mill. For a day's work with it a fair average quantity was 8 bushels of wheat, 3o bushels of oats, 16 bushels of barley, 20 bushels of beans, 8 bushels of rye or 20 bushels of buckwheat.
Meikle's first really successful thrashing ma chine—the type which is embodied in modern thrashers—was in vented by a Scotsman named Andrew Meikle in 1786. In this
the loosened sheaves were fed, ears first, from a feeding board between two fluted revolving rollers to the beating cylinder. This cylinder or "drum" was armed with four iron-shod beaters or spars of wood parallel to its axle, and these striking the ears of corn as they protruded from the rollers knocked out the grain. The drum revolved at zoo to 25o revs. per min. and carried the loose grain and straw on to a concave sieve beneath another re volving drum or rake with pegs which rubbed the straw on to the concave and caused the grain and chaff to fall through. Another revolving rake tossed the straw out of the machine. The straw thus passing under one peg drum and over the next was sub jected to a thorough rubbing and tossing which separated the grain and chaff from it. These fell on to the floor beneath, ready for winnowing.
The present-day thrashing machine embodies the main features of Meikle's and will thrash up to 16 qrs. of oats per hr., accord ing to its size. For further details see HARVESTING MACHINERY.
Thrashing Work.—The minimum number of hands required in Great Britain are: An engine-driver, a feeder, a sackman and ten other men to handle the sheaves, straw, chaff, grain, etc., while half as many more may be needed where the sheaves or grain have to be carted, as when the thrashing is done in the field in harvest time. An 8-h.p. steam engine is the usual motive power, but the development of the oil engine has provided a very satisfactory substitute. The engine is usually of the "trac tion" type, so that it can move the thrashing machine or "barn work" (as it is sometimes called) and elevator from place to place, but a further advance has been to combine oil engine and thrasher in one so that the combination is self-moving. The usual quantities thrashed with a "double blast finishing ma chine," as described, in the United Kingdom are, with a 5 ft. wide drum, from 6o to 8o bushels per hour of wheat and one third to one-half more of oats and barley.