Two Steps After the Cut
Cutting a grain crop is only part of the job. The edible seed is still attached to the plant, held in a husk on a head of stalks. Two steps follow. Threshing breaks the grain loose from the heads and husks. Winnowing separates the loosened grain from the light chaff and bits of straw. Both steps were done by hand for most of history, and both were heavy, repetitive and dusty work.
Flails, Hooves and Wind
The simplest methods struck or trampled the cut grain. Workers beat sheaves with a flail, a hinged tool made from a handle and a swinging stick, on a hard floor of earth, stone or wood. In many regions, animals such as oxen or horses walked over the grain on a threshing floor. Some places used sledges with sharp stones or metal pieces drawn over the pile, and threshing boards of this kind appear in the Near East and Mediterranean.
Winnowing then used the wind. Workers tossed the mixture in the air with a shovel or flat basket, and the breeze carried off the light chaff while heavier grain fell back. A lack of wind meant a lack of progress, and some farmers built barns with opposite doors to create a draft. In China, a crank-driven rotary winnowing fan with a hopper and blades is recorded from ancient times, probably the Han period, long before similar devices appeared in Europe.
On many European farms, threshing was winter work for hired laborers, paid by the amount they threshed. A farmer could spend months of the cold season on it, which also made it a steady source of income for farm workers.
Early Mechanical Efforts
European inventors tried to reduce this burden. Winnowing machines, called fanners, spread in Britain and Europe in the early 1700s, using a hand-cranked fan to blow away chaff. They were controversial in some places, and there are stories of religious objections to artificial wind, though these are mostly retold anecdotes and should be treated with caution.
For threshing, early attempts in the 1700s imitated the flail by using rows of mechanical flails driven by water or horse power. These were complex and not very successful. A different idea was needed.
Meikle’s Drum
Andrew Meikle, a Scottish millwright, developed a threshing machine around 1786 that is widely regarded as the first commercially successful design. Its key feature was a rotating drum with beater bars that struck the grain against a fixed concave surface, rubbing it out of the heads rather than flailing it. Sheaves were fed in at one side, and straw and grain came out the other, to be separated and cleaned by additional machinery. Meikle’s patent and the efforts of others, including earlier work by people such as Michael Menzies, are part of a longer line of development, and credit is shared among several inventors.
Early threshing machines were large, fixed installations in barns. Water wheels, windmills or horse gins, which were round walkways where horses pulled a rotating beam, provided power. They were costly, so they appeared first on larger farms in Scotland and northern England, where farms were bigger and labor was relatively expensive. With the arrival of steam engines on farms in the early 1800s, portable threshing machines could be moved from farm to farm.
The Swing Riots
Labor was where the threshing machine proved most contentious. In the winter of 1830, agricultural workers in southern and eastern England, facing low wages, high unemployment and rising prices, destroyed threshing machines in what became known as the Swing riots, named after the fictitious “Captain Swing” whose name appeared on threatening letters. Machines were not the only grievance, since wages, rents and tithes also drove the unrest, but threshers symbolized the loss of winter work.
The authorities responded harshly. Many people were tried, and a number were executed or transported to Australia. Mechanization continued, and threshing machines became standard in England within a generation.
The American Thresher
In the United States, threshing machines developed in the early 1800s. Hiram and John Pitts of Maine patented a thresher and cleaner combination in 1837, and similar machines were built by many makers. Horse-powered “groundhog” threshers, small machines that were worked by a horse treadmill or a sweep, spread in the mid-1800s. Steam-powered separators followed, with their big traction engines pulling the equipment between farms.
Threshing season became a social event in many farming areas. Crews of men with wagons followed the machine, and neighbors shared labor and meals. At the same time, threshing was dangerous. Belts, gears and dust caused injuries, and explosions of boilers or dusty grain sometimes occurred.
Toward the Combine
The thresher steadily improved by adding straw walkers, sieves, fans and elevators. Power came from steam engines and then gasoline tractors and electric motors, and grain could be processed in far less time. Eventually the idea of bringing the thresher to the field and combining it with the cutting mechanism led to the combine harvester, and the separate threshing crew gradually disappeared.
Winnowing today takes place inside the machine, with fans and sieves, but the principle is the same as tossing grain in the wind: the heavier seed falls, and the lighter material blows away. In some places, small-scale farmers still thresh and winnow by hand or with simple tools.