To separate and drive off the chaff from by means of wind; as, to winnow grain. To examine; to sift for the purpose of separating falsehood from truth; to separate, as bad from good. — Webster, 1882
Winnowing is done in the Biblical way. After the wheat has been separated from the straw, it is gathered up into a heap, and when a brisk breeze arises it is thrown into the air in the teeth of the wind, which blows away the chaff while the wheat falls by itself on the clean floor. At a distance, the flying chaff looks like steam escaping by successive puffs from the exhaust pipe of an engine. – Juneau County (Wisconsin) Argus, December 1880.
In Farmer Boy, James Wilder winnowed his beans using a fanning mill. In The Long Winter (see Chapter 3, “Fall of the Year”), Charles Ingalls tells the rest of the family that once winnowed, there should be a bushel of beans, which is a unit of dry measure equivalent to 8 gallons. To get an idea of how poor his first crop was – or perhaps even how small his bean-field was – 1880 agricultural statistics might have reported a poor crop at twelve bushels of beans per acre. Average yields for white navy beans today might be twenty to thirty bushels per acre. Remember: Charles Ingalls ended up with only ONE bushel of beans!
For such a small crop, Pa surely winnowed his beans by hand, perhaps first using a flail to break the dry husks or exocarp from the seeds (the beans) inside. The broken husks and beans could be scooped up and poured from one bucket or other vessel into another while outdoors in the wind, where the breeze would carry off the lighter husks, while gravity caused the heavier dry beans to fall.
The image at right is Jean-Francois Millet’s “The Winnower,” shows a worker with a winnowing basket, used to winnow grain such as wheat. The basket was lifted with the knee and its contents tossed and shaken, allowing the wind to carry away the chaff.
winnow (TLW 3), see also fanning mill, flail, chaff