The device, frequently seen in farmyards, by which the power of a horse is utilized to drive threshing or other machinery, is sometimes described as a "horse-power," but this term usually denotes the unit in which the performance of steam and other engines is expressed, and which is defined as the rate at which work is done when 33,000 lb are raised one foot in one minute.
The other men go back to their homes or to the factories in the cities, where they await the harvesting and threshing season.
The farmer estimates that a threshing-machine can thresh all the wheat ordinarily grown upon 2500 acres, so that a 5000-acre farmer would have at least two machines running at the same time.
Time is a very important thing in threshing, since a rainfall might spoil enough grain in one night to buy several machines.
The threshing season is thus a time of great pressure and of extensively active work.