A traditional unit of volume. Sacks of different commodities are of different sizes, but a typical measure is 3 bushels (about 105.7 liters based on the U.S. bushel, or 109.1 liters based on the British Imperial bushel)
Russ Rowlett (Director), How Many? A Dictionary of Units of Measurement, Center for Mathematics and Science Education University of North Carolina, USA 2005. http://www.unc.edu/~rowlett/units/dictA.html, (Unit of Meas and Covr Factors - Amer) {608}