Dry gallon

The dry gallon, also known as the corn gallon, was used in the United States until recently for grain and other dry commodities. It is one eighth of the Winchester bushel, originally a cylindrical measure of 18.5 inches in diameter and 8 inches in depth. That made the dry gallon 9.25² ×π cubic inches ≈ 268.802 52 cu in. The bushel, which like dry quart and pint, still sees some use, was later defined to be 2150.42 cubic inches exactly, making its gallon exactly 268.8025 cu in (exactly 4.404 883 770 86 L). In previous centuries, there had been a corn gallon of around 271 to 272 cubic inches.

References

• "How Many? A Dictionary of Units of Measurement" by Russ Rowlett and the University of North Carolina at Chapel Hill