Dry gallon

The dry gallon, also known as the corn gallon or grain gallon, is a historic British dry measure of volume that was used to measure grain and other dry commodities and whose earliest recorded official definition, in 1303, was the volume of 8 pounds of wheat.[1] It is not used in the US customary system – though it implicitly exists since the US dry measures of bushel, peck, quart, and pint are still used – and is not included in the handbook that many states recognize as the authority on measurement law.[2][3]

The fluid gallon is another volume measure of approximately the same size, though the dry gallon is a bit bigger. 1 dry gallon ≈ 1.163 647 fluid gallons

Its implicit value in the US system was originally one eighth of the Winchester bushel, which was a cylindrical measure of 18.5 inches in diameter and 8 inches in depth. That made the dry gallon a non-terminating number of cubic inches, an irrational number whose value with the first six digits after the decimal point was 268.802521 (9.252 × π cubic inches ≈ 268.802521 in3). The bushel was later defined to be exactly 2150.42 cubic inches, making the dry gallon exactly 268.8025 in3 (exactly 4.40488377086 L).

References

  1. ↑ "How Many? A Dictionary of Units of Measurement" by Russ Rowlett and the University of North Carolina at Chapel Hill
  2. ↑ 101st Conference on Weights and Measures 2016. (2017). Specifications, Tolerances, and Other Technical Requirements for Weighing and Measuring Devices. National Institute of Standards and Technology. p. C-6, C-11, C-16.
  3. ↑ Summary of State Laws and Regulations in Weights and Measures Archived December 5, 2011, at the Wayback Machine.. (2005) National Institute of Standards and Technology.


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