I have been researching US non-metric definitions.
Handbook 130 says a US gallon is 231 cubic inches. http://ts.nist.gov/ts/htdocs/230/235/h130-03/07_IV_PackLabReg.pdf
Federal standard 376 says it is 3.785412 liters http://ts.nist.gov/ts/htdocs/200/202/fs376-b.pdf
There is a small difference between the two values. Is the US gallon precisely defined in terms of cubic inches or liters?
In USMA 25048 Terry Simpson wrote:
>AFAIK, the US gallon is precisely defined as 5/6 imperial gallon, and>the imperial gallon is exactly 10 pounds of water (presumably at 4C).
In 1896 the (US) Committee on Weights and Measures reported that the Treasury Department by formal order had adopted the metric standards as the "fundamental standards" from which the measures of the customary should be derived. This led to the definition that: 1 meter = 39.37 inches.
The US gallon had always been 231 cubic inches, This now became
231 cubic inches = 3.785 434 497 LIn 1959, by agreement of a confernce if English-speaking countries,
1 inch = 25.4 mm,
and hence 1 US gallon = 231 cubic inches
= 3.785 411 784 LSince Federal Standard 376 says 1 gallon = 3.785412, it would appear that the US gallon has shrunk, along with the other American measures, by 0.0006%. So far as I am aware, there has been no protest at this reduction.
The imperial gallon is defined as the volume of 10 avoirdupois pounds of water at 62�F.
-- Joseph B. Reid 17 Glebe Road West Toronto M5P 1C8 Telephone 416-486-6071
