Gallons and Cubic Inches
Date: 09/04/2001 at 11:13:26 From: Darryl Nester Subject: Volume conversion - history I know that 1 gallon is 231 cubic inches, based on the old English "wine gallon" unit. But I have not been able to find out WHY the number 231 was used. Was it simply the case that at some point in the process of standardizing volume measurements, it was determined that a wine gallon was "pretty close to" 231 cubic inches, so someone decided to use that number from then on? Or was there some deeper reason for this choice?
Date: 09/04/2001 at 16:49:29 From: Doctor Rick Subject: Re: Volume conversion - history Hi, Darryl. You can find some information on this page (under "Volume"), from the "How Many?" site by Russ Rowlett, linked from our Dr. Math FAQ: http://www.unc.edu/~rowlett/units/custom.html It doesn't say exactly how the wine gallon was defined. The following page indicates the original definition of the wine gallon: Weights & Measures 1: An American Encyclopedia http://www.todd.demon.co.uk/encyc/measures1.htm I quote: "In 1824, the British abandoned both the Ale and the Wine gallons in favour of the Imperial gallon, based on the volume of 10 pounds of water (which works out at 277.41945 cu in). America, by this time, had already standardised on the Wine Gallon of 231 cubic inches (strictly speaking, this was defined as the volume of a cylinder 6 inches long and 7 inches in diameter, or 230.9070 cubic inches)." Indeed, the volume of this cylinder is V = pi*r^2*h = 3.14159 * (7 inches/2)^2 * (6 inches) = 230.90706 cubic inches - Doctor Rick, The Math Forum http://mathforum.org/dr.math/
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