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Subject: RE: [FlyRotary] Re: Fuel - Weights and Measures
Date: Fri, 29 Sep 2006 16:18:11 -0400
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More history of measurements ... extracted from:
http://home.att.net/~numericana/answer/units.htm#gallon

The US gallon, the so-called Winchester gallon, is now defined as =
exactly
equal to 231 cubic inches (this odd value comes from rounding up the =
volume
of a cylindrical measure 7 inches in diameter and 6 inches in height, =
which
dates back to the days of the Magna Carta).  Since 1959, the inch is =
exactly
25.4 mm. This means that there are exactly 3785.411784 ml in a US =
gallon.=20

If the British Gallon is meant, the answer is 4546.09 ml, also an exact
value according to the 1985 British "Weights and Measures Act" (in 1963, =
the
British Parliament had decided to redefine all British units in metric
terms).  There are about 277.42 cubic inches in this so-called Imperial
gallon.=20

Originally (in 1819), the Imperial gallon was meant to be the volume
occupied by 10 pounds of water at 62=B0F.  It's intermediate in value =
between
the two British units it replaced in 1824, namely the corn gallon of =
272=BC
cubic inches (4461.378174 ml) and the ale gallon of 282 cubic inches
(4621.152048 ml).  The old British wine gallon of 231 cu in survives as =
the
US gallon (see above)

Henry VII [Tudor] reigned from 1485 to 1509.  In 1495, the Winchester =
bushel
was legally defined as the capacity of actual standard bushels bearing =
his
seal and kept at the Exchequer.  In 1696, these were measured to be =
about
2145.6 cubic inches, under the supervision of members of the British =
House
of Commons who were discussing some excise duty on malt.  It was then
suggested that the bushel itself be defined as a simple circular measure
roughly equivalent to this.=20

This was enacted in 1701 (during the reign of William III of Orange)  =
when
the Winchester bushel was legally redefined, under the name of corn =
bushel,
as the capacity of "any round measure with a plain and even bottom, =
being
18=BD inches wide throughout and 8 inches deep" (there would have been =
exactly
100 of these in the above container).  This volume was later rounded =
from
2150.420171... down to exactly 2150.42 cubic inches, which is how the
so-called malt bushel has been normally defined since at least 1795.  =
(We
couldn't determine the exact point at which the older cylindrical =
definition
of this bushel faded from view.  Please, tell us whatever you may know.
Thanks.)=20

The same thing happened to the US gallon, which is a descendant of the =
old
Winchester wine gallon, a cylindrical measure from the days of the Magna
Carta: 7" in diameter and 6" deep, or about 230.90706 cubic inches.  =
This
capacity was statutorily rounded to 231 cubic inches in 1707, under the
reign of Anne Stuart  (it was thus once known as the Queen Anne wine
gallon).=20

Both Winchester units are thus tied to the inch and have, in effect, =
been
redefined every time the inch was.  The current units of capacity are =
based
on the 1959 international inch, which is now forever defined in metric =
terms
(1" =3D 25.4 mm).=20

The US adopted the Winchester system for capacities in 1836, using the =
above
equivalences. The British had adopted the competing Imperial system in =
1824,
on the totally different basis of an Imperial gallon then introduced as =
the
volume occupied by 10 lb of water at 62=B0F  (later redefined in metric =
terms,
as exactly equal to 4.54609 L)  and an Imperial bushel equal to 8 of =
these
gallons.