This might give some more information about the differences between proper measurements and the new-fangled American system.
The imperial gallon was originally defined as the volume of 10
avoirdupois pounds of water under specified conditions. The imperial
gallon (4.54609
litres is 20% larger than the United States liquid gallon (3.785411784 L). The imperial
bushel (36.36872 L) is 8 imperial gallons and is about 3% larger than the US bushel (35.23907016688 L).
The subdivision of the imperial gallon in British
apothecaries' fluid measure differed in two important respects from the corresponding United States subdivision: the imperial gallon was divided into 160
fluid ounces, the United States gallon into 128 fluid ounces; and a "
fluid scruple" is included (one third of a fluid dram).
These differences come from the various systems that were in use in Britain when the first colonies in North America were established. The American colonists adopted the English
wine gallon of 231 cubic inches (3.78541178 litres), and used it for all fluid purposes. Obviously the New Americans liked Wine. The English of that period used this wine gallon, but they also had the ale gallon of 282 cubic inches (4.62115205 litres). In 1824, the British adopted the British imperial gallon, defined as the volume of 10
pounds of water at a temperature of 62
°F, weighed in air with brass weights, by calculation equivalent to about 277.42 cubic inches (4.5461 L)—much closer to the ale gallon than the wine gallon. So it seems that the British had a preference for ale rather than wine. At the same time, they redefined the bushel to be 8 gallons. I think that I am partially Americanised as I like both Ale and Wine in whatever measurements are available.
Even under the new imperial system,
wine volumes continued to be measured in the old 231-cubic-inch wine gallons (3.78541178 litres) for tax purposes, and this practice continued until the late 1990s.
As noted above, in the imperial British system the units of
dry measure are the same as those of liquid measure. In the United States these two are different: the gallon and its subdivisions are used in the measurement of liquids, the bushel and its subdivisions in the measurement of certain dry commodities. The US gallon (3.785411784 L) is divided into four liquid
quarts (946.352946 mL each) and the US bushel (35.23907016688 L) into 32 dry quarts (1.101220942715 L) or 4
pecks (8.80976754172 L). All these units of volume for liquid measures are about 20% larger in the imperial system than in the US system. However, the British fluid ounce is only about 96% of the US fluid ounce because there are 40 fluid ounces in the British quart but only 32 fluid ounces in the US quart.
In the imperial system an avoirdupois ounce of water at 62 °F (16.67 °C) has a volume of one fluid ounce, because 10 pounds is equivalent to 160 avoirdupois ounces and 1 imperial gallon is equivalent to 4 imperial quarts, or 8 pints. This convenient fluid-ounce-to-avoirdupois-ounce relation does not exist in the US system because a US gallon of water at 62 °F weighs about 8 1⁄3 pounds, or 133 1⁄3 avoirdupois ounces, and the US gallon is equivalent to 128 fluid ounces.
In the apothecary system of liquid measure the British add a unit, the fluid scruple, equal to one third of a
fluid dram between their
minim and their fluid dram.
One noticeable comparison between the imperial system and the US system is between some Canadian and American beer bottles. Many Canadian brewers package beer in an 12-imperial-fluid-ounce bottles, which are 341 mL each. American brewers package their beer in 12-US-fluid-ounce bottle, which are 355 mL each. This results in the Canadian bottles being labelled as 11.5 fl.oz in US units when imported into the United States.
So there we have it ... The Americans might have bigger Prairies than the UK , but we've got bigger gallons.
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