Last updated : Mar. 20, 2006
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Actually, the usual happened : the foot and the rod went slowly their separate ways, being used by different industries (the weaver and the farmer ...) Things had to be straightened up and, as the foot and the rod were already entrenched, we find these strange figures : 16.5 ft/rod and 5280 ft/mile. This was voted by the House under Queen Elizabeth I in 1595.
It should be noted that the furlong comes from the Greek and Roman stadion, which they themselves inherited from more ancient times. It seems to be the optimal length for the traditional plough.
Sometimes we'll find a Scottish Mile (= 5940 feet) and an Irish Mile (= 6720 feet).
The rod was determined by lining up 16 men (after the Sunday Service, the story goes) and measuring the combined lenght of all their left feet. These 16 feet make up 16.5 "feet". Thickness of the shoes ? Gaps between feet ? This is tradition ...
Another old British unit was the rope equal to 20 feet.
We may also mention the wrap (= 12 ropes) and the lea (= 18 ropes) often confused with a league.
"Nautical" units :
There is also a Geographical Mile defined as 1 minute of arc along the Equator and equal to 6087.2 feet - or 1855.378 meters.
About cable length, I received an E-mail from Ralph Zimmermann stating : "You list a cable as being 720 feet, which is accurate if you are talking about depth in water. A cable refering to a distance across water is defined as 1/10th of a Nautical Mile". I rushed to my old Encyclopaedia Britannica and it confirmed : "the old usage whereby the length of a hempen anchor cable was 101 fathoms survives in the British naval measurement of a 'cable length' or one-tenth of a nautical mile".
Other length units :
Note : The first attempts to standardize the measures in England can be traced to the Magna Carta (1215). At about this time, the "Iron Yard of our Lord the King" was prescribed, subdivided into 3 feet, each 12 inches long. Three barley corns made one inch. Another story tells that Henry I standardized the yard by the length of his own arm (from his nose). Sets of standards for length and weight, generally in bronze, were sent from the capital - Winchester originally - to the main cities. In 1496, discrepancies had crept in and, following a Parliamentary inquiry, new standards were made. The same happened again in 1588, under Elizabeth I, and again in 1758. The last one, the Imperial Standard Yard in bronze was manufactured in 1845 after the previous standard had been destroyed in the fire that burned down the House of Parliament in 1834.
Copies of this yard were sent to the US and were found to be 0.0024 % shorter than the yard used so far (which was named the Troughton's scale - received in 1814 from London.)
Actually, this continuous effort to standardize the units warranted the survival of the system to this day. In "metricated" countries like Canada, it is still used partly as an old habbit but also, let's recognize it, because a pound of potatoes looks cheaper than a kilo and a square foot of carpet cheaper than a square meter !
In 1893, in the US, the yard was defined as 3600 / 3937 meter. One inch was therefore equal to 25.40005 mm while in England it was 25.39998 mm according to the Imperial Standard.
In 1959, all Anglo-Saxon countries decided that a yard would be 0.9144 meter exactly. The ancient yard (and foot) used in geodesic surveys is called the survey yard and the new one is the international yard. Since this change, one international inch is equal to 25.4 mm without further decimals.
All equivalencies in this chapter are based on the International inch - just keep in mind its changing value when you encounter old units.
(Rem : in South Africa, the Cape foot was 0.314858 meter -- used until 1950)
A unit of Spanish origin widely used in the South of the United States is the vara, equal to 33 1/3 inches (but slightly different in Mexico and even more further South.) In theory, 5000 varas will make a legua. See also under "area".
In England, the Winchester standards were used since the 15th Century. They were slowly modified, as usual : at the beginning of the 18th Century, we had a wine gallon containing 231 cubic inches, an ale gallon of 282 cubic inches and even a corn ("Winchester") gallon. The bushel was defined at a time as "any round measure with a plain and even bottom, being 18.5 inches wide throughout and 8 inches deep" (hence its official US definition : 2150.42 cu.in.)
At the same time in the US, the old wine gallon (also called Queen Anne's gallon) just discarded in England became the new official US Gallon (= 3.785411784 liter).
At least in England, they had a common system for liquid and dry measures thereafter.
Note : not all units are used in all three systems and the cup is rather recent.
The Weights and Measures Act of 1824 defined an Imperial British Gallon to replace all others : it was to contain 10 pounds of pure water at 62°F (inspired by the decimal system ?) (= 4.54609 liters).
In the US, there are two systems : for liquid measures, the base is the US Gallon just mentioned. The dry measures are based on the old Winchester Gallon (= 4.404884 liter) or 268.8025 cubic inches. I won't calculate each equivalent in the three systems, I am sure the interested reader would like to enjoy it all alone.
In the US, beware the heaped bushel !
The (latest) measures being based on the Imperial Gallon, the equivalencies are obvious.
But in the US, 1 quart (US) = 32 fl. ounces ! A US fl. ounce is equal to 29.5735 ml.
Pound history : see under "Troy"
The flask is still used, essentially as the selling unit for mercury = 76 pounds (Avoirdupois) or 34.473 kg in UK - but 75 pounds in the US !
Let's mention a unit I love : the kip or kilopond (= 1000 lbs, of course, but generally used as a unit of force.) -- Beware : in the US, it is used sometimes as "kilogram-force" ! Just what we needed to simplify the system.
Other old English units :
Avoirdupois in French means "to have weight" or "goods of weight" by extension
- used for commercial operations.
There are several other units (pack, pig, tierce, bag, bale, cask, fodder, ...) but quite often they mean different weights according to the material being measured. Call if you have a specific question.
Troy weight
Another meaning of carat or karat is the analysis of precious metals as alloys, in twenty-four parts.
Example : a 22 carat gold contains 22/24 gold or 91.7 %, the remaining being generally silver.
Note : in England, the Troy pound was abolished on Jan. 6, 1879.
Only the Troy ounce and its subdivisions were retained.
Detail : The name Troy, used for weighing precious metals, is derived from the city of Troyes (Champagne - France) where the system is thought to have originated : they had a well known commercial fair throughout the Middle Ages.
Anecdote : the pennyweight was also defined in 1266 by Henry III as the weight of 32 wheatcorns taken in the middle of the ear. NB : for 24 grains, what species ? :-)
In monetary terms, a Troy pound of silver gave its name to the Sterling pound, subdivided into 20 shillings or 240 pence (pennyweights).
Historically the pound derives from the Roman libra (hence the abbreviation "lb") whose weight was anything between 4944 and 5220 grains.
("Libra" meant a weight or a balance - it survives in the expression "equal weights" - equilibrium).
It was subdivided into 12 unciae or ounces.
NB : the abbreviation "oz" seems to have come from the Italian "onza" - meaning ounce, of course.
The oldest standard in England, the Saxon pound, became known as the Tower pound because it was kept in the Tower of London and weighed 5400 grains. Henry VIII replaced it with the Troy pound in 1527, ordering that an ounce be 480 grains and not any more 450 grains. (The "pounde Troye which exceedeth the pounde Tower in weight iii quarters of the oz." Meaning that the difference between the two pounds was 360 grains or 3/4 of a new ounce.) He made the new Troy pound the official standard for minting coins.
Note : no surprise, a heavier mint reference means more taxes !
Over the centuries the old Saxon pound had been used in parallel with a variety of foreign pounds (french, it seems) in everyday business. The most successful one - avoirdupois - was "assimilated" as having 15 Troy ounces of today (16 Troy oz of that time), therefore 7200 grains. Henry VIII brought it down to 7000 grains to be divided into 16 "special" ounces and later Elizabeth I prohibited all other "merchant" pounds.
Note : in France, the merchant pounds were often already divided into 16 ounces.
In Paris, 1 once had 576 grains but the grain was lighter (about 53.1 mg vs 64.8 mg for the English grain).
It should be noted that this once was very close to the Troy ounce : only 1.7 % difference.
Standards were kept in the House of Parliament and shared their history with the length units (destroyed by fire in 1834 - new standards from preserved copies in 1845.)
The US pound has always been more or less similar to the avoirdupois pound. In 1830, the Senate ordered an inspection in the customhouses and uncovered quite a variety of "standards". In the following years, new standards were dispatched to the customhouses and to the governor of each state, based on 7000 / 5760 of the new Troy pound received recently and adopted in 1828 as the official Mint reference.
The US pound is officially defined as a fraction of the kilogram since 1889.
On July 1, 1959, all English speaking countries decided to average off their differences and adopt an Avoidupois pound weighing exactly 453.59237 g. (There was actually very little change, but in the last couple of decimals.)
Other old units :
Apothecaries weight
Based on the Troy system
The old printers decided to allocate 12 points to the height of a standard PICA.
A point is 13.837 mils or 351.4598 microns. We find the following names :
Cloth measures
Raw cotton
Packed in bales so named because cotton was baled or tied into big bundles.
As always with old units used all over the world, there is quite an array of values. A long time ago, we could find bales of 250 lbs in Brasil and Peru, in India 400 lbs and in Egypt 740 lbs ...
In the United States, a bale of cotton was supposed to weigh 500 lbs exactly according to a Cotton Futures Act (Number 39) but it didn't seem to be widely respected - quite tempting to pack in smaller units, isn't it ?
According to the Encyclopaedia Britannica (1967), the bales average 490 lbs net in the States and 478 lbs in other countries.
Fabric measures - cotton
Under perpetual construction. I enjoy it ! Please come back from time to time.
Last updated : Mar. 20, 2006
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