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English units refers to the historical units of measurement in medieval England, which evolved as a combination of the Anglo-Saxon and Roman systems of units. They were superseded in England in 1824 by the Imperial system, which retained many but not all of the unit names, and further superseeded in the 1970s by the SI subset of the Metric system.

Within the United States, the same term is commonly used to refer to the United States Customary System¹, which retains some unit names but with different values, but this term is generally considered to be ambiguous outside the United States.

Various standards under the name English units have applied at different times, in different places and for different things. Prior to the Battle of Hastings in 1066 the Anglo-Saxon system of measurement had been based on the units of the barleycorn and the gyrd (rod), inherited from tribes from Germany. After the Norman conquest, Roman units were reintroduced. The resultant system of English units was a combination of the Anglo-Saxon and Roman systems.

Later development of the English system continued by defining the units by law in the Magna Carta of 1215, and issuing measurement standards from the then capital Winchester. Standards were renewed in 1496, 1588 and 1758. The last Imperial Standard Yard in bronze was made in 1845; it served as the standard in the United Kingdom until the yard was internationally redefined as 0.9144 metre in 1959 (statutory implementation: Weights and Measures Act of 1963). The English system then spread to other parts of the British Empire.

Length

Chart showing the relationships of distance measures.

poppyseed 

¹⁄₄ of a barleycorn^{citation needed}

barleycorn 

Basic Anglo-Saxon unit, the length of a corn of barley. The unit survived after 1066, redefined as ¹⁄₃ inch. Note the relation to the grain unit of weight.

digit 

³⁄₄ inch

finger 

⁷⁄₈ inch

hand 

4 inches

ynch, inch 

Anglo Saxon inch, 3 barleycorns. Based on the Roman uncia from 1066.

nail 

3 digits = 2+¹⁄₄ inches = ¹⁄₁₆ yard

palm 

3 inches

shaftment 

Width of the hand and outstretched thumb, 6+¹⁄₂ ynches before 1066, 6 inches thereafter

span 

Width of the outstretched hand, from the tip of the thumb to the tip of the little finger, 3 palms = 9 inches

foot 

Usually 13 inches but also other variants. Shortened to 12 inches by basing it on the Roman pes from 1066.

cubit 

Forearm, 18 inches.

yard 

Introduced after 1066, 3 feet = 36 inches.

ell 

Elbow, 20 nails = 1+¹⁄₄ yard or 45 inches. Mostly for measuring clothing

fathom 

From one fingertip on one hand to the other finger tip on the other hand, 6 feet

rod 

Saxon gyrd measuring stick, might have been from 20 "natural feet". Retained its length but redefined as 16+¹⁄₂ feet after 1066.

chain 

four linear rods. Named after the length of surveyor's chain used to measure distances until quite recently. Any of several actual chains used for land surveying and divided in links. Gunter's chain, introduced in the 17th century, is 66 feet.

furlong 

"One plough's furrow long" (Saxon furrow is furh), the distance a plough team could be driven without rest. This varied from region to region depending on soil type and local habit. In modern context, it is deemed to be 660 feet, 40 rods or ten chains.

mile 

Introduced after 1066, originally the Roman mile at 5000 feet, in 1592 it was extended to 5280 feet to make it an even number (8) of furlongs.

league 

Usually three miles. Intended to be an hour's walk.

Area

perch

one rod, when referring to length; one square rod when referring to area; one rod by one foot by a foot and a half when referring to volume (usually specifically for masonry stonework)

acre

area of land one chain (four rods) in width by one furlong in length. As the traditional furlong could vary in length from country to country, so did the acre. In England an acre was 4,840 square yards, in Scotland 6,150 square yards and in Ireland 7,840 square yards. It is a Saxon unit, meaning field. Probably meant to be "as much area as could be plowed in one day".

rood

one quarter of an acre, confusingly sometimes called an acre itself in many ancient contexts. One furlong in length by one rod in width, or 40 square rods.

carucate

an area equal to that which can be ploughed by one eight-oxen team in a single year (also called a plough or carve). Approximately 120 roods.

bovate

the amount of land one ox can plough in a single year (also called an oxgate). Approximately 15 roods or one eighth of a carucate.

virgate

the amount of land a pair of oxen can plough in a single year. Approximately 30 roods (also called yard land).

Administrative units

hide

four to eight bovates. A unit of yield, rather than area, it measured the amount of land able to support a single household for agricultural and taxation purposes.

knight's fee

five hides. A knight's fee was expected to produce one fully equipped soldier for a knight's retinue in times of war.

hundred

or wapentake - 100 hides grouped for administrative purposes.

Volume

General

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In both the United Kingdom and America, in addition to perch as a measure of length, there is also the perch which refers to the volume measurement of stone; one perch is equal to 16.5 ft × 1.5 ft × 1 ft = 24.75 cu. ft. of dry stone. The relationship to the unit of length (one perch = 16.5 feet) should be obvious.

Units of volume included:

Mouthful

about ¹⁄₂ Ounce

Jigger

Mouthful × 2 = 1 oz.

Jack or Jackpot

Jigger × 2 = 2 oz.

Gill

Jack × 2 = 4 oz (U.S.) or 5 oz (imperial).

Cup

Gill × 2 = 8 oz.

Pint 

Cup × 2 = 16 oz. (U.S.) or 20 oz (imperial) (and a "Pint's a pound the world around" or in the United Kingdom, "A pint of pure water weighs a pound and a quarter")

Chart showing the relationships of volume measures.

Quart

Pint × 2 = 32 oz. (U.S.) or 40 oz (imperial)

Pottle or Half Gallon

Quart × 2 = 64 oz. (U.S.) or 80 oz (imperial)

Gallon

Pottle × 2 = 4 Quarts = 128 oz. (U.S.) or 160 oz (imperial)

Peck

Gallon × 2

Kenning

Peck × 2 = 4 gal.

Bushel

Kenning × 2 = 8 gal.

Cask, Strike, or Coomb

Bushel × 2 = 16 gal.

Barrel

Cask × 2 = 32 gal.

Hogshead 

Barrel × 2 = 64 gal.

Butt or Pipe

hogshead × 2 = 128 gal.

Tun 

Butt × 2 = 256 gal. (A tun is a ton)

A Tun would actually be about 2,048 lb. but is a pretty close estimate, given that you would derive the weight and volume all from mouthfuls of water.

Wine

Brewery

Weight

Chart showing the relationships of weight measures.

The Avoirdupois, Troy and Apothecary systems of weights all shared the same finest unit, the grain, however they differ as to the number of grains there are in a dram, ounce and pound. Originally, this grain was the weight of a grain seed from the middle of an ear of barley. There also was a smaller wheat grain, said to be ³⁄₄ (barley) grains or about 48.6 milligrams.

Avoirdupois

Main article: Avoirdupois

grain (gr) 

64.79891 mg, ¹⁄₇₀₀₀ of a pound

dram/drachm (dr) 

27.34375 gr (sixteenth of an ounce) (possibly originated as the weight of silver in Ancient Greek coin drachma)

ounce (oz) 

16 dr = 437.5 grains ≈ 28 g

pound (lb) 

16 oz = 7000 grains ≈ 454 g (NB: 'lb' stands for libra)

quarter 

¹⁄₄ cwt

hundredweight (cwt) 

112 lb (long) or 100 lb (short)

ton 

20 cwt

Additions:

nail 

¹⁄₁₆ cwt = 7 lb

clove 

7 lb (wool) or 8 lb (cheese)

stone (st) 

2 cloves = 14 lb (an Anglo-Saxon unit changed to fit in)

tod 

2 st = ¹⁄₄ cwt (long)

Troy and Tower

The Troy and Tower pounds and their subdivisions were used for coins and precious metals. The Tower pound, which is based upon an earlier Anglo-Saxon pound, was abolished in 1527.

In terms of (silver) currency a pound was 20 shillings of 12 pennies each (i.e. 240) from the late 8th century (Charlemagne/Offa of Mercia) to 1971 in the United Kingdom, but lighter than a troy one. Most old European currencies, like mark, shilling/solidus/groschen/øre, penny/pfennig/denar, taler/dollar/krone, florin/gulden/guilder/pound/złoty also belong into this monetary system.

Troy

grain (gr) 

≈ 65 mg

pennyweight (dwt) 

24 gr ≈ 1.56 g

ounce (oz t) 

20 dwt = 480 gr ≈ 31.1 g

pound (lb t) 

12 oz t = 5760 gr ≈ 373 g

mark

8 oz t

Tower

tower ounce 

18+³⁄₄ dwt = 450 gr ≈ 29 g

tower pound 

12 oz T = 225 dwt = 5400 gr ≈ 350 g

Apothecary

grain (gr) 

≈ 65 mg

scruple (s ap) 

20 gr

dram (dr ap) 

3 s ap = 60 gr

ounce (oz ap) 

8 dr ap = 480 gr

pound (lb ap) 

5760 gr = 1 lb t

Others

Merchants/Mercantile pound 

15 oz tower = 6750 gr ≈ 437.4 g

London/Mercantile pound 

15 oz troy = 16 oz tower = 7200 gr ≈ 466.6 g

Mercantile stone 

12 lb L ≈ 5.6 kg

Butcher's stone 

8 lb ≈ 3.63 kg

Sack 

26 st = 364 lb ≈ 165 kg

The carat was once specified as four grains in the English-speaking world. Some local units in the English dominion were (re-)defined in simple terms of English units, such as the Indian tola of 180 grains.

See also

• Obsolete Scottish units of measurement
• slug and poundal

See also

• Feudalism
• Domesday Book
• Weights and measures
• History of measurement
• Comparison of the imperial and US customary measurement systems
• Plan for Establishing Uniformity in the Coinage, Weights, and Measures of the United States
• Approximate conversion of units
• Metrication
• Winchester measure
• Imperial units

References

1. ^ Marks' Standard Handbook for Mechanical Engineers, McGraw Hill, 2006

External links

• English Customary Weights and Measures
• Jacques J. Proot's Anglo-Saxon weights & measures page.
• Alexander Justice, "A General Discourse of the Weights and Measures" (London, 1707).

Wikipedia content modification information:

• This page was last modified on 11 December 2008, at 05:03.

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