Yard

This derivation of the Vitruvian Man by Leonardo da Vinci, depicts nine historical units of measurement: the Yard, the Span, the Cubit, the Flemish Ell, the English Ell, the French Ell, the Fathom, the Hand , and the Foot. The Vitruvian man was drawn to scale, so the units depicted are displayed with their proper historical ratios.

A yard (abbreviation: yd) is the name of a unit of length in a number of different systems, including English units, Imperial units, and United States customary units. Its size can vary from system to system. The most commonly used yard today is the international yard which by definition is equal to 0.9144 metre.

The yard is used as the standard unit of field length measurement in both the American, English and Canadian games of football (although Canada has officially adopted the metric system).

The yard is used on road signs and markers in the UK. Indeed, it is illegal to display length/speed in metres/kilometres on road signs in the UK, as this would cause confusion.

A "Yard" is used in both the US and Canada as a measure of volume of concrete as carried by concrete mixers, which are given a nominal rating in yards. This is shorthand for cubic yard however the word cubic is never used in this context. A typical marking would indicate that a mixer had a capacity of "11 yards" or "1.5 yards".

Yard is also a term used in financial markets for one billion units of a currency (derived from the French milliard) in order to avoid the ambiguity between "billion" and "million". E.g., a yard of dollars is $1bn, thus a buyer of a billion dollars could say "I'm a buyer of a yard of dollars."^[1]

Equivalence to other units of length

**1 yard** =
SI units
0.91440 m	914.40 mm
US customary / Imperial units
3.0000 ft	36.000 in

The early yard was divided by the binary method into two, four, eight, and sixteen parts called the half-yard, span, finger, and nail. Two yards are a fathom.

Etalons on the wall of Royal Observatory Greenwich, London, Great Britain depicting length measures - 1 yard (3 feet), 2 feet, 1 foot, 6 inches (1/2 foot), and 1 inch.

Historical origin

The yard derives its name from the word for a straight branch or rod, although the precise origin of the measure is not definitely known. Some believe it derived from the double cubit, or that it originated from cubic measure, others from its near equivalents, like the length of a stride or pace. One postulate was that the yard was derived from the girth of a person's waist, while another claim held that the measure was invented by Henry I of England as being the distance between the tip of his nose and the end of his thumb. These are believed to be more likely standardising events than a random invention of the measure. ^[2]

In currency and financial market usage, "yard" derives from "milliard", a now rarely used term for 1,000,000,000.

References

^ Bloomberg.com: Financial Glossary
^ "Money — Weights and Measures", The Every-day Book and Table Book; or, Everlasting Calendar of Popular Amusements, Sports, Pastimes, Ceremonies, Manners, Customs, and Events, Each of the Three Hundred and Sixty-Five Days, in Past and Present Times; Forming a Complete History of the Year, Months, and Seasons, and a Perpetual Key to the Almanac, Including Accounts of the Weather, Rules for Health and Conduct, Remarkable and Important Anecdotes, Facts, and Notices, in Chronology, Antiquities, Topography, Biography, Natural History, Art, Science, and General Literature; Derived from the Most Authentic Sources, and Valuable Original Communication, with Poetical Elucidations, for Daily Use and Diversion. Vol III., ed. William Hone, (London: 1838) p 378. Retrieved on 2008-06-09

Contents

Equivalence to other units of length

Historical origin

References

See also