Inch
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Inches is also an album by Les Savy Fav.{{unit of length|name= inch
m= 0.0254 | accuracy=3  | Mid-19th century tool for converting between different standards of the inch |
An inch (plural: inches; symbol or abbreviation: in or, sometimes, ″ - a double prime) 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. There are 36 inches in a yard and 12 inches in a foot. A corresponding unit of area is the square inch and a corresponding unit of volume is the cubic inch.
The inch is a common and popular unit of measurement in the United States, the United Kingdom and in Canada. In the US and the UK, personal heights are expressed in feet and inches by people of all ages. In Canada, the trend has been shifting towards metres, as shown on a person's driver's license.In 1958 the United States and countries of the Commonwealth of Nations defined the length of the international yard to be 0.9144 metres. Consequently, the international inch is defined to be equal to 25.4 millimetres.
The international standard symbol for inch is in (see ISO 31-1, Annex A). In some cases, the inch is denoted by a double prime, which is often approximated by double quotes, and the foot by a prime, which is often approximated by an apostrophe. For example, 6 feet 2 inches is denoted by 6′2″. This use can cause confusion, because the prime and double prime are international standard symbols for arcminutes and arcseconds.1 international inch is equal to:
* 1,000 thou (1 thou is 0.001 inches)
* about 0.08333 feet (1 foot is equal to 12 inches)
* about 0.02778 yards (1 yard is equal to 36 inches)
* 2.54 centimetres (1 centimetre is equal to about 0.3937 international inches)Even in countries where the use of a metric system is commonplace, the inch is used to specify the size of a:
* bicycle tyre
* television and computer display screen
* gramophone record
* diameter of pipesThe origin of the inch is disputed. Historically, in different parts of the world (even different cities within the same country) and at different points in time, the inch has referred to similar but different standard lengths.
The English word inch comes from Latin uncia meaning "one twelfth part" (in this case, one twelfth of a foot); the word ounce (one twelfth of a troy pound) has the same origin.
In some other languages, the word for "inch" is similar to or the same as the word for "thumb"; for example, French: pouce inch, pouce thumb; Italian: pollice inch, pollice thumb; Spanish: pulgada inch, pulgar thumb; Portuguese: polegada inch, polegar thumb; Swedish: tum inch, tumme thumb; Dutch: duim inch, duim thumb; Sanskrit: Angulam inch, Anguli Finger.
Given the etymology of the word "inch", it likely that the inch is a unit derived from the foot. However, some sources the inch was originally defined informally as the distance between the tip of the thumb and the first joint of the thumb.
There are records of the unit being used circa 1000 AD (both Laws of Æthelbert and Laws of Ælfred). An Anglo-Saxon unit of length was the barleycorn. After 1066, 3 barleycorn was equal to 1 inch; it is not clear which unit was the base unit and which the derived unit.
One source says that the inch was at one time defined in terms of the yard, itself supposedly defined as the distance between Henry I of England's nose and his thumb. This is unlikely as Henry was born in 1068.
Prior to the adoption of the international inch (see above), the United Kingdom and other countries of the Commonwealth of Nations defined the inch in terms of the Imperial Standard Yard. The United States and Canada each had their own, different, definition of the inch, defined in terms of metric units. The Canadian inch was defined to be equal to 25.4 millimetres.A metric inch is the equivalent of an inch under a proposal for the metrification and unification of the English system of measures. It is now considered to be a strange unit of measurement.
In Sweden, between 1855 to 1863, the existing Swedish "working inch" (24.74 mm) was replaced by a "decimal inch" (29.69 mm) which was one tenth of Swedish foot. Proponents argued that a decimal system simplifies calculations. However, having two different Swedish inch measures (and an English inch on top of that) proved to be complicated. Between 1878 to 1889 it was agreed to introduce the metric units. However, the decimal inch survived in some building construction trades, and decimal fractions (tenths, hundredths, thousandths) of the foot are still used in land surveying.*English unit
*Imperial unit
*United States customary units
*Gry
*Pyramid inch
*Guz
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