Inch
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- Inches is also an album by Les Savy Fav.
Image:Inch converter.jpg An inch is an Imperial and U.S. customary unit of length. Sweden also briefly had a "decimal inch" based on the metric system: see below for more.
According to some sources, the inch was originally defined informally as the distance between the tip of the thumb and the first joint of the thumb. Another source says that the inch was at one time defined in terms of the yard, supposedly defined as the distance between Henry I of England's nose and his thumb. In another version, the inch was defined as the length of three barleycorns. There are twelve inches in a foot, and three feet in a yard.
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.
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International inch
Template:Unit of length Historically, the inch has referred to several slightly different units of length, used in different parts of the world. There was little uniformity; different countries, and even different cities within the same country, used their own standard length. The only "inch" still in use today is the English unit. Most countries which previously had their own separate definitions of the inch, have converted to using the metric system instead. However, the inch remains a common and popular unit of measurement in the United States, the United Kingdom and in Canada, along with the mile, pound and others, despite official attempts to eradicate it. In the US and the UK, personal heights are expressed in feet and inches by people of all ages.
The international inch is defined in terms of the metric system of units to be exactly 25.4 mm. This definition was agreed upon by the U.S. and countries of the Commonwealth of Nations in 1958. Prior to that, the U.S. and Canada each had their own, slightly different, definition of the inch in terms of metric units, while the UK and other Commonwealth countries defined the inch in terms of the Imperial Standard Yard. The definition adopted was the Canadian definition. A metric inch was also used in some Soviet clones of Western computers. The clones were a slightly scaled-down copy, and hence Soviet parts did not match exactly with Western ones.
Even in generally metric countries, the inch is used for various purposes, such as the sizes of bicycle tires or television and computer screens.
The thou
The thou or mil is a unit sometimes used in engineering equivalent to one-thousandth of an international inch, and thus defined to be 25.4 µm. Use of the thou is now generally deprecated in favour of the use of SI units. When "thou" is the measurement, its "th" is pronounced as in "thousand" — IPA Template:IPA — and not as in "that" or the pronoun "thou" — IPA Template:IPA.
Notation
The international standard symbol for inch is in (see ISO 31-1, Annex A). In some areas, the unit inch is also denoted by a double prime (ex. 30″ = 30 in), often approximated by a quotation mark. Similarly, feet can be denoted by a prime (often approximated by an apostrophe), and then 6′2″ means 6 feet plus 2 inches. However, since the prime and double prime are the international standard symbols for arcminutes and arcseconds, this can, in certain contexts, cause confusion.
Sweden
In the 19th century, Sweden devised a way into the metric world. First, in 1855–1863 the existing "working inch" was changed into a "decimal inch" which was 1/10th foot or approximately 0.03 metres. Proponents argued that a decimal system simplifies calculations, but having two different inch measures turned out to be so complicated that in 1878–1889 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.
See also
External links
- Length Converter
- Inch Conversion table
- Conversion of length: Inches and feet to centimetres and metresbg:Инч
ca:Polzada da:Tomme de:Zoll (Einheit) eo:Colo es:Pulgada et:Toll (pikkusühik) fa:اینچ fr:Pouce (unité) he:אינץ' hu:Hüvelyk_(mértékegység) ja:インチ la:uncia ms:Inci nl:Inch no:Tomme pl:Cal (jednostka) pt:Polegada ro:Inch ru:Дюйм simple:Inch sl:Palec sv:Tum uk:Дюйм zh:英寸