chain | |
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The chain is based on the length of Gunter's chain, which is 66 feet (22 yd) long. | |
General information | |
Unit system | Imperial/US units |
Unit of | length |
Symbol | ch |
Conversions | |
1 ch in ... | ... is equal to ... |
Imperial/US units | 22 yd, 66 ft, 100 links |
Metric (SI) units | 20.1168 m |
The chain (abbreviated ch) is a unit of length equal to 66 feet (22 yards), used in both the US customary and Imperial unit systems. It is subdivided into 100 links.[1][2] There are 10 chains in a furlong, and 80 chains in one statute mile.[2] In metric terms, it is 20.1168 m long.[2] By extension, chainage (running distance) is the distance along a curved or straight survey line from a fixed commencing point, as given by an odometer.
The chain has been used for several centuries in England and in some other countries influenced by English practice. In the United Kingdom, there were 80 chains to the mile, but until the early nineteenth century the Scottish and Irish customary miles were longer than the statute mile; consequently a Scots chain was about 74 (imperial) feet,[3] an Irish chain 84 feet. These longer chains became obsolete following the adoption of the imperial system of units in 1824.[4]
In India, "metric chains" of exactly 20 metres (65.62 feet) are used, along with fractions thereof.[5]
Since the foregoing Report [on the best route for the Forth and Clyde Canal] ... was delivered ... , Mr Smeaton has discovered that, notwithstanding the care and pains he took to be correct, he has committed an error, in supposing the Scotch chain, with which the measures of the length of the tract of land were taken, to consist of seventy feet each, whereas, in reality, it consists of seventy-four
Punmia_etal
was invoked but never defined (see the help page).