Editing Chain (unit) (section)

==Measuring instruments==
Civil engineers and surveyors use various instruments including chains to measure distance.<ref name=Punmia_etal>{{cite book |last1=Punmia |first1=B. C. |last2=Jain |first2=A. K. |last3=Jain |first3=A. K. |year=2003 |title=Basic civil engineering |publisher=Laxmi Publications |location=New Delhi |isbn=9788170084037 |oclc=1006316184}}</ref> Other instruments used for measuring distance include tapes and bands. A steel band is also known as a "band chain".<ref>[https://theconstructor.org/surveying/types-of-chains-surveying/13889/ Types of Chains used in Surveying, Their Parts, Testing and Advantages]</ref>

===Surveyors' chain (Gunter's chain) ===
{{main|Gunter's chain}}
{{anchor|Gunter's chain}} <!-- maybe incoming redirections-->
In 1620, the polymath [[Edmund Gunter]] developed a method of accurately surveying land using a 100 link chain, 22 yards (66 feet) long, called the [[Gunter's Chain]]. [[Gunter's chain#Similar measuring chains|Other surveyors chains]] have been used historically.

=== Engineer's chain (Ramsden's chain)===
{{anchor|Ramsden's chain (engineer's chain)}}
{{main|Ramsden surveying instruments#Chains and rods}}
A longer chain of {{convert|100|ft|m|1}}, with a hundred {{convert|1|ft|mm|0}} links, was devised in the UK in the late 18th century by [[Ramsden surveying instruments|Jesse Ramsden]], though it never supplanted Gunter's chain.<ref name=Rankine>{{cite book |author1=William John Macquorn Rankine |author-link=William John Macquorn Rankine |title=A Manual of Civil Engineering |date=1863 |publisher=Griffin Bohn & Company |location=London |pages=[https://archive.org/details/amanualcivileng05rankgoog/page/n38 18]–19 |edition=2nd |url= https://archive.org/details/amanualcivileng05rankgoog}}</ref> Surveyors also sometimes used such a device, and called it the ''engineer's chain''.<!-- The term ''chain'' in this case usually refers to the measuring instrument rather than a unit of length, and distances measured are normally given in feet and decimal fractions of a foot (not inches).{{citation needed|date=July 2018}} A lot of these references refer to the manufacturing process used to increase the accuracy of an existing precision instrument- you had to solve heat expansion, twisting, and wear from friction. Also important was the design of the handle and whether it incorporated an adjustment screw. This is mainly supported by Rankine. The Rankine ref does not mention Ramsden- so thats another factoid to remove. Look to [[Anglo-French Survey (1784–1790)]] for a better reference. Indeed [[Gunter's chain#Similar measuring chains]] will be a useful starting point when it has been verified- for example Ramsden was British not American. See also:

[http://www.clintoncountyohgis.org/units_of_measure.htm Clinton is one of the many sites that copies from US government Glossary of Surveying and Mapping Terms]
[http://www.cdscapes.com/reading-property-surveys.html Charlotte dreamspace is another]-->

==={{lang|es|Vara|nocat=y}} or Texas chain===
In the [[Southwestern United States]], the ''{{lang|es|vara}} chain'' also called the ''Texas chain'', of 20 {{lang|es|[[Spanish customary units#Vara (unit of length)|varas]]}} ({{cvt|16.9164|m|ft|1}}) was used in surveying [[Viceroyalty of New Spain|Spanish]] and later [[First Mexican Republic|Mexican]] land grants, such as the major [[Fisher–Miller Land Grant|Fisher–Miller]] and [[Paisano Grant]]s in Texas, [[Land grants in New Mexico|several similarly large ones in New Mexico]], and [[Ranchos of California|over 200 smaller {{lang|es|ranchos|nocat=y}} in California]].

===Metric chains===
Metric chains, of lengths 5&nbsp;m, 10&nbsp;m, 20&nbsp;m and 30&nbsp;m, are widely used in India.<ref name=Punmia_etal /> Tolerances are ±3&nbsp;mm for 5&nbsp;m and 10&nbsp;m chains, ±5&nbsp;mm for a 20&nbsp;m chain, and ±8&nbsp;mm for a 30&nbsp;m chain.<ref>{{cite book |last=Bhavikatti |first=S. S. |year=2008 |title=Surveying and levelling |volume= 1 |publisher=IK International |location=New Delhi |isbn=9788190694209 |oclc=660131493 |chapter=Chain Surveying}}</ref>

====Revenue chain====
In India, a revenue chain with 16 links and of length {{cvt|33|ft|disp=flip}} is used in [[Cadastral surveying|cadastral surveys]].<ref>[http://www.agriinfo.in/default.aspx?page=topic&superid=8&topicid=45 Instruments used in Surveying - Instruments Used for Measuring Distance]</ref>

===Other instruments===
Also in North America, a variant of the chain is used in [[forestry]] for [[Traverse (surveying)|traverse surveys]].{{citation needed|date=July 2018}} This modern chain is a static cord (thin rope) 50 metres long, marked with a small tag at each metre, and also marked in the first metre every [[decimetre]].{{citation needed|date=July 2018}} When working in dense bush, a short [[Axe#Axes designed to cut or shape wood|axe]] or [[hatchet]] is commonly tied to the end of the chain, and thrown through the bush in the direction of the traverse.{{clarify|date=July 2018|reason=What is it called?}}

Another version used extensively in [[forestry]] and [[surveying]] is the ''hip-chain'': a small box containing a string counter, worn on the hip.{{citation needed|date=July 2018}} The user ties off the spooled string to a stake or tree and the counter tallies distance as the user walks away in a straight line. These instruments are available in both [[Foot (unit)|feet]] and [[metre]]s.