CHAIN, in surveying, is a measure consisting of a certain number of links of iron wire, usually a hundred, and serving to take the dimensions of fields, &c. This is what Mersenne takes to be the arpipendium of the ancients.
The chain is of various dimensions, as the length or the number of links varies: that commonly used in measuring land, called Gunter's chain, is in length four poles or perches; or sixty-six feet, or a hundred links, each link being seven inches ; and hence it is easy to reduce any number of these links to feet, or any number of feet to links.