Chain

Chain, in Surveying, is an appliance for measuring lengths, introduced by Gunter. It is composed of 100 links of iron or steel, each 7.92 inches long, and making a total length of 22 yards. In very accurate work allowance is made for expansion due to increase of temperature. Ten square chains, or 100,000 square links, make one acre. Areas may often be accurately surveyed by use of the chain only; this dispenses with any measurement of angles by dividing the area into well-shaped triangles, each of which is determined by the lengths of its sides. Irregularities of the boundary, etc., are measured by offsets.