Linear measurement is the basis of all surveying.  No matter how accurately angles may be measured, the survey can be no more accurate than the chaining.

Old surveys were sometimes made with the surveyor's (or Gunter's) chain which was 66 ft. in length and divided into 100 links, each link 7.92 inches long.  Each link was made of iron or steel wire, and consisted of a long piece with a separate ring at each end.

The use of a chain for measuring was first recorded in 1579.  Edmund Gunter (1581-1626), an English mathematician, designed his chain to be 66 ft. long so that 10 square chains should equal one acre.  Even though it was still used into the early 1900's, the chain was heavy and clumsy, difficult to stretch tight and straight, changed its length rapidly from wear, and was at best only good for comparatively rough measurements.  In 1867, the first American patent for a steel tape was obtained.  The steel tape would eventually replace the chain altogether in the early 1900s.