This is also called a Gunter 's chain , surveyor 's chain or land chain . In 1620 , the clergyman Edmund Gunter developed a method of surveying land accurately with low technology equipment , using what became known as Gunter 's chain ; this was 66 feet long and from the practice of using his chain , the word transferred to the actual measured unit . His chain had 100 links , and the link is used as a subdivision of the chain as a unit of length .