Gunter's chain

A surveyor's chain, also known as a Gunter's chain, is an instrument used to measure the length of fields and agricultural land. It consists of several units (short metal bars) of the same length that are joined together at each end with two rings or links, and either end of the chain has a handle that is also made of metal. A nail would be put through a link to secure the chain in the ground, allowing the surveyor to measure the land, which would match the point at the center of the chain. These chains were used in surveying classes. This chain in particular was used by a schoolteacher called Moisés Jiménez when he took students from the school of Berdún in Huesca on day trips to the countryside. Only boys studied this subject.