Chain (unit)
Edmund Gunter, a clergyman and mathematician, invented a measuring device called a chain. The chain was  long. It was divided by 100 in small metal links. The links were made of thick wire with a loop at each end. The links were connected to each other by three rings. There were brass handles at each end. People folded the chain up, link by link, and carried it in their hand. The name chain comes from these devices.