A link, also called a Gunter’s link, was a unit of length in the imperial and US customary systems. Links were commonly used in measuring land in the English-speaking world before the twentieth century, but are never used. "Link" is abbreviated as "ln". It was invented by Edmund Gunter, a professor of astronomy at Gresham College, London, the same man who made the chain. He made the link as a low-technology piece of equipment that could survey small areas of land very accurately, whereas the chain could measure towns and large areas of land.