Spare a thought for all the old apprentice serveyers that had to lug the chain up and down the hill 3 times to ensure the measurements were right. They all probably wished they were measuring knots on a boat by the time the 2nd time down the hill startedDed Driver said:maybe getting a bit off subject, but for interest;
The chain is a unit of length equal to 66 feet (22 yards). It is subdivided into 100 links or 4 rods. There are 10 chains in a furlong, and 80 chains in one statute mile. ... These longer chains became obsolete following the adoption of the imperial system in 1824.
https://en.wikipedia.org/wiki/Chain_(unit)