OK Willie, since you did that, i'll add this to help with units of measure
Oh those Brits... great sense of humor!
Gunter's Chain:
"Dimensurator or Measuring Instrument whereof the mosts usual has been the Chain, and the common length for English Measures 4 Poles, as answering indifferently to the Englishs Mile and Acre, 10 such Chains in length making a Furlong, and 10 single square Chains an Acre, so that a square Mile contains 640 square Acres." ---John Ogilby, Britannia, 1675
Gunter divided the chain into 100 links, marked off into groups of 10 by brass rings which simplified intermediate measurement. On the face of it, the dimensions make no sense: Each link is a fraction under 8 inches long; 10 links make slightly less than 6 feet, 8 inches and a full length of 66 feet.
The chain as a unit of length of 66 feet and the link, one-hundredth of a chain, probably developed as a result of the introduction of Gunter's chain as the technique of surveying; but it is important not to confuse the two; Gunter's chain is the physical device used in the field. A chain also had the commonly used subunit variously called a "rod," a "pole" or a "perch," which was 16.5 feet long, or one fourth of a chain.