Land Surveyor's Chain - The ordinary Gunter's or surveyor's chain is sixty-six feet or four poles long, and is composed of one hundred links, connected each to each by two rings, and furnished with a tally mark at the end of every ten links.  A link in measurement includes a ring at each end, and is seven and ninety two one hundredths inches long.  In all the chains which we make the rings are oval and are sawed and well closed, the ends of the wore forming the hook being also filed and bent close to the link, to avoid kinking.  The oval rings are about one third stronger than round ones.  [Source]

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