This section is from the book "Spons' Mechanics' Own Book: A Manual For Handicraftsmen And Amateurs", by Edward Spon. Also available from Amazon: Spons' Mechanics' Own Book.
In measuring standing limber, the length is taken as high as the tree will measure 24 in. in circumference. At half this height the measurement for the mean girth of the timber in the stem of the tree is taken. One-fourth this girth is assumed to be the side of the equivalent square area. The buyer has generally the option of choosing any spot between the butt-end and the half height of the stem as the girding place. All branches, as far as they measure 24 in. in girth, are measured in with the tree as timber.