Fig. 3. Back of Tongue of Steel Square, Showing Brace Measure.
Fig. 4. Back of Blade of Steel Square, Showing Essex Board Measure.
On the back of the blade ([Fig. 4]) will be found the board measure, where eight parallel lines running along the length of the blade are shown and divided at every inch by cross-lines. Under 12, on the outer edge of the blade, will be found the various lengths of the boards, as 8, 9, 10, 11, 12, etc. For example, take a board 14 feet long and 9 inches wide. To find the contents, look under 12, and find 14; then follow this space along to the cross-line under 9, the width of the board; and here is found 10 feet 6 inches, denoting the contents of a board 14 feet long and 9 inches wide.