Therefore the mold is made an amount larger to offset the shrinkage. Patternmakers used these specially made rules for each type of metal they poured. The adjacent table gives the correct length for each size diameter stopper for the commonly used lengths of Shorts, Regulars and Extra Longs. The number of board feet of lumber attained from a sawn log depends on the diameter and length of the log. A log rule , used to measure board feet as a function of diameter was used.
Most states have laws defining which scales are to be used for inventorying or quoting saw logs.
I am aware of at least 28 different scales. Some are listed in the adjacent table. From 1817 until about 1880 these squares were made of iron. Since 1880 all squares have been made of steel, although the original name of iron has clung to them.