A folding carpenter's measuring rule with a brass slide set into one arm - that arm and slide are a logarithmic slide rule. This is one member of the family of rules originally described by Henry Coggeshall in the 1677 pamphlet entitled Timber Measure by a Line of more Ease, Dispatch and Exactness than any other way now in use, by a Double Scale. . . ., London. This version takes the form of a 2-foot long jointed (hinged) rule with a slide set into one of the two 1-foot long legs. In addition to the slide-rule scales, there are other scales, including a ruler, on both sides of the two legs. This family of rules was particularly adapted to calculations required by timber merchants, builders, and others who dealt with length, area, and volume measurements. Coggeshall rules remained in use for approximately 200 years.
