Description

Complex Scales by Engineer to Brunel, English, late 19th century, signed “Metfords Engineers Pocket Scales” and “Hudson & Kearns, London.” The four ivory rules are each 6-1/2″ (17 cm) long, of triangular cross section, and divided on all three sides with scales, constants, measured values, equations, etc. There are simple linear charting scales very finely divided (e.g., “6 inches to a mile”); relationships in triangles (“Hypoth= Base x Sec Angle at Base”); “Ordnance Scale;” expansion measurements for mercury, for glass tubes, for steel rods, etc; specific gravity of palladium, aluminum, etc; the logarithm of the force of gravity; the one-hundredth of a second of arc at the equator, measured in English feet; etc. We count 17 divided scales and numerous useful facts. Cryptic abbreviations on the ends of each rule form a table of contents. Condition is excellent except for a small chip at one end of one rule. The original leather bound case is present, lacking its end piece.

The inventor was presumably William Ellis Metford (1824 – 1899), a dedicated engineer who worked under Brunel for a time, and who is known for his improved surveying theodolite (see his high quality miniature theodolite “The Metford Theodolite with Repeating Circle,” Tesseract Catalogue 64 Item 23.) One example of “Metford’s Double Set of Ivory Pocket Scales suitable for Civil Engineers, Architects, and Land Surveyors” is presumably in the Science Museum — we find it listed in the Catalogue of the Educational Division of the South Kensington Museum (1867). That set was signed by Pastorelli & Co.; ours by Hudson & Kearns, known especially as publishers in late Victorian England. A rare example of this complex set.