1950s 18" Beveled Aluminum Rule with 1/32 Graduations and 36 cm Graduations

This is an 18" beveled aluminum rule with 1/32" graduations on one side, and 36 cm graduations on the other. The center of the rule consists of conversions from fractions to decimals, the name of the decal (Metal Cal), and the name of the decal's manufacturer (C & H Supply Co., 415 E. Beach Ave.). The “pat. pending” would indicate the rule dates before 1956 when Metal Cal’s patent (No. 2,769,265) was issued to the Boeing Co. and licensed to C & H Supply Co. The rule otherwise does not indicate its manufacturer (unless it is under the Metal Cal decal).

The rule is also affixed with oblong aluminum mounts at both ends that allow the rule to be attached to a drafting machine. One mount is marked: VARD INC. PATENT NO. 2192422. On-line I found that Vard Beecher Wallace (1901–1988) of Sierra Madre, Calif., applied for a patent for these attachments in 1939 and received it the next year. Vard Mechanical Laboratory supplied drafting machines to aircraft engineers such as Allen Lockheed and Jack Northrop. VML was renamed Vard, Inc., by 1945 and was purchased by Royal Industries in 1959.