Historical information

George Lee Lawrence (1901–1976) established a firm in Chicago to make slide rules for photography. In 1935 he moved to Wabash, Ind., renamed the company Lawrence Engineering Service, and began to manufacture general purpose slide rules. In 1938 he relocated once more to Peru, Ind., and in 1947 it was changed to Engineering Instruments, Inc., and the company remained in business until its building burned down in 1967. The model 10-B sold for 25 cents during this period. There is no record that Lawrence ever received a patent for any aspect of his design or manufacturing process.

Significance

Used up to the 1960s prior to the invention of the electronic calculator.

Physical description

10 inch one-sided wooden slide rule painted white on the front face, which consists of two divided scales, one fixed and on movable, and a sliding window called a cursor. A, D, and K scales are on the base, and B, CI, and C scales the inside of the slide. The underside of the rule is marked with: tables for equivalents and conversions. Housed in cardboard box with instruction booklet.

Inscriptions & markings

The top of the base is marked: MADE IN U.S.A. It is also marked ENGINEERING INSTRUMENTS, INC., PERU, INDIANA and PAT. PEND. Underside: This Famous Slide Rule... at a popular price. Solves Problems in Multiplication, Division, Proportion, Squares Roots, Cubes and Cube Roots, Reciprocals, etc., Instantly. Accurately Calibrated White Face on Well Seasoned Hardwood. Both ends of box: MODEL 10B-BK
Price of 15 shillings handwritten on box.