LAWRENCE DeLuxe 10-B and 8-B

The Lawrence deLuxe Slide Rule was produced in the United States by Lawrence Engineering Service, later Engineering Instruments Inc., from 1935 until 1967, year the factory was destroyed by a fire. A very affordable slide rule with a beginning cost of $ 0.25 (~$4.70 now) and $0.60 (~$4.30 now) in the late 1950's, was fabricated of white lacquer coated wood, scales were initially printed on the painted surface, , and plastic cursor hold with a metallic frame. Some of the cursors had a magnifier integrated. In the 1960's this model was also fabricated with plastic laminated wood.

The 10-B model, the most well-known product of this company, was commercialized as an indispensable aid in solving problems in MULTIPLICATION, DIVISION, CIRCUMFERENCES, and AREAS OF CIRCLES, SQUARES, SQUARE ROOTS, CUBES, CUBE ROOTS, PROPORTION, etc, the scales on this rule are: A [ B, CI, C ] D, K on the front face, no scales on the slider's back. and a table with slide rule use instructions the back face, was the rule for the basic levels' student and for common people that in modern times were using a four-functions calculator to perform simple operations, other than addition-subtraction.

This model was produced in two sizes: 10-B (10" long - 9.5" long scales) and 8-B (8" long - 7.5' long scales), and had no serial numbers or other code helping to determine the production year, so I only can affirm that the specimens in this collection are 53+ years old. The 8-B specimen is branded DU MONT Zanesville, Ohio. I have not found any information about this company, only other like this in other collection; the only reasonable conclusion is that Lawrence Engineering Services manufactured for other companies.

It is important to remark that Lawrence Engineering Services - Engineering Instruments fabricated other very interesting specific purpose rules, some of them, the Poker Meter, the Key and Chord Transposer, and the Voltage Drop Calculator, in this collection.