Instruction Manual for Pickett Slide Rules with Ln-L Scales

Maurice Hartung of the University of Chicago wrote this sixteen-page booklet to explain the use of natural log and logarithmic scales placed on Pickett's line of "dual-base" slide rules. Its citation information is: Maurice L. Hartung, How to Use Ln-L Scale Slide Rules (Santa Barbara, Calif.: Pickett, Inc., n.d.). The logo and address on the cover were in use from 1964.

Pickett used these scales on several models represented in the Smithsonian collections, including 3, 4, 515, 600, and 1010. The rules depicted in the booklet are models 1011 and 4, similar to 2000.0203.01. Hartung explains how to find logarithms and natural logs (by reading the mantissa), powers of e and 10, logarithms of proper fractions, powers for negative exponents, and the characteristic. He explains how to place the decimal point and how to correct for the error introduced when the number 2.3 is used to estimate e. He then covers multiplication, division, logarithms of combined operations, powers of other bases, hyperbolic functions, and applied problems.

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