Slide Rule Still Rules

James Alleman, a professor of civil engineering, said “For centuries anyone who built anything of any magnitude would have had to use a slide rule, The slide rule ruled.”

“There is nothing that is so troublesome to mathematical practice, nor that doth more molest and hinder calculators, than the multiplications, divisions, square and cubical extractions of great numbers, which besides the tedious expense of time are for the most part subject to many slippery errors,” Napier wrote in a book he published under the Latin title Mirifici Logarithmorum Canonis Descriptio (Description of the Marvelous Rule of Logarithms).

Six years later, English mathematician Edmund Gunter created a number line in which the positions of numbers were proportional to Napier’s logarithms, and in 1632 fellow countryman William Oughtred used Gunter’s approach and invented the first slide rule.

But, as slide rule collector Eric Marcotte points out on his dizzyingly thorough website, it took a considerable length of time to get from these early prototypes to the modern slide rule, which can be traced back most directly to Amédée Mannheim, who developed the basic 10-inch design and scale arrangement in 1850.

Alleman said he began collecting slide rules out of personal interest and for a display to coincide with civil engineering’s centennial celebration in 1987. He ruefully admits his own first slide rule isn’t in the collection.