Updated: Sep 28, 2018
One of the interesting tools, built upon logarithmic scales, is the slide rule. This was a handy computational device, about 12 inches long and 2 inches wide, invented in the 17th century by William Oughtred and was based on Napier's Rods. Problems requiring multiplication, division, powers, roots and the calculations of trigonometric functions were solved by adding and subtracting logarithmic scales. The instruments also served as a portable table of functions. It was the tool most commonly used by mathematicians, physicists, and engineers for more than 300 years. But when electronic calculators came into widespread use in the 1970's slide rules disappeared.