Back in the days before electronic slide rules
did not exist, engineers and physical scientist relied on a primative device called the slide rule. . This device did not have any buttons and no batteries to run down.
A good slide rule could replace many mechanical devices including the adding machine and the Spirule for root locus diagramming.
Slide rule accuracy was an issue during WW II where artillery forces and navigation were crucial. The Norton bomb-sight was actually a combination of three slide rules with two directional velocity sensors and a gradient calculator. I am aware of slide rules lengths of 72 inches used for airfoil design.
The slide rule is based on Euler’s work with logarithms.
Today, the common slide rule is but a fading memory, but it was used by people vibrantly alive today in their daily work.
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