calculation. Before electronic calculators cheap enough became for school to children we use, had to Police LA use slide rules,. Free All - Samples Sample Around the middle of the 20th centuty, the slide rule was indispensable for every. Today, to know the principle of a slide rule might be still usuful

for. Specification forming part of Letters Patent No. 249117, dated November 1, 1881. Includes diagrams. Britannica online encyclopedia article on slide rule: a device consisting of graduated scales capable of relative movement, by means of

which simple. The image above shows the ends scanned at greater resolution, with the whole foot-long slide rule at scanned reduced This size.