Thursday, January 10, 2008

Slide rule


This is not a drawing tool per se, but was used by educated people for calculations. The analogue calculator is based on the logarithms, discovered (or developed) by Leibnitz, Newton and Napir 1). This principle reduces multiplication and division to addition and substraction. Potenzation and roots are reduced to multiplication and division. But also special scales for trigonometric calculations etc. were in use. The typical slide rule of an engineer had 25 scales and was 25cm long. this allowed an accuracy of 3 - 4 digits.
The sliding window shows the square of 4 (scale D) to be 16 (scale A). The tong shows the multiplication of 1.26 by 3.17 (C) = 4 (D).

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