Image: Slide rule pocket watch

Description: Russian built Circular slide rule (possibly a Tochmach KL1) with a design similar to a pocket watch showing both front and rear scales. The two pointers move in sync by rotating the red knob, and the back face (with the C scale) turns by rotating the black knob. Note the red hairline on the rear face that corresponds to the 1 on the front face. Operations that can be performed are: x,x2,x∗y,x/y,sin⁡(θ),cos⁡(θ),tan⁡(θ),tan−1⁡(x),sin−1⁡(x),cos−1⁡(x){\displaystyle {\sqrt {x}},x^{2},x*y,x/y,\sin(\theta ),\cos(\theta ),\tan(\theta ),\tan ^{-1}(x),\sin ^{-1}(x),\cos ^{-1}(x)}
Title: Slide rule pocket watch
Credit: Own work
Author: Autopilot
Usage Terms: Creative Commons Attribution-Share Alike 3.0
License: CC BY-SA 3.0
License Link: http://creativecommons.org/licenses/by-sa/3.0
Attribution Required?: Yes