Inventory no. 50922 - Former Display Label
French CIRCULAR SLIDE-RULE or 'CERCLE À CALCULS'
German nickel silver, brass and celluloid; with original chamois leather case. Signed with the trade-mark, of the inventor and maker, Paul Pouech, 314 rue des Pyrénées, Paris; undated.
On the front of the instrument are two circular logarithmic scales, one on the fixed ring, the other on the moveable inner disc. These scales are for multiplication and division. Also on the moveable disc are two spiral scales for squaring and cubing numbers.
On the back are scales giving logarithms, sines and tangents. Similar scales are engraved on the inner surface of the ring and moveable disc and can be used by dismantling the instrument and reassembling it with these scales outermost.
Rules of this type were awarded a gold medal at the International Science Exhibition, Paris, 1890, and were exhibited at the Paris Universal Exhibition, 1900.
Purchased in 1952