Archive of Collections



Details and Image



TypeModel No.MakerCountryConstruction
Material
DateScale LengthArea of Use
Circular and Spiral Slide Rules
Dempster / RotaRule - AA
J.R. Dempster
USA
Plastic
1933-1948
Ø 13 cm
Complex calculations

Notes: Copyrighted 2nd generation AA model (3 extra scales) with a 127 cm long-scale. Based on patented designs (US1868816 and US1849058) from 1932.


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