"Boucher" circular calculator, by Stanley, Great Turnstile, London "Boucher" circular calculator, by Stanley, (glass Mathematics 1880-1890
Circular slide rule with lockable cursor arm, plastic made by Lithocalculator Company, Calfornia, USA. Circular slide rule with lockable cursor arm Mathematics
Halden "Calculex" patent circular slide rule (5 inches diameter) in case, c. 1906 Halden "Calculex" patent circular slide rule (5 in Mathematics 1904-1907
Palmer's Computing Scale, improved by Fuller, (a circular logarithmic slide rule, with numerous gauge points); on reverse side "Fuller's Time Telegraph" Palmer's Computing Scale, improved by Fuller Mathematics 1846-1880
Circular slide rule, Fowler "Magnum", in leather case with descriptive leaflet Circular slide rule, Fowler "Magnum", in leather c Mathematics
Fowler long scale calculator, circular slide rule with carrying case and instruction booklet, 1920-40. Fowler long scale calculator, circular slide rule Mathematics 1920-1940
German circular slide-rule, type KRS 40, No.1246, 17 1/2 inches diameter, fitted in a metal case 18 1/2 x 20 inches German circular slide-rule, type KRS 40, No.1246, Mathematics
Circular slide rule, Fowler "Magnum" long-scale calculator, in fitted case with instruction booklet by Harold Fowler Circular slide rule, Fowler "Magnum" long-scale ca Mathematics
Spiral scale of chords in the form of a circular slide rule, with celluloid cursor in metal mount, cardboard 4 13/16-inch diameter with descriptive leaflet Spiral scale of chords in the form of a circular s Mathematics
Circular slide rule by Pickett, metal and plastic, in leather pouch with instruction booklet Circular slide rule by Pickett, metal and plastic, Mathematics
Circular slide rule by Fowler and Co., Manchester, model RX, double faced, serial no. 7384, with descriptive leaflet in metal case Circular slide rule by Fowler and Co., Manchester, Mathematics
Fearnley's patent Universal calculator, circular slide rule with cardboard scale in fitted mahogany case, unsigned, British,1880-1900. Used at the University Observatory, Cambridge, at Madingley Road, Cambridge, England. Fearnley's patent Universal calculator, circular s Mathematics
Circular slide rule (two cardboard discs with radial transparent plastic cursor) by General Industrial Co.1788 Montrose, Chicago 13,Illinois, also marked Slide Chart Corp., 1959, Perrygraf, Marywood, Illinois Circular slide rule (two cardboard discs with radi Mathematics 1959-1960
The "Small" Pocket Calculator, a circular slide rule patented 1918, made by G. Small, Boston, in leather pouch The "Small" Pocket Calculator, a circular slide ru Mathematics
Circular slide rule, Halden 'Calculex', in leather pouch with instruction booklet Circular slide rule Mathematics
Circular slide rule with lockable cursor arm, plastic, in envelope with instructions: " Eckel dial rule", Engineers' Model, made by Lithocalculator Company, Calfornia Circular slide rule with lockable cursor arm, plas Mathematics
