Circular logarithmic slide rule by K. Emil Troger
Circular plastic slide rule
Circular slide rule for calculation in simple interest
A. E. W. circular slide rule
1948-1952
A.E.W. double sided circular slide rule
1948-1952
Circular slide rule in pocket watch case by Scientific Publishing Company
1900-1920
Dixon's combined circular and spiral slide rule
Circular slide rule, c 1870.
1870-1875
National Coal Board methane drainage pipe calculator with pouch
Type H circular textile calculator
1944
Circular slide rule in pocket-watch format
1880-1890
Circular slide rule
Circular slide rule and time zone scale
1947
Midget circular slide rule by Dietzgen
1955
Circular metal slide rule by Muchall & Co.
Circular slide rule in pocket watch form
Brass circular slide rule 30cm diameter
1818-1820
"Automatic calculator"
Circular slide rule, 6 1/2-inch diameter, in case
Circular slide rule by Paul Pouech ("Cercle complet" model)
Herrmann's circular slide rule
Example of G. Charpentier's Calculimetre
Circular slide rule in brass
1878-1882
Circular slide rule, 1660-1680.
1660-1680
Lord's calculator
1837-1848
Circular slide rule
1918-1921
Acoustic and Solar Circular Slide Rule, 1942
1942
Circular slide rule
1962
Circular slide rule
1955
Circular slide rule for surveying calculations: "Cox's stadia computer"
Circular slide rule: "Dialor for calculation of vibration level for random noise of uniform spectral density"
Circular No.101C dial slide rule with sythetic leather case and instructions
1965-70
Rectangular plastic slide-chart made by Perrygraf for complimentary distribution by IBM Federal Systems Division
Textile Calculator
circa 1900
Fowler Magnum long-scale calculator
circa 1940
"Boucher" circular calculator, by Stanley, (glass
1880-1890
Fearnley's patent Universal calculator
Fowler long scale calculator
1920-1940
Halden "Calculex" patent circular slide rule (5 inches diameter) in case
1904-1907
Circular slide rule
Circular slide rule
Palmer's Computing Scale
1846-1880