National Coal Board methane drainage pipe calculator with pouch
Circular logarithmic slide rule by K. Emil Troger
Circular plastic slide rule
A. E. W. circular slide rule
1948-1952
A.E.W. double sided circular slide rule
1948-1952
Circular slide rule in pocket-watch format
1880-1890
Circular slide rule, c 1870.
1870-1875
Circular slide rule for calculation in simple interest
Dixon's combined circular and spiral slide rule
Circular slide rule
Circular slide rule and time zone scale
1947
Midget circular slide rule by Dietzgen
1955
Circular slide rule in pocket watch case by Scientific Publishing Company
1900-1920
Type H circular textile calculator
1944
Circular metal slide rule by Muchall & Co.
Circular slide rule in pocket watch form
Brass circular slide rule 30cm diameter
1818-1820
Circular slide rule, 6 1/2-inch diameter, in case
Herrmann's circular slide rule
Circular slide rule in brass
1878-1882
Lord's calculator
1837-1848
Circular slide rule by Paul Pouech ("Cercle complet" model)
"Automatic calculator"
Fowler Magnum long-scale calculator
circa 1940
Example of G. Charpentier's Calculimetre
Circular slide rule, 1660-1680.
1660-1680
Circular slide rule
1962
Circular slide rule
1955
Circular slide rule for surveying calculations: "Cox's stadia computer"
Circular slide rule
1918-1921
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
Acoustic and Solar Circular Slide Rule, 1942
1942
"Boucher" circular calculator, by Stanley, (glass
1880-1890
Fearnley's patent Universal calculator
Circular slide rule
Fowler long scale calculator
1920-1940
Palmer's Computing Scale
1846-1880
Halden "Calculex" patent circular slide rule (5 inches diameter) in case
1904-1907