Circular slide rule, c 1870.
1870-1875
Bakelite "Celercertus" rotary slide rule (Brit patent no.413451)
National Coal Board methane drainage pipe calculator with pouch
Circular logarithmic slide rule by K. Emil Troger
Circular plastic slide rule
Circular slide rule for calculation in simple interest
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
A. E. W. circular slide rule
1948-1952
A.E.W. double sided circular slide rule
1948-1952
Type H circular textile calculator
1944
Circular slide rule in pocket-watch format
1880-1890
Dixon's combined circular and spiral slide rule
Circular metal slide rule by Muchall & Co.
Circular slide rule in pocket watch form
Brass circular slide rule 30cm diameter
1818-1820
Example of G. Charpentier's Calculimetre
Circular slide rule in brass
1878-1882
Lord's calculator
1837-1848
Circular slide rule
1962
Circular slide rule, 6 1/2-inch diameter, in case
Circular slide rule by Paul Pouech ("Cercle complet" model)
Circular slide rule
1955
Circular slide rule for surveying calculations: "Cox's stadia computer"
Herrmann's circular slide rule
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
Fowler Magnum long-scale calculator
circa 1940
"Automatic calculator"
Circular slide rule, 1660-1680.
1660-1680
Circular slide rule
1918-1921
"Boucher" circular calculator, by Stanley, (glass
1880-1890
Fowler long scale calculator
1920-1940
Halden "Calculex" patent circular slide rule (5 inches diameter) in case
1904-1907
Circular slide rule
Fearnley's patent Universal calculator
Circular slide rule
Circular slide rule
The "Small" Pocket Calculator
Palmer's Computing Scale
1846-1880
Circular slide rule with lockable cursor arm
Spiral scale of chords in the form of a circular slide rule
Circular slide rule (two cardboard discs with radial transparent plastic cursor) by General Industrial Co.1788 Montrose
1959-1960