


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

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

Circular slide rule, c 1870.
1870-1875

Dixon's combined circular and spiral slide rule

Circular slide rule in pocket watch case by Scientific Publishing Company
1900-1920

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
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

Circular slide rule in brass
1878-1882

Circular slide rule, 1660-1680.
1660-1680

Lord's calculator
1837-1848

Circular slide rule
1918-1921

Textile Calculator
circa 1900

"Automatic calculator"

Acoustic and Solar Circular Slide Rule, 1942
1942

Fowler Magnum long-scale calculator
circa 1940

Example of G. Charpentier's Calculimetre
The "Small" Pocket Calculator
Fearnley's patent Universal calculator
Palmer's Computing Scale
1846-1880
Circular slide rule
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
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