Pocket Watch Style Logarithmic Calculators

KEEP ISRM FREE!
This page contains circular slide rules in the form of a pocket watch. They are not time pieces. Many are very rare as the metal deterioriated faster than other materials over time. The more modern Russian KL-1 is still widely available. Thanks to the members of the UK Slide Rule Circle and of the Oughtred Society for most of the scans provided in this gallery.

Wrist Watch Time Pieces/Chronographs
with Logarithmic Scales for Calculations


Visit this forum on Breitling The Slide Rule Chronomats
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Swiss makers, and brands made by the Swiss, were Arios, Breitling, Camy, Certina, Chase Durer, Cimier, Clebar, CX Swiss Military, ESQ, Fortis, Fero, Formex, Gallet, Girard-Perregaux, Hacher, Hamilton, Heuer, Ikepod, Juvenia, LeCoultre, Luminox, MIMO, Mondia, Ollech & Wajs, Orator, Revue Thommen, Sector, Selectron, Sheffield, Sinn, Sicura, Sorna, Tissot, Torgoen, Tourneau, Ventura, Wenger, Wittnauer, Zeno. French makers were: Meyrat & Perdrizet, Eberjax and Yema. Post WWII japanese manufacturers were: Seiko, Citizen, Casio, Orient and Kentex. Other known manufacturers are/were: Abingdon, Accurist, Aeromatic, Alpha, Anonimo, Bulova, Ellesse, Estana, Honda, Invicta, Jeep, Jules Jurgensen, Kenneth Cole, Kienzle, National Geographic, Nautica, Sea Gull, Sekonda, Timex, Tommy Bahama, Trias, Poljot, Rendex, Rotary, and Vostok. Many are now replicas out of China.

The modern slide rule/chronograph wristwatch has a relatively recent origin, arriving in 1940 during the beginnings of World War 2 by the Swiss, although the first known example of a time piece with a calculator was by the French Meyrat & Perdrizet around 1890. This was in the form of a pocket watch as seen here.


French Meyrat & Perdrizet (1890)

The beginning of WWII brought an influx of orders to the Swiss watch manufacturers from all over the world, and with it came the introduction of new watch models with new features. A slide rule wristwatch has two (or more) logarithmic scales. Usually, one scale is on a movable bezel, and a second is fixed or printed on the face of the watch. Calcuations are made by rotating the bezel to fix the relative position the two scales. The two scales form proportions that are useful in math problems involving multiplcation and division. The first three modern manufacturers, all Swiss, were Breitling, Juvenia and MIMO.

Charpentier



Charpentier Calculimetre
Charpentier Calculimetre
Made in France - 5.92cm diameter
Front Scale: D, C ( W1, W2)
Back scale: L, S, T
Archive - Giovanni Breda Collection

Fowler & Co. Manchester, England.


1905 Photo
Established in 1898 on Hampson Street, Manchester, England by William Henry Fowler (1853 - 1932). Fowler made over fifty variations of circular 'pocket watch' calculatorswith logarithmic slide rule scales. They continued manufacturing up to 1988. See Fowler history Timeline
See Fowler's Long Scale Calculator Instructions by Ron Manley, UK.


Mechanical Engineer Chronograph - 3 sizes
Mechanical Engineer Chronograph c1900-1910
Made in Manchester, England by William H. Fowler
Fowler was also known as: Scientific Publishing Company
Archive - Jim Bready Collection (UK)


Mechanical Engineer Chronograph
Mechanical Engineer Chronograph c1900-1910
Made in Switzerland, Distributed out of Manchester, England by William H. Fowler
Fowler was also known as: Scientific Publishing Company
Archive - Scan by Clay Castleberry Collection (California)



Fowler's Junior Calculator
Fowler's Junior Calculator
Made in Manchester, England by William H. Fowler 
9 cm diameter
Front Scales: C, CI, L, cube root (3 circle), S (2 circle), T
Back Scales: C (D, L, square roots (2 circles), S, T)
Archive - Courtesy of Rod Lovette's Collection (UK)


Fowler's Twelve-Ten Calculator
Fowler's Twelve-Ten Calculator
Made in Manchester, England by William H. Fowler 
8.6 cm diameter
Front Scales: C, CI, D, D, S, ST, T
Note: Two "D" scales. On sub-divided in tenths and the other twelfths.
Archive - Courtesy of Rod Lovette's Collection (UK)


Fowler's Calculator
Fowler's Calculator
Made in Manchester, England by William H. Fowler 
68 mm diameter
Front Scales: D, C, B, A
Back Scales: L, C, A, S
Archive - Herman van Herwijnen's Slide Rule Catalogue


Fowler's Calculator - Type H
Fowler's Calculator - Type H
Made in Manchester, England by William H. Fowler 
68 mm diameter x 13mm
Front Scales: C(short scale), CI, L, A(2 turns), S
Back Scales: C(short scale Cubes), K (3 turns Cube roots)
Scan donated by Paul Tarantolo, Houston, Texas


Fowler's Calculator - Type RX
Fowler's Calculator - Type RX
Made in Manchester, England by William H. Fowler 
68 mm diameter x 13mm
Front Scales: C(short scale), C(long scale - 6 turns)
Back Scales: C(short scale), CI, L, A (2 turns), S
Scan donated by Paul Tarantolo, Houston, Texas


Fowler's Universal Calculator

ISRM 12.09.04.0
Fowler's Universal Calculator
Made in Manchester, England by William H. Fowler 
86mm diameter x10 mm
Front Scales: Conversion Yards to Metres, C CI Logs 100-10 (in 3 circles), sin(6°-70°), sin(0°-5°), tan
Acquisition made possible by donations from the Huang Collection and Scott Reynolds


Fowler's Universal Calculator
Fowler's Universal Calculator
Made in Manchester, England by William H. Fowler 
86mm diameter x10 mm
Front Scales: Conversion Yards to Metres C CI L 100-10 (in 3 circles), sin(6°-70°), sin(0°-5°) tan
Archive - Herman van Herwijnen's Slide Rule Catalogue


Fowler's Long Scale Calculator
Fowler's Long Scale Calculator - Established 1898
Made in Manchester, England by William H. Fowler
68.5 mm Diameter x 11.5 mm
Front Scales: L 3 revolution B scale
Back Scales: C 6 revolution B scale
Courtesy of Rod Lovette's Collection (UK)


Fowler's Long Scale Calculator
Fowler's Long Scale Calculator - Established 1898
Made in Manchester, England by William H. Fowler
68.5 mm Diameter x 11.5 mm
Front Scales: L 3 revolution B scale
Back Scales: C 6 revolution B scale
Archive - Herman van Herwijnen's Slide Rule Catalogue


Fowler's Long Scale Calculator
Fowler's Long Scale Calculator
Made in Manchester, England by William H. Fowler 
68.5 mm diameter x 11mm
Front Scales: C(short scale), C(longscale - 6 turns)
Back Scales: None
Scan donated by Paul Tarantolo, Houston, Texas


Fowler's Long Scale Calculator - 3 stems
Fowler's Long Scale Calculator - 3 stems
Made in Manchester, England by William H. Fowler 
68 mm diameter x 11mm
Front Scales: C(short scale), C(longscale - 6 turns)
Back Scales: C(short scale), CI, L, A(2 turns), LogS, LogT, LogS
Scan donated by Paul Tarantolo, Houston, Texas


Fowler's "Magnum" Long Scale Calculator
Fowler's "Magnum" Long Scale Calculator - 1927
Made in Manchester, England by William H. Fowler
11.9 cm (4-5/8") Diameter x 1.1 cm
Front Scales: C (short scale), CI, R1, R2, L, C (6 turn long scale 50"), S, S, T
Back Scales: None
Courtesy of Rod Lovette's Collection (UK)


Fowler's "Magnum" Long Scale Calculator Variation 1
Fowler's "Magnum" Long Scale Calculator Variation 1
Made in Manchester, England by William H. Fowler
11.9 cm (4-5/8") Diameter x 1.1 cm
Front Scales: C (short scale), CI, R1, R2, C (6 turn long scale 50"), L, S, S, T
Back Scales: None
Courtesy of Rod Lovette's Collection (UK)


Fowler's Jubilee Magnum Extra Long Scale Calculator

ISRM 15.03.06.01
Fowler's Jubilee Magnum Extra Long Scale Calculator
Made in Manchester, England by William H. Fowler 
119.5mm diameter x 11 mm
Front Scales: Metric Conversions, C, CI, L, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11
Note: Acquired from the United KIngdom


Fowler Artillery Calculator
Fowler Artillery Calculator
Made in Manchester, England by William H. Fowler 
Scan donated by Christopher Johnston, Omaruru Namibia


Fowler's Artillery Calculator
Fowler's Artillery Calculator
Made in Manchester, England by William H. Fowler 
68 mm diameter x 11mm
Front Scales: C(short scale), CI, LogSine, LogTan, Log Sine (small angle), Log
Back Scales: Conversions: Yards/Miles, Miles/Km, Inches/mm, mm/inches
Scan donated by Paul Tarantolo, Houston, Texas


Fowler's Textile Calculator - Type E1
Fowler's Textile Calculator - Type E1
Made in Manchester, England by William H. Fowler 
68 mm diameter x 10.5mm
Front Scales: C(short scale), 8's
Back Scales: Circular Table: Wefts, Looms, Reeds
Scan donated by Paul Tarantolo, Houston, Texas


Fowler's Textile Calculator - Short Scale Type
Fowler's Textile Calculator - Short Scale Type
Made in Manchester, England by William H. Fowler 
68 mm diameter x 10.5mm
Front Scales: C(short scale), 8's
Back Scales: Circular Table: Wefts, Looms, Reeds
Scan donated by Paul Tarantolo, Houston, Texas


Fowler Textile Calculator
Fowler Textile Calculator - 2.5 inch diameter
Made in Manchester, England by Fowler's Calculators Ltd
Courtesy of Rod Lovette's Collection (UK)


Fowler's Textile Calculator - Type B (variant)
Fowler's Textile Calculator - Type B (variant)
Made in Manchester, England by William H. Fowler 
87 mm diameter x 11mm
Front Scales: C(short scale - 10ths and 16ths)
Back Scales: None
Scan donated by Paul Tarantolo, Houston, Texas


Fowler's Textile Calculator - Type B (variant)
Fowler's Textile Calculator - Type B (variant)
Made in Manchester, England by William H. Fowler 
87 mm diameter x 11mm
Front Scales: C(short scale - 10ths and 16ths) ? Scale (-40 to +60)
Back Scales: None
Scan donated by Paul Tarantolo, Houston, Texas


Fowler "Magnum" Textile Calculator
Fowler "Magnum" Textile Calculator
Made in Manchester, England by Fowler's Calculators Ltd
Scan donated by Monroe Postman, Los Altos, California

Halden, Joseph



Halden Calculex - Pocket Model
Halden Calculex - Pocket Model
Made in Manchester, England by Joseph Halden
61mm diameter x 7.5mm
Front scales: L, A [ B C(Square Root of B) ]
Back scales: Degrees, A [ B(inverted), C(Cube Root of B) ]
Scan donated by Paul Tarantolo, Houston, Texas


Halden Calculex - Desk Model
Halden Calculex - Desk Model
Made in Manchester, England by Joseph Halden
126mm diameter x 15mm
Front scales: L, A, [ B, C(Square Root of B) ]
Back scales: Degrees, A [ B(inverted), C(Cube Root of B) ]
Scan donated by Paul Tarantolo, Houston, Texas

F. C. Calculigraphe



F. C. Calculigraphe (Calculating Circle) Boucher's System
F.C. Calculigraphe (Calculating Circle) Boucher's System
Made in Paris, France (possibly by Henri Chatelain's brother Fred, c.1878)
52.5mm diameter x 17.5mm
Front scales: L, Cube Root(3 Turns)
Back scales: S, C, Square Root(2 Turns)
Scan donated by Clay Castleberry, California

Henri Chatelain Calculigraphe



H. C. Calculigraphe (Calculating Circle) Boucher's System
H.C. Calculigraphe (Calculating Circle) Boucher's System
Made in Paris, France by Henri Chatelain, c.1878
52.5mm diameter x 17.5mm
Front scales: L, Cube Root(3 Turns)
Back scales: S, C, Square Root(2 Turns)
Scan donated by Paul Tarantolo, Houston, Texas
Instructions 2.8Mb


H. C. Calculigraphe (Calculating Circle) Boucher's System
H.C. Calculigraphe (Calculating Circle) Boucher's System
Made in Paris, France by Henri Chatelain, c.1878
Note logo graphic below H.C.
52.5mm diameter x 17.5mm
Front scales: L, Cube Root(3 Turns)
Back scales: S, C, Square Root(2 Turns)
Scan donated by Clay Castleberry, California

K&E Pocket Calculator



K&E 4018 Pocket Calculator (Circular Mannhiem)
K&E 4018 Pocket Calculator sn 548 - c1913
Made in USA, Mfg by K&E, Designed by George Lange, US Pat# 1,012,660, Dec 1911
Front Scale: (C, D)
Back scale: Tangents, Log, (Sines)
Note: Scales are: Stationary (Revolving)
Archive - Photo by Elliot Pearce Family - Original owner, James A. Pearce was a railroad civil engineer and WWI veteran.

Lord's Calculator



Lord's Calculator - (R. Waddington)
Lord's Calculator - (R. Waddington)
Made in Coventry, England by R. Waddington
70mm diameter x 17mm
Scales: D ( C ) ( B ) A(inverted) / W
Note: Unusual inner scale with W scale (-30 to +60) inserted into inverted logarithmic A scale.
Scan donated by Paul Tarantolo, Houston, Texas


Lord's Calculator - (Elliot Brothers)
Lord's Calculator - (Elliot Brothers)
Made in LOndon, England by Elliot Brothers
65mm diameter x 12.5mm
Scales: D ( C ) ( B ) A(inverted)
Scan donated by Paul Tarantolo, Houston, Texas

Molter, Wilhelm



Molter Slide Rule - "Mid" Model
Molter Slide Rule - "Mid" Model
Made in Nuremburg, Germany by Wilhelm Molter
65mm diameter x 5.5mm
Front scales: A, C ( D )
Back scales: n1, n3, tg, sin, log
Opaque cursor grips
Scan donated by Paul Tarantolo, Houston, Texas


Molter Slide Rule - Late Model
Molter Slide Rule - Late Model
Made in Nuremburg, Germany by Wilhelm Molter
65mm diameter x 5.5mm
Front scales: A, C ( D )
Back scales: n1, n3, tg, sin, log
Transparent cursor grips
Scan donated by Paul Tarantolo, Houston, Texas

G. Small (Boston)



G. Small - Pocket Calculator
G. Small - Pocket Calculator, c.1918
Made in U.S.A. by G. Small of Boston
Patent February 12, 1918
49mm diameter x 11mm
Front scales: 6", C, S
Edge scales: C || D
Back scales: L, A(2 turns), ST
Note: The edge scales slide past one another when the two halves are rotated.
Scan donated by Paul Tarantolo, Houston, Texas

Soviet KL-1




C10 Soviet KL-1 Slide Rule watch
Soviet KL-1 Slide Rule watch
Made in USSR 5cm diameter
Front Scale
Instruction Sheet (Russian) 1.9Mb
Instruction Sheet (English) 138Kb



REF - Soviet KL-1 Slide Rule watch
Soviet KL-1 Slide Rule watch
Made in USSR 5cm diameter
Front Scale
Archive - Not in collection
Insert (Russian) 990Kb
Instruction Sheet (English) 138Kb


REF - Soviet KL-1 Slide Rule watch, 50th Anniversary 1917-1967
Soviet KL-1 Slide Rule watch, 50th Anniversary 1917-1967
Made in USSR 5cm diameter
Front Scale
Archive - Scan by Clay Castleberry, California

Meyrat & Perdeizet



REF Meyrat & Perdeizet Cercle A Calcul Slide Rule watch
Meyrat & Perdeizet Cercle A Calcul Slide Rule watch
Made in France - 6 cm diameter, Circa 1880, French patent #139898
Front Scale: C ( D )
Archive - Scan by Clay Castleberry, California
Inner Works


Sperry's Pocket Calculator



K&E 4017 Sperry's Pocket Calculator
K&E 4017 Sperry's Pocket Calculator - c1908-1911
Made in USA, Mfg by K&E - Designed by Elmer A. Sperry, US Pat# 773,235 Oct 25, 1904
Dual Revolving Scales:
S Dial: Tan, Log (equal parts), Sin (2 spirals)
L Dial: C (3 spirals)
Archive - Ebay picture, Courtesy of Clark McCoy


K&E 4017 Sperry's Pocket Calculator
K&E 4017 Sperry's Pocket Calculator - c1903
Made in USA, Mfg by K&E - Designed by Elmer A. Sperry, US Pat.#773,235
Dual Revolving Scales:
S Dial: Tan, Log (equal parts), Sin (2 spirals)
L Dial: C (3 spirals)
Archive - Ebay picture, Courtesy of Clark McCoy


K&E 4017 Sperry's Pocket Calculator
K&E 4017 Pocket Calculator sn S978
Made in USA, Mfg by K&E, - Designed by Elmer A. Sperry, US Pat.#773,235
Dual Revolving Scales:
S Dial: Tan, Log (equal parts), Sin (2 spirals)
L Dial: C (3 spirals)
Archive - Ebay picture, Courtesy of Clark McCoy

Stanley-Boucher



Boucher's Calculator (Circular Mannhiem)
Boucher's Calculator
Made in London, England by W.F. Stanley
52mm diameter x 14.5mm
Front scales: S , C Square Root(2 Turns)
Back scales: L, Cube Root(3 Turns)
Scan donated by Paul Tarantolo, Houston, Texas


Stanley-Boucher's Calculator
Stanley-Boucher's Calculator
Made in London, England by W.F. Stanley
52mm diameter x 16mm
Front scales: S, C, Square Root(2 Turns)
Back scales: L, Cube Root(3 Turns) Decimal Point Counter
Scan donated by Paul Tarantolo, Houston, Texas

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