Pocket Watch Style Logarithmic Circular Slide Rule Calculators

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Volume 14

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. Refer to this paper by Peter M. M Hopp Pocket Watch Slide Rules (PDF) V8.2P45 from the Journal of the Oughtred Society. and his A Fowler's Gallimaufry from the UKSRC. 18 Pocket Watch Instruction manuals for specimens in this gallery are in the ISRM Slide Rule Instructions Library, Volume 14.

Wrist Watch Time Pieces/Chronographs
with Logarithmic Scales for Calculations

Visit this forum on Breitling The Slide Rule Chronomats.

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.

Alexander Emile Boucher

Alexander Boucher (AB) Cercle A Calcul (c1885)
ISRM 22.03.25.01

Alexander Boucher (A.B.) Cercle A Calcul (c1885)
Made in Paris, France by Alexander Emile Marie Boucher
Metal face plate reads: CERCLE A CALCUL, de A.BOUCHER Bte S.D.G.D.. Script initials "AB" on reverse.
French Patent Breveté, no. 114,520 September 13, 1876. English Patent No. 4310 November 7, 1976.
52.0mm diameter x 19mm
Front scales: L, Cube Root(3 Turns)
Back scales: S, C, Square Root(2 Turns)
Original Owner: Albert Grossman/Crossman.1860-1950, who bought this in 1885.
Gift of Francis Smulder of Francis A. Smulders of West Simsbury, CT. Belonged to grandfather Albert Crossman.

Albert Grossman/Crossman (1860-1950) was born in Basil, Switzerland. He graduated with a degree in mechanical engineering in 1881 from Zurich Polytechnic, in Switzerland., which was founded by the Swiss Federal Government in 1854 with the stated mission to educate engineers and scientists. He immigrated to the United States in 1888 and became an American citizen in on December 29, 1893. Mr. Crossman worked with American sugar production in Cuba, for which he built sugar machinery and was awarded four U.S. Patents, No: 1724750; 994152; 831786; 710574. He later worked as a consultant for the H.D. Roosen Ink Company (which was incorporated in 1945, 5 years before Albert's death). He was a lifetime member of the American Society of Mechanical Engineer. The manual has a note that the A. Boucher Cercle de Calcul was purchased in 1885 in Basil, Switzerland.

Charpentier

Charpentier Calculimetre
REF

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 and 1926 Parts Diagram

Established in 1898 on Hampson Street, Manchester, England by William Henry Fowler (1853 - 1932). Fowler made over fifty variations of circular 'pocket watch' calculators with logarithmic slide rule scales. They continued manufacturing up to 1988. See Fowler history Timeline

Fowler's Junior Calculator
REF

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 Calculator
REF

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
REF

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
REF

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 Twelve-Ten Calculator
ISRM 22.04.09.01.X

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.
Gift Of Phillip Rodley of Upperhutt, New Zealand

Fowler's Universal Calculator
ISRM 18.08.06.01

John Napier and Sir Joseph Whitworth images from the manual

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
Belonged to Richard Levy (1932-2017)
Gifted by wife Midge Levy and son Benjamin Levy, Seattle, Washinbgton.

Richard Levy

Sleeve

Richard Levy 1932 - 2017 was born in London, and as a child, he was evacuated to Montreal to escape the Blitz during the WWII, He returned to London in 1943 to complete his schooling and graduated from Cambridge with a BA in Math. He married Midge in 1955, and then moved to the USA. He received a Fellowship at Princeton University and earned a PhD in Aeronautical Engineering. During this time he made extensive use of his slide rules. He returned to Montreal to begin his career at Canadair, and subsequently moved to Boston where he worked for AVCO during the 1960s and 1970s. At AVCO he began work on laser applications, and coauthored a number of patents regarding their use in the separation of isotopes which has important applications in the production of nuclear energy. This accomplishment led to the formation of a joint venture between Avco and Exxon, and in 1974 he moved to Seattle to begin work with this new entity. He left corporate life in 1980, retiring in Seattle. He spent retirement consulting and studying issues such as the Allies decision not to bomb the rail lines leading to Auschwitz. He enjoyed the outdoors, the symphony and the opera, and was proud of his heritage.

Fowler's Universal Calculator
REF

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 Vest Pocket Calculator (Long Scale)
ISRM 21.12.09.01

678KB

Leslie S. Abercrombie Jr.(1924-1921) graduated from the College of William & Mary (AB '48) and Rensselaer Polytechnic Institute (MS-MGMT '70). He served in the Naval Air Corps from 1943 to 1945 where he flew Piper Cub, SNJ and Stearman biplanes. After his discharge, Les worked as a tax accountant for the General Electric Company in Schenectady where he met his wife Madeleine (Devlin) Abercrombie of 65 years. He retired from GE in 1981. Les was privileged to participate as a WWII veteran in the Leatherstocking Honor Flight from Albany, NY to Washington, DC in 2019.

Fowler's Vest Pocket Calculator (Long Scale) c1956
Made in Manchester, England by William H. Fowler - Established 1898
70.5 mm Diameter x 11.5 mm
Front Dial: Outer "Short scale" 6.7 inches in circumference which can be used for quick Multiplication and Division. The six inner circles form a similar continuous "Long-scale" 30 inches in total circumference for more accurate multiplication and division.
Back Dial - Seven scales reckoning.inwards as follows :
No. 1. - A scale similar to the multiplying and dividing scale of the front dial.
No. 2. - A scale of Reciprocals exactly similar to Scale No. 1, but graduated contra-clockwise instead of clockwise.
No. 3. - A scale of Logarithms graduated at interval of 0.01.
No. 4. - A scale of Square roots from 0 to 100. (The values of the squares are read on Scale No. 1.) This scale extends continuously twice. round the circumference.
No. 5. - A scale of Log. Sine Values from 5° 45' to 90°.
No. 6. -.A scale of Log. Tangent Values from 5° 45' to 45°.
No. 7. - A scale of Log. Sines from 35' to 5° 45'
Note.- The values of all the functions given on Scales No. 3 to No. 7 can be read directly on Scale No. 1 by means of the Datum line, or their inverse values by reading on Scale No. 2.
Gauge Polnts: For facility in setting, both the "Short-scale" and the "Long-scale" of the front dials well as outer scales of the back dial have certain values specially indicated.
Original owner: Leslie S. Abercrombie Jr.(1924- August 1921).of Niskayuna, New York.This pocket watch slide rule was discovered in one of his suit coats.

Fowler's Long Scale Calculator
REF

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
REF

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, Guide to reading ROOTS.
Back Scales: C 6 revolution B scale, Equivalents.
Archive - Herman van Herwijnen's Slide Rule Catalogue

Fowler's Long Scale Calculator
REF

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
REF

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 Variation 1
REF

Fowler's "Magnum" Long Scale Calculator Variation 1
Note: The word "Magnum" is more pronounced and below the pivot
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 "Magnum" Long Scale Calculator variation 2 (1927)
ISRM 20.11.13.01

Fowler's "Magnum" Long Scale Calculator variation 2 - 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
Gift of Philip Rodley, Upperhutt, NZ.

Fowler's Jubilee Magnum Extra Long Scale Calculator
ISRM 15.03.06.01.X

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
REF

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

Fowler's Artillery Calculator
REF

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
REF

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 (One Knob)
REF

Fowler's Textile Calculator - Short Scale (One Knob)
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 - Short Scale (Two Knobs)
ISRM 15.09.27.08.X

Fowler Textile Calculator - Short Scale (Two Knobs)
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

Fowler's Textile Calculator - Type B (variant)
REF

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)
REF

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
REF

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

F. C. Calculigraphe

F. C. Calculigraphe (Calculating Circle) Boucher's System
REF

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

Halden, Joseph

Halden Calculex - Pocket Model ISRM 15.07.20.01 Instructions (19.2MB) and Sleeve R.W Kratz Sr. with Nick Kratz's father R.W. Kratz Jr.	Halden Calculex Patent Calculator - Pocket Model Made in Manchester, England by Joseph Halden. Manual branded for Eugene Dietzgen. 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) ] Gift of Nick Kratz of Pasadena, California. Belonged to his grandfather R.W. Kratz Sr. Nick Kratz writes" This is [part of - See K&E gallery] the combined surviving collection of my father, R.W. Kratz Jr,( - 2008) and father, R.W. Kratz, Sr.( - 1942) My grandfather (Sr.) who, amongst other things, was an electrical and HVAC engineer . My father was in International Licensing, and as i recall worked with a company in the UK (unfortunately i don't remember which company, and my father died in 2008) which licensed the Hughes-developed IC and did bring a product to market (4-function, not scientific, so not directly threatening slide rules. This would have been 1972 or thereabouts). I was 16 years old in 1975. I remember my father showing me, maybe a few years prior, how to use a slide rule. This was of course happening as the affordable scientific calculators were rolling out, bringing with them disruptive change. I never did have enough interest to learn the slide rule, with simple battery-operated greater precision at my fingertips. My loss if i survive the end of the world where there is a slide rule but no functioning calculator, though given that I'm having trouble surviving in this world as it is, I'm not particularly concerned about that. ;-) I was amongst the first engineering generation (electrical, in my case) who started out with calculators and never used slide rules."
Halden Calculex - Pocket Circular (Early) ISRM 15.09.27.06.X	Halden Calculex - Patent Circular Slide Rule (early) Note: This is an earlier version where the inner scales were blocked slightly by the knurled knobs. 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) ]
Halden Calculex - Patent Circular ISRM 21.10.25.01	Halden Calculex - Patent Circular Slide Rule (2nd Version) Made in Manchester, England by Joseph Halden Note: This is a later version where the inner scales were made with a slightly larger diameter, and the knurled knobs smaller, so the scales would not blocked by the knurled knobs. 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) ]
Halden Calculex - Desk Model REF	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

Henri Chatelain Calculigraphe

H. C. Calculigraphe (Calculating Circle) Boucher's System/a> ISRM 15.09.27.11.X	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 ISRM 15.09.27.11	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)

K&E Pocket Calculator

K&E 4018 Pocket Calculator (Circular Mannhiem)
REF

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) REF	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) REF	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

Meyrat & Perdeizet

Meyrat & Perdeizet Cercle A Calcul Slide Rule watch
REF

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

Molter, Wilhelm

Molter Slide Rule - "Mid" Model REF	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 (C), n3(K), tg, sin, log Opaque cursor grips Scan donated by Paul Tarantolo, Houston, Texas
Molter Slide Rule - Late Model REF	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
Molter (E. Gronblom) Circular Slide Rule REF	Molter (E. Gronblom) Circular Slide Rule Made in Nuremburg, Germany by Wilhelm Molter 65mm diameter x 5.5mm. Knurled disks. Front scales: A, C ( D ) Back scales: n1, n3, tg, sin, log Transparent cursor grips Labeled: E. Grönblom, Maskin A.B., Kone O.Y. Scan by Jim Bready - Conrad Schure Collection

Schacht & Westerich, Hamburg

Schacht & Westerich Pocket Circular Slide Rule
ISRM 22.03.25.02.X

Schacht & Westerich Pocket Circular Slide Rule (late Model)
Made in Nuremburg, Germany by Wilhelm Molter for Schacht & Westerich,TechnischerZeichenbedart.c1925-1939
65mm diameter x 5.5mm. Knurled disks.
Front scales: A, C ( D )
Back scales: n1(C), n3(K), tg, sin, log
Transparent cursor grips
Labeled: E. Grönblom, Maskin A.B., Kone O.Y.
Original Owner: Albert Grossman/Crossman.1860-1950, who bought this in 1885.
Gift of Francis Smulder of Francis A. Smulders of West Simsbury, CT. Belonged to grandfather Albert Crossman.

Albert Grossman/Crossman (1860-1950) was born in Basil, Switzerland. He graduated with a degree in mechanical engineering in 1881 from Zurich Polytechnic, in Switzerland., which was founded by the Swiss Federal Government in 1854 with the stated mission to educate engineers and scientists. He immigrated to the United States in 1888 and became an American citizen in on December 29, 1893. Mr. Crossman worked with American sugar production in Cuba, for which he built sugar machinery and was awarded four U.S. Patents. He later worked as a consultant for the H.D. Roosen Ink Company (which was incorporated in 1945, 5 years before Albert's death). He was a lifetime member of the American Society of Mechanical Engineer.

Gilbert Small, Waltham, Massachusetts

Photos of Gilbert and Christine Small

Gilbert Small (1885-1963) invented and manufactured The Small Calculator in 1917. Jonathan Small, his Grandson, writes: "The only tidbit I know about the Pocket Calculator is that my grandmother mentions in her diaries from the 1920s a number of occasions when she and my grandfather would spend an evening assembling calculators to fill orders. Gilbert Small was employed by an engineering firm by the name of Worcester with offices in Waltham and Boston." (Continued on right)

(Cont'd) "He was frequently required to make trips to Portland, ME, to inspect a bridge there (a bridge known as the 'Million Dollar Bridge', which has since been torn down). As a small child I knew my grandfather had invented the 'Small Pocket Calculator' because he had quite a few in stock in his home in Wayland, Massachusetts. His work was in the field of architecture for which he regularly commuted from Wayland (a suburb) to Boston by train. He was instrumental in designing the colonial style home (also in Wayland) where my parents brought up their family and lived well into their senior years, Sometimes my grandfather's work involved dismantling old historical New England homes. When this was the case he frequently salvaged and recycled useful building materials. In the case of my childhood home, this included massive exposed hand hewn beams in the living room. You could see the marks where someone had shaped the beams one axe blow after another. He also recuperated broad planks of red pine paneling and vintage bricks for that house. His architectural work prompted him to invent the 'Small Pocket Calculator'. He designed it in an era before wristwatches had come into vogue and it was common for men to carry a pocket watch. My grandfather wanted to make a calculator that would have the same small, round and convenient size and shape."

The Small Calculator (1917)
ISRM 14.06.12.01

The Small Calculator
Made in USA by Gilbert Small, Waltham, Massachusetts
United Staes Patents 657,916 Sep 18, 1900 and 1,255,939, Feb 12, 1918
Radial Scale: ( C, D )
Circular Scale Face 1: 6in Linear scale, CI, S
Circular Scale Face 2: L, A (2 concentric scales), ST
Gift Of Gretchen S. Lebrun (Canada) and Jonathan Small, Grand Children Of Gilbert Small
Related US patents: (Additional Photos courtesy of Nathan Zeldes\, Israel)

US0657916

US1255939

Scale Description

Scientific Publishing. Manchester, England.


Scientific Publishing Chronograph ISRM 15.09.27.09.X	Scientific Publishing Chronograph c1900-1910 Made in Switzerland, Distributed out of Manchester, England by William H. Fowler Fowler was also known as: Scientific Publishing Company
Scientific Publishing "The Mechanical Engineer" Chronograph ISRM 20.09.18.03.X	Scientific Publishing "The 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 80mm (3-1/4 in) diameter
Mechanical Engineer Chronograph - 3 sizes REF	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)
Scientific Publishing Single Scale REF	Scientific Publishing Single Scale c1900-1910 Distributed out of Manchester, England by William H. Fowler Fowler was also known as: Scientific Publishing Company Archive - Conrad Schure Collection

Soviet KL-1

Soviet KL-1 PocketWatch Slide Rule (Version 1) ISRM 04.09.27.03	Soviet KL-1 PocketWatch Slide Rule (Version 1) Made in USSR 5cm diameter Front Scale: A, C. Front Scale: DI, S, T. Insert (Russian) 990Kb Instruction Sheet (English) 138Kb
Soviet KL-1 PocketWatch Slide Rule (Version 2) ISRM 04.09.27.03	Soviet KL-1 PocketWatch Slide Rule (Version 2) Made in USSR 5cm diameter - Has "Price 3 Rubles 10 Kopeks" on face under circular logo. Front Scale: A, C. Front Scale: DI, S, T.
MLTZKP: Moscow Experimental [or "Pilot"] Plant for Control Devices "Kontrolpribor" Soviet KL-1 Slide Rule watch (Version 3) C10	Soviet KL-1 Slide Rule watch (Version 3) Made in USSR 5cm diameter - Alternate factory Front Scale: A, C. Front Scale: DI, S, T. Instruction Sheet (Russian) 1.9Mb Instruction Sheet (English) 138Kb
Soviet KL-1 Slide Rule watch, 50th Anniversary 1917-1967 (Version 4) REF	Soviet KL-1 Slide Rule watch, 50th Anniversary 1917-1967 (Version 4) Made in USSR 5cm diameter Front Scale Archive - Scan by Clay Castleberry, California

E.A. Sperry's Calculator

Elmer Ambrose Sperry, Sr. (1860 - 1930) was an American inventor and entrepreneur, and slide rule collectors know him for inventing the Sperry's Calculator, a pocket watch slide rule that was made and distributed by K&E starting in 1903. He was most famous as co-inventor, with Herman Anschütz-Kaempfe of the gyrocompass and as founder of the Sperry Gyroscope Company. His compasses and stabilizers were adopted by the United States Navy and used in both world wars. He also worked closely with Japanese companies and the Japanese government and was honored after his death with a biography in his honor. More than fifty years of Mr. Sperry's life had been devoted to invention. At his death, he was said to have taken out nearly 400 patents, about double the number taken out by Edison.More at Wikipedia

E.A. Sperry's Calculator ISRM 15.09.27.10.X	E.A. Sperry's Calculator - c1903 Made in USA, Mfg by K&E as No4017 - 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) Note: No fob loop on edge . Edge has #375 on it US Pat# 773,235 Oct 25, 1904, K&E Catalog Page
K&E 4017 Sperry's Pocket Calculator REF	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 REF	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 REF	K&E 4017 Pocket Calculator sn S378 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

Stanley-Boucher's Calculator (Circular Mannhiem) REF	Stanley-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 REF	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

Wichmann, Gebr., Berlin, Germany

Gebr. Wichman Pocket Watch Slide Rule (1938)
ISRM 15.09.27.07.X

Gebr. Wichmann Pocket Watch Slide Rule (1938)
Made in Berlin, Germany.
70mm diameter x 10mm
Front scales: ?, A ( B ?, ? )
Back scales: sin, F (G1, G2, G3, G4)
Note: This specimen has a cellulois lens that have faded and warped. There was excessive abrasion on one side from the lens that wiped of the scales. It's hard to see the scales so another scan was performed with the lens removed. It was then noticed that the stem which spins the center dials was missing.