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Circular Slide Rules and selected Disk Charts |
KEEP ISRM FREE! Donations are tax deductable |
This gallery has a wide variety of circular slide rules and many of these images may be duplicated on their
respective manufacturer or country galleries. The well-known Gilson Binaries/Atlas, the Concise line of products, and Aristo, Faber-Castell, and Pickettcircular slide rules have been moved to those respective galleries, along with Controller, Norma and Standardgraph into the Germany/DDR gallery. Specialized/promotional cardboard/plastic film
circular slide rule/calculators are also found at the Slide Charts Gallery. The advantage of circular slide rules, is that the dimensions can be small enough to fit in your shirt pocket, yet have the scale resolution of a standard linear slide rule. Construction is simple as the only only fastener is the single screw or rivet at the center of the disk. A few Disk Charts are ahown which logarithmic scales or of unusual construction. From a 1988 speech by Seymour Cray (1925-1996), father of the super-computer, In college I had a circular slide rule, the 10-inch model. That's as big as circular slide rules were made, so I had the very top of the line. If you had a circular slide rule, you had some social problems in college. Almost everyone else had a straight-stick slide rule, and they came in a nice leather case with loops on the back so you could hang them on your belt. Those of us with circular slide rules couldn't do that, so people looked at you kind of funny and thought, `Do you suppose he's really not an engineer?'. |
Manufacturers found in this gallery (in no particular order), Alro, Dempster, Boykin, Huet, Amphenol, Miller Dial,
C-Thru, General Electric, Martin Company, Layne (Thomas Sheahan designs), G. Felsenthal & sons, General Luminescant Corp, Cruver Manufacturing Co., J.B. Carroll Company, Weems System, Weems & Plath, American Airlines, Jeppsen, Whitehead, Aero Products Research, Science Spectrum Inc.,
White & Gillespie, American Hydromath Company, T&T Calculator, Associated Spring Corp, Standardgraph, Gilson, Compass, Dietzgen, Pickett, Aristo, faber-Castell, Lietz, SIC, Scientific Instruments, Concise, Sama&Etani, Lafayette, US Army Signal Corps, Cox, Hemmi, Norton & Gregory, Controller Calculator, Mascot, Circhlow, Emeloid Operations, Graphic Calculator Co., Ahrend, Waltham, Educational Instruments, Inc., Chadwick, Gong Se He Ying. |
OAO Kalibr Moscow Circular Slide Rule Calculator REF |
OAO Kalibr Moscow Circular Slide Rule Calculator Made in USSR by OAO Kalibr-Moscow Front Scale (with logo) K, A, C ( D, CI ) Back Scale: T, ST, S ( C, L ) Photo Contributed By Dushan Grujich Collection, Australia |
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Allegheny Plastics Circular 1948 4.38 dia ISRM 13.00.00.99 |
Allegheny Plastics Circular 1948 4.38 dia Made in USA by Allegheny Plastics, Inc Thorn Run Road, Coraopolis, PA. Front Scale: K1, D1, A1, L0 ( C1, B1, CI1) Back Scale: 360° protractor, Fraction to Decimal and Temperature conversions. Instructions (PDF) |
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ALRO PATENT System ALRO 200R ISRM 13.01.26.01 |
ALRO PATENT System ALRO 200R Made in The Hague, Holland Dimensions: 125x135x12 mm Patents No's (stamped on metal hub): USA 2,117,155; France 808,295; Gr. Britain 443689; Belgium 413,897; Germany 643,571; Holland 41,324 Front Scale S, T, S&T, kW, N2, N ( N , N2, R, N3) Cover Scale: Decimal/fraction, Log spiral scale Acquired from the Netherlands, made possible by a gift from Robert L. Allison of Ballard, Washington. See many more specimens in the ALRO gallery here at ISRM. |
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Dempster RotaRule - model AA (Dietzgen 1798 w/Case) ISRM 13.05.28.01.X Instruction Sheet, Legal size, two front and back sheets |
Dempster RotaRule - Model AA (1933-1948) Made in USA - Designed and manufactured by Jack Dempster, Berkeley, California. Front Scales: K, A, D ( C, CI, CIF, S, CS, ST, T, CT, G, B, F/i ) Back Scales: 1-100 in 4circles, DLL, V2 ( V1, 1-100 in 4circles, LL3, LL2, LL1, LL%, L ) Acquisition made possible by contributions from Dick Rose Vintage Instruments Dietzgen Model 1798C leather case, Model 1798 shown in 1938 Dietzgen Catalog (in ISRM Library), additional image from Hermann's Slide Rule Catalog as ISRM specimen has a faded back cursor.
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REF - Boykin RotaRule - model 510 REF |
Boykin RotaRule - Model 510 (1960-1973) Made in USA - Designed by Bernard C. Boykin (1921-2011), Ruxton, Maryland. Front Scales: K, A, D ( C, CI, CIF, S, CS, ST, T, CT, B, L ) Back Scales: D50:1-100 in 4 circles, DLL (V2, V1 C50:1-100 in 4 circles, LL3, LL2, LL1, LL01, LL02, L03 ) Archive - Various sources Bernard C. Boykin passed away May 12, 2011. He was born in Ruxton, Maryland in 1921. He earned a BS degree in Chemistry from Williams College in 1942/43 and another BS degree in Chemical Engineering from John Hopkins University in 1954. During World War II he was a radar officer in the United States Navy. After the war he designed the Boykin RotaRule, a very complex disk slide rule used by engineers and scientists for their calculations. It was based on the Dempster's Rotarule design who's patent had expired, but with improved scales. The trig scales are in decimal degrees. | ||||
Huet MG 240C Circular REF |
Huet MG 240C Circular Made in France - 1925br> Front Scale (Long Spiral): Sines, Tangents, Metres Archive - Courtesy of Rod Lovette's Collection (UK) |
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Amphenol Circular Slide Rule & RF Smith Chart ISRM 13.02.13.05 Note: Bunker Ramo Corporation was founded by George M. Bunker and Simon Ramo in 1964, jointly owned by Martin-Marietta and Thompson Ramo Wooldridge TRW. The resulting company, Bunker-Ramo, was based in Trumbull, Connecticut.It became a manufacturer of military electronics devices and digital computers. In 1967 the Amphenol corporation (a manufacturer of electrical connectors) merged with Bunker Ramo. |
Amphenol Circular Slide Rule & RF Smith Chart Made in USA by Bunker Ramo, Amphenol RF Division, Danbury, Connecticutt. 9.25in [23.5cm] Diameter Plastic Film Front Scale: D, ( C, CI,A, K, L, T Cot, S Cos, ST) Back: Radio Frequency Smith Chart (with cursor on cursor): Wavelength toward Generator, Wavelength toward Load (Angle of Reflection, Negative Reactance Component, Positive Reactance Component, Resistance Component) Cursor Scales: Voltage or Current Limits, Voltage or Current Ratio, Attenuation Dissipation Reflection, IDB Loss, Toward Generator, Toward Load
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Science Spectrum Octal-Decimal Slide Rule Calculator REF |
Science Spectrum Octal-Decimal Slide Rule Calculator 1969 Made in USA by Science Spectrum, Inc, Santa Barbara, Calif. Designed by Phillp J. Wyatt, Albert S. Trundle, Judith B. Bruckner Patent Filed in 1969: Issued April 4, 1972, US 3,654,437 8in Diameter Vinyl Plastic disk. Note: This design is similar to the single Gilson circular slide rule with three cursor arms. Back Scale: (Octal: CO, C20) (Decimal: D spiral scale) Archive - Photo by David Sweetman collection, Nevada Company Logo, 1969 Sales Brochures (236 Kb PDF), 1972 Patent (1MB PDF) |
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Science Spectrum Hexa-Decimal Slide Rule Calculator REF |
Science Spectrum Hexa-Decimal Slide Rule Calculator 1969 Made in USA by Science Spectrum, Inc, Santa Barbara, Calif. Designed by Phillp J. Wyatt, Albert S. Trundle, Judith B. Bruckner Patent Issued 1972, Filed in 1969: US 3,654,438 8in Diameter Vinyl Plastic disk. Note: This design is similar to the single Gilson circular slide rule with three cursor arms. Front Scale: (Octal: CH, CIH, AH, LH) (Decimal:C, CI A, L ) ( 16H: Decimal Powers of 10H(=16D) Scale) Back Scale: (Octal: CH ) (Decimal: D spiral scale) Archive - Photo by David Sweetman collection, Nevada Company logo, 1969 Sales Brochures (236 Kb PDF), 1972 Patent (1Mb PDF) |
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Curtis L-M Rule, Frequency Response Calculator 1953 ISRM 14.04.30.01 |
Curtis L-M , Frequency Response Calculator Made in USA. Designed by Emory C. Curtis ©1953. Construction: 6-1/4 in Diameter Disks. 3 plastic disk with paper scales. Front Scale: Frequency, Frequencing Ratio, Damping Ratio (Xm/Xo, Phase Angle Degrees) Back Scale: Decibels, Aplitude Ratio, Damping Ratio, (Mp, Amplitude Deviation, Formulae) Gift of Ellen Emmerich, Munich, Germany, in memory of her father Ben Emmerich. Ellen Emmerich, his daughter, writes: "A friend of my father's in Minneapolis says: 'The slide rule you have is used to calculate the frequency response of control systems. Your Dad might have used it in his work on the VJ101. The graph on the bottom view is a Bode plot of a second order system. The slide rule would allow you to enter the damping ratio of the system and the trequency with which the system was being driven; and it woult tell you the ratio of the system output to its input. Examples of second order systems would be a spring suspended from a coiled spring. Another would be the servo actuators we used on the VJ101 to position the engine throttles.'" |
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Fearns Int'l Unit Conversions Calculator ISRM 23.04.11.02 Ted Baumen.was an immigrant from Holland who came across the Atlantic in 1953 on the USS United States. He studyied to become an electrical engineer and ultimately worked for a large aerospace and building services company in the US and Canada. Throughout his studies and his career, he used many slide rules for both mathematical calculations and US-Metric conversions. Continued |
Fearns International Unit Conversions (S.I. to MKS) Calculator Made in England by Fearns Calculators, Oakfield Drive, Whickham, Newcastle-U-Tyne, England. UK 5 in Diameter 0.25 thick Plastic Front Scale: Length, Area, Volume, Mass, Force, Velocity Back Scale: Energy, Density, Pressure, Powr, Volume Flow, Heat Flow. Original Owner:Ted Baumen (c1933- ) Gifted by Ted Baumen Jr. and Dawn Baumen.of University Park, Florida. Cont'dHe was part of a team that worked on the electro-mechanical interface for the CF104 Fighter (built in Canada by Canadair under license from Lockheed) which was a key element of the autopilot and auto pitch control systems. When Ted retired, he passed on his slide rules to his son, Ted Jr. a mechanical engineer, who had an interest in the elegance of these analog devices. At that time, mathematical calculations were becoming much easier to do by calculators, however, slide rules for US-Metric conversions remained very helpful (especially, in the absence of an on-line search tool to look up conversion factors). Ted jr. recalls: "I remember my father commenting that the slide rules gave him a more visual sense of how calculations were done and an intuitive sense that the answer was correct. He fond of saying, 'no batteries required'". |
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Fearns A7 Universal Metric Converter ISRM 17.10.10.04 Instructions |
Fearns A7 Universal Metric Converter Made in England by Fearns Calculators, Dunston, Gateshead 11, UK 5-1/2 in Diameter Plastic Front Scale: Index (1-105), Metric (C) (Imperial (D)) &dec;F, °C Back: Instructions, Conversion Index, Abbreviations, S.I. Units, Notes Original Owner/Location: Brian C. Cunningham, Australia (has name on back of stock) Donated by Andrew (son) and Barbara (wife) Cunningham, Willagee, W.A., Australia. Brian C. Cunningham (1935-2013) was born in Port Pine, South Australia, Australia. His education commenced there and continued at the South Australian School of Mines where he gained his Diploma in Mining & Metallurgy. He became a Student Member of the Australian Institute of Mining & Metallurgy rising to a Fellow member. Brian started his career as a Metallurgical Cadet at the B.H.A.S. (Broken Hill Associated Smelters) in Port Pirie. He transferred to Hamersley Iron in Perth, Western Australia, the subsidiary company of Conzinc Rio Tinto Aus. where he became an Executive Officer of the Hamersley Iron Group. In Brian's studies and work his slide rules where used extensively. |
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Fearns A13 Circular Slide Rule REF |
Fearns A13 Circular Slide Rule Made in England by Fearnes Calculators, Dunston, Gateshead 11, UK 5-1/2 in Diameter Pasltic Front Scale: K, A (( B, C,) D, Log, Sin Tan) Back: Instructions, Conversion Index, Abbreviations, S.I. Units, Notes Scan provided by Michael Syphers of Illinos. His website is Following The Rules.. | ||||
Mear Helical Spring Design Computer ISRM 13.00.00.71 |
Mear Helical Spring Design Computer Made (1977) by M.H. Mear & Co. Huddersfield, England for Associated Spring Corp (ASC) Note: Five coaxial disks 10mm thk 15cm dia Note: Mear purchased Fearns. In 2023 Mear stopped production on circular slide rules. Front Scale - Stress Calculator Load, Spring Index, Ratio of Sides, Mean Dia (Dia of Wire, No.Coils (Deflection, Correction Factor)) Back Scale - Rate, Load and Deflection Calculator Load, Spring Index, Ratio of Sides, Mean Dia (Dia of Wire, No.Coils (Stress, Modulas of Rigidity)) Donated by Jack Rababeh, Senior Engineer at ASC |
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Mear Comprehensive Conversion Calculator ISRM 13.00.00.06 |
Mear Comprehensive Conversion Calculator. 1974 Made (1974) by M.H. Mear & Co. Huddersfield, England for Johnston Pumps, Glendora, California. Note: Two coaxial disks and cursor, 5mm thk Note: Mear purchased Fearns. In 2023 Mear stopped production on circular slide rules. Front Scale: Thermal Conductance, Heat and Power, Length, Area, Flow and Volume, Velocity, Pressure and Strees, Temperature. Back Scale: Viscosity & DensityConversion, Conversion Factors. |
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Davis Instruments T-S-D Computer ISRM 14.07.02.96 |
Davis Instruments T-S-D Computer Made in USA by Davis Instruments Corp., Hayward, CA. 6in Diameter Plastic Front Scale (C&D scale): DISTANCE: Nautical or Statute Miles, KM or Yards (TIME: Minutes, Hours) SPEED Back: Instructions Gift Of Ed G. Millis, Dallas, Texas. Ed Millis was at TI while the electronic 'slide rule' calculator was developed and is good friends with Jerry Merryman, the designer of the first calculator in 1967. Ed has also written a book on hobbies Hither, Thither and Yawn. Ed is a generous donor of over a hundred slide rules, calculators and ephemera to ISRM. |
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Miller Dial Circular Slide Rule ISRM 13.02.23.01 |
Miller Dial Circular Slide Rule Made in USA. Data Charts by Miller Dial,El Monte, Calif. 6in Diameter PaperBoard Front Scale: D, ( C, CI, L, A, K) Back: Instructions |
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General Industrial Slide Rule 1959 ISRM 14.01.10.10 |
General Industrial Slide Rule 1959 Made in USA. by Slide-chart Corp. PERRYGRAF Corp, Maywood, Ill. for General Industrial Co., 1788 Montrose, Chicago 13, Ill. LOngbeach 1-5871 4in Diameter PaperBoard Front Scale: D, ( C ) Back: Instructions Gift of Bill Wehrend Collection, Palo Alto, California. |
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C-Thru S-96 Slide Rule 6in dia ISRM 04.09.27.01.D1 |
C-Thru S-96 Slide Rule 6in dia Made in USA - C-Thru Ruler Company, Hartford, Conn. Front Scale: K, D, ( C, B, A, CI, L) Back Scale: S, L, T Back: Instructions |
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C-Thru PS-69 Proportional Scale 5in dia ISRM 14.07.22.09 |
C-Thru PS-69 Proportional Scale 5in dia Made in USA - C-Thru Ruler Company, Hartford, Conn. Front Scale: Reproduction Size ( Size of Original, L) Percentage of Original Size, Number of Times of Reduction. Back: Blank Gift of Phillip Rodley, Upper Hutt, New Zealand. |
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REF SCA Circular Slide Rule |
SCA Circular Slide Rule (1973) Made in Australia by Slide Charts of Australia Front Scale (Extended) CI, C ( D, A, K, L) Back Scale Orginal Area (Conversion Factor, Converted Area) Scan provided by Cyril Catt. Australia |
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Ground Water Hydrology Computer ISRM 08.12.08.01 |
Ground Water Hydrology Computer - 4 coaxial disks 10mm thk Made in USA by Info, Inc Newton, MA (1967) for Layne Associates, Memphis, TN Front Scales: Transmissivity (T), Storativity (S), Time (t), Radius (r), factor (u), and Well Function of u [W(u)]. Back Scales: Well Function [W(u)], Transmissivity (T), Discharge (Q), Drawdown (s), and std. C, and D scales. Solves This Non-Equilibrium Equation for Ground Water: s = 114.6 Q W(u) / T; W(u) = e-u / u du; u = (1.87 r2 S) / (T t) Donated by the designer, N. Thomas Sheahan, Research Geologist, Layne Research Division, Memphis, TN Sheahan writes: "About 1,000 of the circular Ground Water Hydrology Calculator slide rules were produced... We had many of them printed with the names of the various associated Layne firms, but some were left blank to allow personalization. I continued to use this slide rule in the field and office from 1967 until the 1990s when I was finally able to get an HP-100LX, the first hand-held calculator that could solve this equation. Since then, I have had the slide rule as a wall decoration in my office until I retired this year (2008)". |
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Weems & Plath 105 Nautical Slide Rule ISRM 04.04.22.05 |
Weems & Plath 105 Nautical Slide Rule Made in USA by Weems & Plath, Annapolis, MD, 2002 Front Scale Distance Naut Miles, Yards (Speed, Time Min, Hrs ) Back: Instructions on use Owner: Mike Konshak's Personal instrument, used for USCG American Boating Course and Coastal Navigation traing. |
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Weems & Plath Tyler Slide Rule REF |
Weems & Plath Tyler Slide Rule 1966 Made in USA by Weems & Plath, Annapolis, MD, Front Scale: Unique layout for solving Propertions, Multiplication and Division, Squares and Square Roots, and Functions of Angles Back: Instructions on use Archive - Rod Lovette Collection, UK. Electronic Design magazine, V14-N13, May 2, 1966.Design Aids Column |
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Graphic Chemical Predictor ISRM 11.05.24.01 |
Graphic Chemical Predictor Made in USA by Dyna-slide Co. Chicago, Illinois - 8" diameter Front Scales - Chemical Compunds, Oxidization Equations, Reduction Equations Back Scale - Instructions |
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Mascot Vest Pocket Slide Rule - 1934 Made or distributed in USA by Tavella Sales Compan, 25 West Broadway, New York, N.Y. Note: Tavella Sales Co. also distributed the Gilson Midget at one time. Material 0.7mm[0.067in) thick 69mm[2.72in] diameter plastic disk Front Scale: L, D ( C, CI ) Back Scale: S, A, K, T |
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Mascot Vest Pocket Slide Rule - 1934 Made or distributed in USA by Tavella Sales Compan, 25 West Broadway, New York, N.Y. Note: Tavella Sales Co. also distributed the Gilson Midget at one time. Material 0.7mm[0.067in) thick 69mm[2.72in] diameter plastic disk Front Scale: L, D ( C, CI ) Back Scale: S, A, K, T Gift of Mr. Murphy of East Wanatchee, Washington |
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Cal-Co Patent Circular Slide Rule ISRM 13.08.11.01 Photos of Francis Donchi, with European Ford Capri, and with grandson Nicolai Donchi, la Brianza, Italy. |
Cal-Co Patent Circular Slide Rule Made in Italy. Outer stator disk is 6.5 cm [2.6 inch], inner disk is 5.5 cm. Country of origin based on 'SIN' being printed as 'SEN' and metric HP conversion gauge mark of '736'. Note: Appears to be painted/silkcreen on aluminum disks with brass hub. c1940 Front Scales: C ( D, A, K ) Back Scales: L, SEN 1, SEN 2, TG Note: Concentric Sine scales Donated by Nicolai Donchi, Monza, Italy in memory of his Grandfather Francis Donchi. This artifact was found in the house of his Grandparents. and was owned by his Grandfather. Francis Donchi (1917-1993). Born in August 17, 1917 in Paina Brianza in Lombardy (Italy) where he finished elementary school and for the next 7 years, helped his father, Francesco, in the fields. At 18 he started working in a textile company on the banks of the River Lambro (Monza river) living modestly. At age 22 he was drafted into the Italian Army where he served with honor for 4 years from 1939 to 1943. After WWII he met his wife, who was a girl from his own village. Francis received a 'gratitude of war' after a few years for a lung disease due to breathing the toxic smoke created by the war industries. Though partially invalid he began a quiet life in Carate Brianza (Lombardy) and to have a child that carries on the family name. Francis had a second job restoring furniture in his house, which had many tools of the trade and where this slide rule was discovered after his death at age 76. |
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Latt-Mayer S.A. 42-8125 Circular Slide Rule REF |
Latt-Mayer S.A. 42-8125 Circular Slide Rule Made by Latt-Mayer S.A., Rio De Janeiro. Approximately 5cm in diameter. Front Scale C (D) Back: Promotion of Latt-Mayer product line (Portugese) Archive - Photo by João Roberto Gabbardo collection, Brazil |
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US Army Signal Corps Psychrometric Calculator ML-322/UM REF |
US Army Signal Corps Psychrometric Calculator ML-322/UM Made in USA by Virginia Plak Company 1944 Front Scale: DP, VP, C2, C1, t' ( t-t', P, THETA) Back Scale: DP, VP, C2, C1, t' ( t-t', P, THETA)
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Cox Stadia Computer REF |
Cox Stadia Computer Made in USA by Perrygraf - design by W. & L.E. Gurley Front Scale: Difference of Elevation, Horizontal Difference Archive - Not in Collection |
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Hemmi 1001 Circular Slide Rule REF |
Hemmi 1001 Circular Slide Rule Made in Japan by Sun Hemmi Front Scale A, D( C, CI, B ) Back: TBD Archive - Not in Collection |
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Norton & Gregory Roto-Rule 3.5" dia REF |
Norton & Gregory Roto-Rule - 3.5 inch dia Made in England - Norton & Gregory, London -Pat Feb-12-1907 Front Scale : A, C, D, L Archive - Not in Collection Instruction Sheet 121Kb |
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Multor Currency Exchange REF C26 |
C26 Multor Currency Exchange Made in WestGermany - 3 color metal 8.8cm disk Front Scale D (C, A ) 1.17Mb |
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Emeloid - Proportional Reproduction Size Finder REF C22 |
Emeloid - Proportional Reproduction Size Finder Made by Emeloid Operations, Hillside, NJ 6in (15cm) Dia Plastic Film disc Front Scale Reproduction Size ( Size of Original) % of Original Size, # times reduced ) Donated by Jack Rababeh, Senior Engineer at ASC |
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Graphic - Percentage Calculator REF C23 |
Graphic - Percentage Calculator Made by Graphic Calculator Co., Barrington, Illinois - 1962 6in (15cm) Dia Plastic Film disc Front Scale Sales ( % of Sales) or Number ( Percent ) Donated by Jack Rababeh, Senior Engineer at ASC |
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Graphic - Profit Finder REF C25 |
Graphic - Profit Finder Made by Graphic Calculator Co., Chicago, Illinois - 1954 8in (20.2cm) Dia Plastic Film disc Front Scale # of Items, Selling Price ( Markup, Profit ) Donated by Jack Rababeh, Senior Engineer at ASC |
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Ahrend Construction Disk REF |
Ahrend Construction Disk Made in Netherlands by Ahrend Archive - Herman van Herwijnen's SR Catalogue |
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Watham - Profit Finder REF C24 |
Watham - Profit Finder Made by Watham of Chicago - 1962 5-1/2in (14cm) Dia cardboard disc Front Scale # of Items, Selling Price ( Markup, Profit ) Donated by Jack Rababeh, Senior Engineer at ASC |
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Gong Se He Ying - Metalworking ISRM 21.03.13.36 |
Gong Se He Ying - Metalworking calculator for Iron materials Made in China by Sheyang DALI Metal Factory Front Scale degree, meter, quantity, kilogram (Steel. Iron, cast, ball, flat steel, flat iron, flat cast) Back Scale SG, A [ B, T Cot, ST, Sin Cos ] D, DI |
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Educational Instruments Corona 1 REF |
Educational Instruments Corona 1 - c1965 Made in USA by Educational Instruments, Inc - 9cm Diam plastic Front Scale: C, D, R (= DI), A, K, L, S, T, ST Back: The back, which has a window to the front disk for more surface area for equations, contains a mine of information. 112 formulae; 2 trig tables, 41 conversion factors 6 series expansions, 2 numerical integration formulae 13 numerical constants, 72 integrals, 36 differentials Archive - Scan provided by Rod Lovette (UK) Collection |
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Lufkin Screw Thread Tap Drill Chart ISRM 18.07.18.01 |
Lufkin Screw Thread Tap Drill Chart Made in USA by Lufkin Rule Co. ©1935 Front Scale National Coarse (size of Tap, Threads per Inch, Size of Tap Drill) Back Scales: Screw Threads and tap drill sizes |
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Hutchinson Calculator No2 Gas Flow in Tubing ISRM 18.03.20.14 |
Hutchinson Calculator No2 Gas Flow in Tubing 1956 Made in USA by Robert M. Hutchinson, Houston, Texas. Formulae by Mueller Co. Decatur, Illinos Note: This is a 10" x 10" 6 page folder with instructions and a table. Front Scale D:Inches of Water, A:Cu.Ft.per Hour ( C:Length in feet, B:High Pressure, B':High Pressure, B:Low Pressure, B':Low Pressure, ) Cursor:Dividing Scale Belonged to Robert N. Curry. Gifted by his friend Alice Bowling of Louisville, Kentucky. Robert N. Curry was a 1949 graduate of Western Kentucky University. Bob was the head of Measurement for Texas Gas Transmission Corp and authored a book on Natural Gas processing Fundementals of Natural Gas Conditioning. He was former chairman of the AGA Transmission Measurement Committee. Several of his slide rules are currently in the ISRM galleries. |
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Edmunds Scientific Cal-Math Circular Slide Rule REF |
Edmunds Scientific Cal-Math Circular Slide Rule Made in USA, Distributed by Edmunds Scientific. Front Scale: D (C, K, A) Archive - Photo from the internet |
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Ericsson Proportion Calculator Slide Rule ISRM 13.00.00.87 |
Ericsson Proportion Calculator Slide Rule Made in USA, 4.75 inch dia . Possibly used for finance. Front Scale: 50 to 75 (10 +%, to, 10 -%) Based on the equation on inner dial: to= (3600•1000•n)/(C x P) |
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