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New Rules!		 Reference Material Some History of the Slide Rule Site Tips
Vignettes 44 blog-like articles and stories about slide rules, calculations, and collecting
Last Update Vignette Title Abstract
2025 Jun 28 K+E Mystery Rules Update The earliest date for these rules of mystery just got a little earlier.
2025 Feb 20 America’s Earliest Part II American-made slide rules before Palmer’s Computing Scale? Enter the Belcher Brothers – and Kutz.
2025 Feb 19 Gauging and Excise Tax Slide Rules Ever wonder how to calculate the amount of liquid in that funny-shaped whisky barrel?
2025 Jan 15 Addition and Subtraction Logarithms High precision calculations – including addition and subtraction – using logarithms and (with less precision) slide rules.
2024 Dec 01 Stadia Rules Surveyors in the field and office used special slide rules with special trigonometric scales.
2024 Oct 30 The Pickett Deci-Keepers Getting the decimal point in the right location often plauges new slide rule users. Pickett came to the rescue with their Deci-Keeper scales.
2024 Oct 23 Rhumb Line Distance and Course Computer Find your bearing and set your course with this circular device, then compute the distance along the rhumb line before you set sail.
2024 Aug 29 Slide Rules for the Sikes Hydrometer But, how much of that liquid in the barrel is actually alcohol? And, of course, how much tax should be collected?
2024 Aug 18 Power Rules Log-Log scales are used for raising numbers to arbitrary powers. Their scales and use are explained.
2024 Jul 14 The French Connection to a Mystery Rule The scales found on a K&E Mystery rule are the American version of the French Beghin rule.
2024 Jul 10 Kolesch Rules This New York City company sold German import slide rules, including some with special scales.
2024 Jul 09 The Aver-O-Matic Patented and produced by a young Colorado entrepreneur, this device can calculate the average of up to 10 numbers as well as compute scores of multi-problem exams, based upon the number missed.
2024 Jun 17 Scale Wars The K&E Duplex rule introduced in the 1890s was a major improvement to the standard Mannheim. How did other makers react?
2024 May 26 The Acu-Rule from Wabash How did a Wabash, Indiana, school supply company come to sell Acu-Rule slide rules, while Lawrence Engineering was making similar items just down the road?
2024 Mar 25 The Scofield Engineer’s Slide Rule With the help of Thacher, a bridge engineer delivers an inexpensive but powerful slide rule at the turn of the 19th century.
2024 Feb 05 Chicago Rules Chicago companies played a strong role in the development of US slide rules.
2024 Jan 17 American Favorite Part II Further study reveals new insights (to me) into the early K&E American, Favorite, and Mannheim brands.
2024 Jan 10 How Do You Byoutou? A WWII-era Hemmi slide rule was used to train junior officers in the basics of ballistics calculations, including how to lead moving targets.
2023 Dec 14 Gauging Electro Rules The electro rules were early specialty devices derived from the Mannheim design, and helped introduce log-log scales to modern slide rules.
2023 Sep 25 Thacher’s Calculating Instrument Thacher’s cylindrical ‘Calculating Instrument’ (patented 1881) was sold by K&E until the 1940s, yielding the accuracy of a 30-foot linear slide rule.
2023 Aug 11 Following the Balloons Essentially a stadia-type calculation, slide rules were used to compute meteorological parameters through sightings of pilot balloons in flight.
2023 Jun 27 Carpenters vs. Engineers Those folding 2-foot rules with brass slides and logarithmic scales – what are they and how do they differ?
2023 May 29 Dietzgen Rosenthal Nestler Prototype Online images of a $7 Dietzgen for sale just didn’t look right. A Nestler prototype version of Dietzgen’s update to their Rosenthal model was uncovered.
2023 Mar 10 America’s Earliest Slide Rule Palmer’s Computing Scale of 1843 is often given this title.
2022 Dec 23 Spring Calcs Eternal Besides illustrating several spring calculation slide rules of various manufacturers, the formulas used are also derived!
2022 Dec 10 Out of Proportions Determining ratios and performing proportions calculations are basic functions performed by a standard slide rule.
2022 Jun 20 Vector/Hyperbolic Calculations Imagine finding the tangent of a complex number. You really can do this. With a slide rule!
2021 Dec 12 Helical Slide Rules Accuracy is gained through helical curves on cylindrical surfaces – the Otis King and Fuller slide rules.
2021 Dec 05 The Early American Favorite Cleaning of a $10 slide rule reveals a fairly early K&E.
2021 Oct 03 Lt. Shaw’s 4097D A simple search for a common model uncovers a slide rule very likely owned by a major player in the construction of the first US nuclear warships, the U.S.S. Nautilus and the U.S.S. Enterprise.
2021 Oct 02 Rule Change 4092-3 A rare transitional scale arrangement for the K&E Model 4092-3 was just sitting in the collection all along.
2021 Aug 10 K+E Beginner’s Rules Keuffel and Esser sold slide rules designed for beginners almost from the beginning.
2021 Jul 01 An Early Home-Made Spring Calculation Slide Rule While slide rules for designing springs became available from the major makers around 1950, Baetzmann introduced this one almost a decade earlier.
2021 Jun 20 A K+E Rule of Mystery Certain K&E slide rules with no model number remain mysterious.
2021 May 15 British Thornton Special Scales Hard to get that last digit on your S/T scales when the values get close to one? The Thornton Sd/Td scales can help.
2021 May 01 Getting to the Root You know how to use A&D or B&C to find the square root of a number; but can you solve a quadratic equation on a slide rule?
2021 Mar 01 The Long and Short of It How the accuracy in calculations using logarithmic scales scales with scale length.
2021 Feb 08 Hemmi 153 Scales Now imagine finding the tangent of a complex number through the use of the Gudermannian function. Don’t worry, it’s all explained…
2021 Feb 06 A Boykin Discovery Can you only find significant slide rules online? It still pays to visit your local antique stores.
2021 Feb 05 Fermi’s Golden (Slide) Rule What slide rules did Enrico Fermi use? A family member gives us insight.
2021 Feb 04 Rules of Engravement Slide rules were used in the layout of newspapers and magazines in the last century.
2021 Feb 03 The Original 4083 Before the development of the vector slide rule 4083-3, the 1916 K&E model 4083 was an early 16-inch Duplex general purpose rule.
2021 Feb 02 Rules to the Moon Pickett earned their place in US space history with their lightweight metal slide rules.
2021 Feb 01 A Favorite Rule Everyone should have a slide rule that just feels right. The Faber-Castell Model 1/54, a finely-made general purpose Darmstadt rule, fits the bill.
Collection Photos
A chronological look at the slide rule collection		 Rule Makers
The collection, organized by manufacturers
Special Groupings

Subgroups, such as oldest, youngest,
most scales,
specialty slide rules, …
A Searchable Table of the entire collection A Data Sheet for each rule

Welcome!

This DataFrame-driven web site presents a personal collection of slide rules as well as other useful information about slide rules, their operation and use. Click the arrows (> and <) on each page or use your keyboard’s arrow keys to move between pages. Use the left navigation pane or the quick links on this page to go directly to a particular chapter or subject.
-Mike Syphers


About This Web Site About the Author
The Oughtred Society United Kingdom Slide Rule Circle International Slide Rule Museum
17 July 2025