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The Oughtred Society was founded in 1991 by a group of slide rule collectors and is dedicated to the preservation and history of slide rules and other calculating instruments. Over the past three decades it has evolved to an international organization with members in 20 countries. It is noted for its highly acclaimed Journal of the Oughtred Society, published twice annually. The Society is a non-profit educational organization. Society goals include the dissemination and sharing of information and encouragement for collectors. We are affiliated with organizations in the United Kingdom, Germany, The Netherlands and Italy. Our activities are carried out by members who volunteer to do various tasks and projects. Membership is open to anyone. Click "Membership" in the left navigation menu for more information about member activities and benefits.


    Message from Bob De Cesaris:

    Subject: Announcing our Virtual Oughtred Society Annual Meeting for 2024 to be held on Saturday, June 15 via ZOOM link

    Our Oughtred Society by-laws require the Society to have at least one meeting annually where election of officers and other business of the Society is discussed by the Board and the Society’s members. In the past, pre-Covid, these meetings were held face-to-face in Palo Alto and then, Las Vegas, and most recently virtually through ZOOM.

    Since IM2024 is being hosted by our colleagues at the Kring this year in September, the Oughtred Society will be holding the Annual Meeting separately on June 15 from 10AM to 2PM. As always, all members of the Oughtred Society are invited; please mark your calendars and plan to attend.

    Topic: Oughtred Society 2024 Annual Meeting
    Time: Jun 15, 2024 10:00 AM Pacific Time (US and Canada)

    The first hour will be dedicated to our business meeting, including membership and financial updates, and our annual election of officers. The business meeting part of the Annual Meeting traditionally takes place at 1 or 2PM PDT but we wanted to give our international members the opportunity to also participate, hence we will kick off the meeting with the business discussion (10AM PDT, 1PM EDT, 6PM BST, 7PM CEST) for the first hour. This year, I would like to spend some very important time encouraging more activity from the membership to assist with the Journal, with listing of collections in the archives, with the sale of member collections, and other activities that have been part of our Society over the years. We must increase our OS officer ‘bench strength’ to ensure our organization’s future health since currently we are running quite lean on bandwidth and the concern remains acute that if any one of the current key officers should fall ill or not be able to continue, our organization would certainly be at risk.

    After the business section, we would like to invite members to give 10-to-15-presentations on a favorite topic and also continue our recent very successful ‘favorite/special slide rule mini-presentations/discussions’ where we will give each volunteer speaker 5-10 minutes to present a special, unusual, or favorite piece and take questions on it. The amount of time for the latter will depend on the response for the 10-15-minute presentations. We do not want to in any way take from the IM2024 agenda, hence the goal will to keep our discussions very informal and interactive and the more formal presentations should be saved for IM2024 in September.

    Thank you. We hope to see you at our Oughtred Society Annual Meeting this year.

    Oughtred Society Board of Directors

  • Jorge Fabregas Zazza
    Sept. 5, 1961 - April 5, 2024

    Born in Genazzano, Italy, the family moved to Catalonia, and Jorge becomes responsible for maintenance and spare parts in the electronics industry.

    Around 2004, laryngeal cancer disconnects him from the working world. Having learned about slide rules from his father, as entertainment he begins to buy them, especially the ones from Faber Castell.

    At the same time he buys, he takes pictures of these, with the idea of creating a Spanish-speaking website. And the sale also appears from there, to pay for his collection, the website, etc. On March 10, 2006, his project is released to the public. Soon he also creates the “Amigos de las Reglas de Cálculo” forum, ARC, to share comments, knowledge and images with other collectors.

    He now has his own server system and then hosts another of ARC's websites, photocalcul.com. Over the years, with more knowledge and means, he decides to re-photograph his collection in high definition, leaving today's website, which also includes the “ARC Presentations”, the Encyclopaedia on slide rules, and the list of slide rules. of Spanish origin. Upon the death of Daniel Toussaint, he rescues and preserves his website, linearis.org. Between 2009 and 2019 he attends international collectors' meetings in Europe.

    There is little more left to mention about this great friend, with a calm and attentive attitude, always generous and willing to help. Rest in peace, Jorge. -- Jose G. Fernández, April 23, 2024

  • OS Fellowship 2023

    At the recent International Meeting (IM2023) the Chairman of the OS Awards Committee, Prof. Karl Kleine, announced that a Fellowship had been awarded to Jacques Perregaux. Later the full story will appear on the OS Awards webpage.
    Jacques Perregaux

  •  Two Important New (2022) e-Books!

  • Thanks to Jose G. Fernández collectors can now download free-of-charge English and/or Spanish translations of the important Rechenschieber im Wandel der Zeit (Slide Rules through Time) book published in 2009 by Guus Craenen. This book charts the development and evolution of the slide rule from 1787 to 1905. Click on the image of the front cover to download either of the translations.

  •  New (2022) Book:

  • The Oughtred Society is pleased to announce the publication of a new book: " A Closer Look At Mechanical Air Navigation Computers". This 197 page book describes the operation and principals behind these unique historical devices. Many detailed images, drawings and examples are given. Numerous devices are described. Collectors, pilots and others interested in aviation should find this work to be of great interest. Klaus Petzgold, a 30 year chief pilot, flight instructor and teacher, is the author of this fine book. A limited supply of this book is available from the Oughtred Society at a cost of $35 plus $8.50 shipping.

  •  View Bob Otnes’ collection

    Memorable collections can be big or small. However, the collection of OS founding member Bob Otnes (1932-2019) was truly legendary. OS volunteers are working hard to record for future reference in the Archive of Collections the many, many items that made up Bob’s collection. It will take a while to complete the work but already a major tranche of the collection can be viewed HERE.

  • Stempunked!

    Richard Blake has been expanding his efforts to bring an introduction to slide rules program to schools and libraries in his local area. He has posted the presentation file for his educational program online here: https://www.stempunked.com/when-slide-rules-ruled. If you are interested in duplicating his efforts in your local area, click the link under the heading Presentation Materials.

  • Did You Notice?

    Reassuringly the OS website now boasts an HTTPS secure “padlock”. The upgraded security level (now encrypted SSL) should make NO difference to the performance but it does ensure the site is much more secure for our visitors

  • F-C Book Updated

  • After going digital 15 months ago and over 1,000 free downloads it was time for an update. Edition V 8.1 of Peter Holland’s definitive book in English and German on every slide rule made by A.W. Faber and A.W. Faber-Castell is now free to download from here

  • Find Every Electro!

  • Rod Lovett’s latest search facility makes it easy to access the extensive data on Electro types compiled by Bob Adams over many years. Take a look and find every known specialist Electro and Electronic slide rule – try it out here

  • The new edition of the Journal of the Oughtred Society is out! (See below for sample page and TOC images!)

  • Calling all authors! The Oughtred Society is preparing the 2024 Journal issues, and is looking for some good articles! Contact Journal editor Jim Bready with your proposal, and see The Journal of the Oughtred Society web page for more information and to download the JOS Guidelines for Authors.

  • Book review by Michael Konshak:

    Book Review of Volume 1 of the 24+ intended volumes (22 currently available), about each major manufacturer of slide rules. The volumes are available on Amazon ($27.95 per hardback or $19.95 per paperback). A portion of each sale is donated to the ISRM (International Slide Rule Museum). Each volume is ~550 printed pages.

    Reviewer Michael Konshak is a retired mechanical engineer and the curator of the International Slide Rule Museum since 2003. He is preserving the 50- to 100-year-old slide rule manuals in the Slide Rule Instruction Library Series. Michael has been a long-time contributor to the Oughtred Society.

  • Free On-Line BOOK: The Oughtred Society is proud to announce the publication of LONG-SCALE SLIDE RULES in LIFE-SIZE IMAGES by Otto E. van Poelje, dedicated to the memory of our Oughtred Society fellow collector & long-scale slide rule connoisseur Edwin Chamberlain (18-10-2017)

  • Archive of Collections. New Collections added to this Archive. The first collection in this Archive was that of the late Tom Wyman. We now have five collections featured; items from the collections of Paul Tarantolo, Louis Gotlib, Richard Davis, Cliff Frohlich and Thomas Wyman. All the collections continue to grow under the direction and efforts of Clark McCoy, Rod Lovett, Ted Hume and Richard Davis. We invite you to view this new Archive of Collections and consider having us post your collection to the OS website for posterity.

  • The Oughtred Society is proud to publish The Inventor of the CURTA Calculator an autobiography. This book is the story of the remarkable life of the inventor of this ingenious device, how he started in his father's mechanical office machine company in Vienna, eventually running the company himself, designing the Curta and becoming embroiled in WWII as a prisoner in a Nazi concentration camp and finally the difficulties of setting up full production after the war in Liechtenstein. Additional material written by the late Tom Wyman and Dr. Robert Otnes is included.

  • Pencil Slide Rules: A new publication introduced earlier in the year by the Oughtred Society: Pencil Slide Rules and their Successors, The Calculator Pen and Pentop Computers is a collection of articles that admirably covers this subject! This monograph is authored and edited by one of our Oughtred Society founders, Rodger Shepherd. This publication is now available for sale on our website.

  • JOS DVD is available for sale, containing 26 years of the Journal of the Oughtred Society in PDF format. OS members and non-members(individuals and institutions) may purchase the DVD by going to the Journal page and paying for the disk via Paypal.

  • A Search Facility for the Journal of The Oughtred Society awaits your use.
    (See Journal Search in main menu at left.) This new Search Facility displays high resolution PDFs of Journal articles. You may search by several methods -- author, title, keyword, or for any word that appears in any article, or for all articles in a given year, etc.The search facility was created by Rod Lovett.

  • Request for Articles for the 2024 and 2025 Journals. Be a contributing author and share your knowledge and interests. For ideas and inspiration, read "Yes, You Can Write for the Journal of the Oughtred Society" (82KB pdf).
  • Current Journal of the Oughtred Society

    JOS 2023-32-2 Cover JOS 2023-32-2 TOC JOS 2023-32-2 Sample Page
    Cover                        Table Of Contents           Sample Page

General Information





Publications of the Oughtred Society

Order Details for
All Publications

Slide Rules Through Time 1787 - 1905

JOS Book
Mechanical Air Navigation Computers
By Klaus Petzgold

26 years on one disk


Specialized Slide Rules Cover
Specialized Slide Rules
for Electronic Engineers

The Inventor of the CURTA Calculator
The Inventor of the
CURTA Calculator

Pencil Slide Rule Book
Pencil Slide Rules

The Slide Rule Technical Cultural Heritage
by IJzebrand Schuitema

K&E Slide Rule History
K&E Slide Rule History

Slide Rule Reference Manual
Slide Rule Reference Manual
2nd Edition

Pocketbook of Gauge Marks
Pocketbook of Gauge Marks
2nd Edition


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last modified June 15, 2024