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Held in the virtual world 2021

Review of the Annual Meeting, May 15, 2021

Our annual meeting this year, held as a Zoom online conference, featured updates on the health of our organization, five presentations on a variety of topics, and an auction of items primarily from the Wayne Wagner collection. Clark McCoy noted that as of May 15, 277 members had renewed for the year with 21 new members. He also noted that the Oughtred Society was in fine financial health with a significant budget set aside for our Educational Committee. Bob De Cesaris was nominated and elected to continue as President; Clark McCoy was nominated and elected to continue as Treasurer and Membership Secretary. It was noted that Otto van Poelje’s book, “The ALRO Catalogue” was available in Europe and that we would run ads in the JOS to help with generating interest in the US. The book features many colorful glossy photographs of ALRO slide rules, a Dutch manufacturer of slide rules, which primarily specialized in high quality circular rules from The Hague, Netherlands. One of the unique features of many ALRO rules is the attached metal case which not only protected the rule when used in the field, but also served as a convenient stand for desktop use. Excellent feedback was also received regarding the virtual IM2020 Meeting held last September and it was noted that all presentations from that meeting have been posted on YouTube and are available for viewing on the OS website. Many thanks to Jim Bready for recording the meeting and dividing it by presentation and to Ace Hoffman for posting each of the presentations to our site. It was also announced that sales of items on eBay from oughtred11 continue to be impacted by the Covid epidemic; plans are being made to begin selling again once the situation has clearly stabilized.

The first presentation, by Jim Bready, entitled “How Long is a Slide Rule?” featured a discussion of what length of slide rule makes sense with regards to precision and practicality. Jim investigated the 12.5, 25, and 50 cm long slide rules, since these were the most common lengths, and speculated that these lengths were based not on advantages in mathematical precision, but on convenience in use. He further stated that a typical 25 cm slide rule contained ‘good enough’ precision for most engineering projects, with 4 significant digits at the left end of the scale and 3 significant digits at the right end. A rule would need to be 10 times as long as a typical 25 cm rule to increase the significant digits by only 1 across the rule, hence he questioned, where is the necessity to create rules that are 2, 3, 4 or 5X in length as that of a 25 cm rule? He noted that the only practical value of a 50 cm desk rule was to enable the user to more easily read the the scales and did not contribute to much increased precision. He further stated that the 25 cm rule would the ideal choice for field use, whereas a 50 cm rule would be mostly confined to office or desk use and that anything longer than 2X or shorter than 10X the length of a 25 cm rule would not add much to the mathermatical precision of the rule.

The next presentation, “Demonstration of a Computer Reproduction of Kaufmann’s Posographe” was a description and computer modeling demonstration of the posographe by Ace Hoffman. Ace’s goal was to understand how the designer had developed this interesting device which took input from the user for either indoor or outdoor photos and output information on exposure time. Some of the input variables noted are ‘state of the sky’, ‘distance to object’, ‘lighting’, and of course, ‘aperature’. To analyze the device fully, Ace purchased an example from eBay and proceeded to develop a computer model of the inner workings of the device, which is now available for review. Nathan Zeldes, who was in attendance, noted that when he wrote his piece on this device, he had spoken to descendants of the inventor and that Kaufmann had used direct observation and some trial and error to arrive at the final design of this most intriguing device.

Mike Konshak then proceeded to update the attendees with some of the latest initiatives out of the International Slide Rule Museum. Mike noted that the ISRM was founded in 2003, initially with the goal of collecting specimens, but the focus has changed to preservation. In the process of outlining important pieces for preservation, Mike realized that it was also important to preserve ‘the papers’ that accompany a rule, including instruction booklets and other related ephemera. Mike began collecting copies of manuals, and requesting copies or scans of manuals from other collectors which he scanned and then cleaned up by removing any user writing or other marks and reprinting them. His reprints include collections of manuals by manufacturer, by country of manufacture, or by language. Mike is currently up to a total of 13 different books of reprints, all available on Amazon each for $20 paperback, $28 hardback.

The fourth presentation was entitled “Russian Slide Rule Design Standards, GOST 5161” and given by Karl Kleine. Karl reviewed the Soviet standard GOST (GOsudarstvennyy STandart, or government standard, similar to ANSI Standards [American National Standards Institute] in the US) for general purpose slide rules. He covered many details of the standards for different models, different lengths and various scale arrangements that would ensure that the final product was of high quality, durability, and accuracy. The standards also defined exact scale labeling, engraving of tick marks and of standard gauge points. In addition, there were specifications for the specific materials that were used for the body and for the scales, including those for type of wood, celluloid, cursor springs and glass.

The fifth and final presentation by Mike Syphers covered a transitional model of the Keuffel and Esser model 4092 slide rule where the K-scale is added to the very bottom of the scale arrangement, instead of the normal configuration where the K-scale is located at the very top. Discussion among the attendees confirmed that no other member present had ever seen that scale arrangement and K&E specialist Clark McCoy speculated that this was likely a single run of perhaps several hundred rules that occurred in the 1923-24 time frame.

The meeting concluded with our traditional auction, consisting of 25 items from the Wayne Wagner collection and one item from the Bob Otnes collection. A list of the top items that were sold at our meeting follows:

Fuller Calculator, Type 1, exc cond $400
Thacher Calculator, Model 4012 $320
Pickett N4-ES 4-foot classroom rule $275
Stephenson-Pfahl Hardenability SR $150
K&E Catalog, 1962 $ 96
FXR Smith Chart $ 65
Gilson Binary slide rule, NIB $ 60
Otis King Model K, exc cond $ 60

Here are the URLs for videos for each OS2021 presentation:

1. The meeting assembles with lots of chat
2. Welcome and introductions
3. Jim Bready - How Long is a Slide Rule?

4. Ace Hoffman - Animated Posographe Simulation

5. Mike Konshak - Slide Rule Instruction Manual Reprints

6. Chat During the Break
7. Karl Kleine - Russian Slide Rule Design Standards

8. Mike Syphers - A Transitional K&E 4092 Slide Rule

9. Bob De Cesaris - Oughtred Society Annual Business Meeting
       https://youtu.be/NkiJOJMZPeg ZPeg

Link to the previous Oughtred Society meeting (2020; held virtually with the Int'l society):


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last modified September 07, 2021