Keuffel & Esser 4092 Log Log Duplex
The duplex K&E 4092 family was produced in the United States from 1909 to 1938. The 4092 family was fabricated with mahogany coated with white celluloid and held together with L-shaped metal end pieces. The scales were machine engraved on the celluloid. This rule had changes in its scales and cursor used during the production years.
From 1909 to 1921 the scales were: A [ B, S, C ] D on the front face, and LL1, LL2, LL3 [ C, T, CI ] D, L on the back face. These rules came first with the metallic column cursor (1909-1915), and then was changed to all glass cursor (1916)
From 1922 to 1925 the scales were: LL0, A [ B, S, T, C ] LL3, LL2, LL1 on the front face, and DF [ CF, CIF, CI, C ] D, L on the back face. These rules came with the all glass cursor.
From 1926 to 1938 the scales were: LL0, A [ B, S, T, C ] LL3, LL2, LL1 on the front face, and K, DF [ CF, CIF, CI, C ] D, L on the back face. These rules first came with the all glass cursor (1926-1931), but in 1932 this cursor was improved with flanges covering the corner of the glass. In 1934 this frame less cursor was replaced by the improved wire framed cursor.
The 4092 family was produced in two sizes: N4092-5 the 20 inches long model (1922-1938), and the 12 inches long version: 4092 (1909-1921), 4092-3 (1922-1925), and N4092-3 (1926-1938).
According with the serial number on the rules in my collection, these were fabricated between 1926 and 1936. Two of them seem to have the original cursors but the oldest one, fabricated by 1926, has the most modern cursor. Possibly the owner replaced when the original deteriorated. In the 1930 price catalog, the N4092-5 has a price of $24.50 ($ 441.35 in 2023 USD), and the N4092-3 a price of $10.85 ($195.46 in 2023 USD)
The 4092 family was a rule designed for Engineering and Science advanced applications. The 4092-5 in my collection is labeled "US-CEC", acronym corresponding to the United States Civil Engineers Corps, the US Navy group responsible for executing and managing the planning, design, acquisition, construction, operation, and maintenance of the Navy's shore facilities In 1938 the 4092 family was discontinued and replaced by the 4080 family.
It is also known that the model 4092 was used by the famous Nuclear Physicist Dr Enrico Fermi (1), among other not identified rules, as shown in the next pictures:
The certainty that Dr Fermi used a 4092-3 was given by his grand-daughter Olivia (1). The 4092-3 had to be very useful for this brilliant nuclear physicist given that radioactive decay can be easily calculated with the LL scales:
Last minute acquisition : I got a 4092 fabricated between 1916 and 1921 (according with ISRM). Next are some picture of this new rule compared with the 1926 version in this collection. It can be seen the differences in scales and cursors between these to models:
The next operations can be performed by a skillful user of this rule, with two-three decimals precision
SlideRulePractice-2.pdfHere is a scan done by the International Slide Rule Museum of the 4092 family user manual:
M46_KE_TheLogLogDuplexSlideRule_N4092_1926.pdfClick on the next links to see professional panoramic pictures of the 4092 model:
References:
(1). Syphers, Michael: 9.8 Fermi's Golden (Slide) Rule. Vignette in Following the Rules (2019) http://followingtherules.info/fermis-golden-slide-rule
McCoy, Clark: Keuffel and Esser Catalog Site. K&E Catalogs and Price Lists for Slide Rules. http://www.mccoys-kecatalogs.com/KEmain.htm
This website is the most extensive digitla file of Keuffel and Esser product catalogs and price lists (prices shown here were taken from these lists) from 1881 until 1972. You can find also user manuals for many slide rule models, as well as other interesting brochures and materials.
Shawlee, Walter: Keuffel & Esser Co. Slide Rules. https://www.sphere.bc.ca/test/ke-sliderule.html
This website gives a good overview of models, and other interesting information and links