Keuffel & Esser  Mannheim 4031-4041-4051

The 20 inches long Mannheim 4051-5 model was produced in the United States between 1925 and 1938. The 10 inches long Mannheim 4041 was produced from 1900 to 1942. The 5 inches Mannheim 4031 was produced from 1900 until 1940 (The production years are assumed based in the years these rules appear in the K&E Catalogs). 

These models were fabricated form wood covered with white celluloid where scales were engraved. On the front side they had the A-B and C-D scales and at the back of the slider the S. L and T scales. These model also has on the edges centimeters and inches scales. The 4051-5 and 4031 models were produced with all glass and framed cursors, while the 4041 was produced with the metallic, all-glass and framed cursors. The 4041-3 model was also fabricated with a special metallic decimal keeper cursor. 

I have include in this group the 5 inches pocket 4098A model, with the same scales as the 4041, including the centimeters - inches scales. It was produced in the United States from 1936 to 1949, and it was fabricated from solid Xylonite (a strong thermoplastic celluloid with and ivory look) where the scales were engraved. Its frame less cursor was fabricated with transparent Xylonite nailed to plastic ends. The fabrications dates of these rule can be estimated when they have a serial number (if any) or depending the kind of cursor they have. The estimated fabrications years of the models shown below are, in the same order as in the pictures:

• 4051- 5 (20 in, wired framed cursor): 1930-1935. Original price: $ 17.00 ($ 355.00 in 2023 USD)

• 4041-3 (10 in, wired framed cursor): 1938-1943. Original price: $ 7.50 ($161 in 2023 USD)

• 4041-3 (10 in, all glass cursor): 1920-1925. Original price: $ 6.50 ($ 109.00 in 2023 USD)

• 4041-3 (10 in. metallic frame cursor): 1901-1906. Original price: $ 4.50 ($ 159.00 in 2023 USD)

• 4031 (5 in all glass cursor): 1910-1922. Original price: $ 4.50 ($ 132.00 in 2023 USD)

• 4098-A (5 in, all plastic cursor); 1940 - 1945. Original price: $ 2.00 ($ 41.00 in 2023 USD)

What kind of operations is possible to perform with these models. A skillful user can solve problems 1- 13, 18 - 20, 24 - 27 and 29 - 33 in the next test: 

Click on the next links to see professional panoramic pictures of the 4041 and 4051 models. 

Mannheim 4051

https://www.sliderulemuseum.com/KE/KE_4051-5_20in_Mannheim_BelongedToJosephJGraf.jpg 

Mannheim 4041

https://www.sliderulemuseum.com/KE/KE_4041_AllGlassCursor_Lot36X_GiftOfEdMillis.jpg

https://www.sliderulemuseum.com/KE/KE_4041_Lot211_c1901_MissingLens_GiftOfNickKrantz.jpg

https://www.sliderulemuseum.com/KE/KE_N4041_sn637284_c1956_GiftOfNormaTanner.jpg 

Mannheim 4031

https://www.sliderulemuseum.com/KE/P109_KE_4031_95888.jpg

https://www.sliderulemuseum.com/KE/KE_4031_Mannheim_PaulTarantoloCollection.jpg

References:

• 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