Keuffel & Esser Mannheim 4161-3 & 4161-1

The Mannheim 4161 family was manufactured in the United States from 1952 to 1972. It was fabricated with Ivorite, (Acrylonitrile Butadiene Styrene (ABS) CYCOLAC™ Resin ), a smooth, white, and long wearing plastic. Scales were printed on the Ivorite, and the single glass metallic frame indicator was screwed to plastic ends . It was an advanced version of the 4053 model, with the main difference that the 4161 had the folded scales DF-CF in the position the A-B scales had on the 4053. The A-B scales were relocated: A at the bottom of the front face, and B at the back of the slider, but labeled C. In 1967 the 4161-3 and the 4161-1 were re-named Jet Math Group, and the model numbers changed to 68-1576 and 68-1581 respectively (1).

The scales on the 4161-3 model were: inches- K DF [CF L CI C] D A -centimetres on the front face, and [T ST S C] on the back of the slider. There were units conversion tables on the back side of the rule.

The original prices for these models in 1962 were: $ 11.00 for the 10" 68-1576 ($109.58  in 2023 USD), and $7.50 for the 5" 68-1581 ($74.71 in 2023 USD)

References:

(1). McCoy, Clark: K&E 1962 Catalog, The Modern Polyphase Group. http://www.mccoys-kecatalogs.com/KECatalogs/1962/1962kecatp21.htm 

• 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