Smithsonian museums continue to be closed to support the effort to contain the spread of COVID-19. Read a message from our director, and check our website and social media for updates.

Keuffel & Esser 4097C Ever-There Simplex Slide Rule

Keuffel & Esser 4097C Ever-There Simplex Slide Rule

<< >>
Usage conditions apply
This five-inch solid Xylonite (celluloid) slide rule is one of several "Ever-There" pocket slide rules made by Keuffel & Esser. This line was noted for its light weight and small size. There are A, D, and K scales on the base, with B, CI, and C scales on one side of the slide and S, L, and T scales on the other side of the slide. The glass indicator has a metal frame, plastic edges, and metal screws. The top of the base is marked: KEUFFEL & ESSER CO. N.Y.; PAT. 1,875,927; MADE IN U.S.A. The right end of the slide is marked: < 4097C >.
The back of the slide rule has a scale of 5 inches divided to sixteenths of an inch and a scale of 13 centimeters divided to millimeters. The left ends of the back of the rule and of the back of the slide are marked with a serial number: 38642. The rule fits in a leather sheath marked: K&ECO.
After Adolf Keuffel applied for a patent on what became the Ever-There product line on October 29, 1930, K&E introduced this version of slide rule as model 4098 in 1931. It was renamed model 4097C in 1936 and was discontinued around 1951. With a case, it cost $4.15 in 1936 and $5.75 in 1949. By 1959, it was replaced by model 4153-1. Compare to 1981.0933.05 and 1981.0922.08. An instruction booklet, received separately, is 1981.0933.09.
This example was given to the museum by Myron R. Smith (1911–2007), an electronics engineer who used it in a long career at Collins Radio in Cedar Rapids, Ia., then at Honeywell in Minneapolis, and then at Honeywell in Seattle. Smith used the rule to solve problems relating to the testing of broadcast equipment, the design of electronic temperature controls, the design of power transformers, and corporate management.
References: Adolf W. Keuffel, "Slide Rule" (U.S. Patent 1,875,927 issued September 6, 1932); Bob Otnes, "Adolf Keuffel and the Later K&E Slide Rules," Journal of the Oughtred Society 8, no. 1 (1999): 37–38; K&E Slide Rules and Calculating Instruments (New York, 1931), 17; Catalogue of Keuffel & Esser Co., 38th ed. (New York, 1936), 324; K&E Price List Applying to the 41st Edition Catalog (New York, 1949), 32; K&E Price List Applying to the 41st Edition Catalog (New York, 1951), 35; K&E Price List Applying to the 42nd Edition Catalog (New York, 1959), 73; accession file.
Currently not on view
Object Name
calculating rule
slide rule
date made
Keuffel & Esser Co.
place made
United States: New Jersey, Hoboken
Physical Description
glass (cursor material)
plastic (overall material)
metal (part material)
overall:.6 cm x 16.3 cm x 4.1 cm; 1/4 in x 6 13/32 in x 1 5/8 in
ID Number
accession number
catalog number
Credit Line
Gift of Myron R. Smith
Rule, Calculating
Engineering, Electrical
See more items in
Medicine and Science: Mathematics
Science & Mathematics
Slide Rules
Data Source
National Museum of American History
Nominate this object for photography.   

Our collection database is a work in progress. We may update this record based on further research and review. Learn more about our approach to sharing our collection online.

If you would like to know how you can use content on this page, see the Smithsonian's Terms of Use. If you need to request an image for publication or other use, please visit Rights and Reproductions.


I have the same slide rule, except the right end of mine is marked 4097B. Per your description it would have been manufactured before 1936. My father, Oscar Klein, used the slide rule when he was a student at New York University circa 1935. He was drafted into the U.S. Army in 1941 prior to Pearl Harbor. He qualified for Officers' Candidate School and served as a Second Lieutenant in the Signal Corps 1942-1945 including 18 months overseas in Europe. He would have continued to use the slide rule while in the Signal Corps.

Note: Comment submission on our collection pages is temporarily unavailable. Please check back soon!

If you have a question or require a personal response, please visit our FAQ or contact page.