Archive Record

  • Email This Page
  • Send Feedback
Title Keuffel & Esser Slide Rule Dates. Slide Rule Museum; Ed Chamberlain; Clark McCoy.
Object Name Documents
Catalog Number 2010.002.0025
Collection Keuffel & Esser Company Collection
Credit Museum Collections.
Scope & Content Reference record for research: digital record only. No folder.
Estimating Keuffel & Esser Slide Rule Dates.

Chart & text as found 2010 at: http://sliderulemuseum.com/SR_Dates.htm#KE

--------
Chart for Estimating Keuffel & Esser Slide Rule Dates.
Ed Chamberlain 12/27/00 [chart with text below - see image]

[on same webpage]

Here are some excerpts written by Clark McCoy:

Serial Numbers:

Serial numbers started in 1924 beginning with 0 and going through 999999 then rolling over to 0 again. There were three rollovers occurring in 1943-1944, 1954, and 1962. In general the production rate was about 70,000 rules per year until the 1950s. In the 1950s and it was over 100,000 per year. The 1960s had a production rate of about 100,000 per year for several years and tapering off in the 1970s ending at about 700000. In general it is safe to assume a linear production rate between the rollover dates particularly for the common types rules.

Serial numbers can be used to approximate the manufacture date of a given rule however not necessarily the sales date. The common rules were produced in regular batches but the specialty rules did not sell as well and a given batch of rules might stretch over several years. It is not uncommon to find rules in the 1960s in 68 xxxx series packaging but 4000 series model numbers on the rules. The Fuller and Thacher's slide rules had their own serial number systems.

Model Numbers: There were four different number series in the history of the slide rule line.
1881-1883 -The numbers 479-481 were used.

1887-1899 -The numbers 1740-1749 were used. There was little if no logic to these numbers.

1900-1961 -The numbers 4000-4199 were used. There were logical groupings of numbers and dash numbers were used to depict length variations of a given rule type. "N" was used as a prefix many times to denote some change in a given model. The use of the "N" prefix is not always consistent. Removal of the "N" prefix also indicated a variation in the model.

1962-1975 -The numbers were converted to a 68-xxxx number series. The dash number scheme for length variations was abandoned. There are numerous examples of 68 xxxx series numbers on retail boxes and the slide rule inside has the old 4000 series number on it. We are sure that this was in the early 1960s while they were working through old 4000 series stock.

Cursor Types: The cursors used on K&E slide rules evolved over the years. When they changed, all production of all models was switched over. There is a definite timeline to the cursor models.

Before 1906 - Slide rules either had no cursor, a brass chisel type cursor, or a metal framed glass cursor.

1913-1915 - A complex cursor that has been named the "column cursor" was introduced for duplex rules.

1915 - All slide rules were fitted with an all glass cursor. The first issue had metal end blocks.

1916-1933 - The metal cursor cursor blocks on the all glass cursor were replaced with plastic ones.

1933-1935 - The plastic cursor blocks were modified to have flanges to cover the edge of the glass.

1936- mid 1950s - The "improved cursor" with a metal rim around the glass was introduced.

Mid 1950s-1975 - The glass cursor lenses are replaced with molded plastic ones.
[end]
Notes Text as found 2010 at: http://sliderulemuseum.com/SR_Dates.htm#KE

Here are some excerpts written by Clark McCoy:

Serial Numbers:

Serial numbers started in 1924 beginning with 0 and going through 999999 then rolling over to 0 again. There were three rollovers occurring in 1943-1944, 1954, and 1962. In general the production rate was about 70,000 rules per year until the 1950s. In the 1950s and it was over 100,000 per year. The 1960s had a production rate of about 100,000 per year for several years and tapering off in the 1970s ending at about 700000. In general it is safe to assume a linear production rate between the rollover dates particularly for the common types rules.
Serial numbers can be used to approximate the manufacture date of a given rule however not necessarily the sales date. The common rules were produced in regular batches but the specialty rules did not sell as well and a given batch of rules might stretch over several years. It is not uncommon to find rules in the 1960s in 68 xxxx series packaging but 4000 series model numbers on the rules. The Fuller and Thacher's slide rules had their own serial number systems.


Model Numbers: There were four different number series in the history of the slide rule line.
1881-1883 -The numbers 479-481 were used.
1887-1899 -The numbers 1740-1749 were used. There was little if no logic to these numbers.
1900-1961 -The numbers 4000-4199 were used. There were logical groupings of numbers and dash numbers were used to depict length variations of a given rule type. "N" was used as a prefix many times to denote some change in a given model. The use of the "N" prefix is not always consistent. Removal of the "N" prefix also indicated a variation in the model.
1962-1975 -The numbers were converted to a 68-xxxx number series. The dash number scheme for length variations was abandoned. There are numerous examples of 68 xxxx series numbers on retail boxes and the slide rule inside has the old 4000 series number on it. We are sure that this was in the early 1960s while they were working through old 4000 series stock.
Cursor Types: The cursors used on K&E slide rules evolved over the years. When they changed, all production of all models was switched over.There is a definite timeline to the cursor models.

Before 1906 - Slide rules either had no cursor, a brass chisel type cursor, or a metal framed glass cursor.
1913-1915 - A complex cursor that has been named the "column cursor" was introduced for duplex rules.
1915 - All slide rules were fitted with an all glass cursor. The first issue had metal end blocks.
1916-1933 - The metal cursor cursor blocks on the all glass cursor were replaced with plastic ones.
1933-1935 - The plastic cursor blocks were modified to have flanges to cover the edge of the glass.
1936- mid 1950s - The "improved cursor" with a metal rim around the glass was introduced.
mid 1950s-1975 - The glass cursor lenses are replaced with molded plastic ones.
[end]

---------

http://sliderulemuseum.com/SR_WhosWho.htm (as of 2010)

Edwin J. Chamberlain - Etna, NH. Collector/Author/Arctic Engineer/Conservationist. Fellow of the Oughtred Society and on its Board of Directors. Specializes in collecting "long scale" and "decimal keeping" slide rules and their histories. Ed has written many articles about these slide rule types and welcomes new data concerning them. Also interested in slide rules dating before the early 1900's including early K&E and Lenoir/Tavernier/Gravet slide rules.

Clark McCoy - Roseville, CA. Collector. Membership Secretary and Fellow of the Oughtred Society. Webmaster for the popular McCoy's K&E Catologs website. Retired Engineering manager
Date 2010
Year Range from 2010.0
Year Range to 2010.0
Search Terms K & E
K & E Salisbury Products Division
Keuffel & Esser Co.
Caption Keuffel & Esser (K&E) Slide Rule Dates
Imagefile 073\20100020025.jpg
Classification Manufacturing
Business & Commerce