Keuffel and Esser produced slide rules from 1881 right through to 1975. Prior to 1906 the slide rules either had no cursor, a brass chisel type cursor, or a metal framed cursor. This cursor on this slide rule is made of glass held by plastic cursor blocks and appears to be from ~1928. [^The estimate is made on the basis that "serial numbers started in 1924 beginning with 0 and going through 999999 then rolling over to 0 again and in general the production rate was about 70,000 rules per year until the 1950s.
 [[http://www.mccoys-kecatalogs.com/Dating.htm|Clark McCoy, Mccoys-kecatalogs.com "Dating K&E Slide Rules"]].  See also [[http://www.mccoys-kecatalogs.com/KECollection/4088/ke4088-3_s1_2.htm|K&E 4088-3 ---- 1913-1921 Scale Set]] (viewed 12 July 2012)^]

!!1913-21: K & E 4088-3 1913-1921 s/n 348119 Slide Rule

Keuffel and Esser produced slide rules from 1881 right through to 1975. However, prior to 1906 the slide rules either had no cursor, a brass chisel type cursor, or a metal framed cursor. This cursor on this slide rule is made of glass held by metal cursor blocks and appears to be from 1913-21. [^[[http://www.mccoys-kecatalogs.com/Dating.htm|Clark McCoy, Mccoys-kecatalogs.com "Dating K&E Slide Rules"]]  and [[http://www.mccoys-kecatalogs.com/KECollection/4088/ke4088-3_s1_2.htm|K&E 4088-3 ---- 1913-1921 Scale Set]] (viewed 12 July 2012)^]

!!! From the K&E catalogue of 1906, p. 325[^[[http://www.mccoys-kecatalogs.com/KECatalogs/1906/1906kecatp324.htm|Clark McCoy Mccoys-kecatalogs.com "Slide Rule Section of the 1906 K&E General Catalog"]] (viewed 12 July 2012)^]:

!!1908: K & E 4088-3 1913-1921 s/n 348119 Slide Rule

!!1908: K & E 4088-3 22 Dec 1908 s/n 348119 Slide Rule

Keuffel and Esser produced slide rules from 1881 right through to 1975. However, prior to 1906 the slide rules either had no cursor, a brass chisel type cursor, or the metal framed cursor possessed by this slide rule.  An all glass cursor was introduced in 1915. [^[[http://www.mccoys-kecatalogs.com/Dating.htm|Clark McCoy, Mccoys-kecatalogs.com "Dating K&E Slide Rules"]] (viewed 12 July 2012)^]

Keuffel and Esser produced slide rules from 1881 right through to 1975. However, prior to 1906 the slide rules either had no cursor, a brass chisel type cursor, or the metal framed cursor possessed by this slide rule.  An all glass cursor was introduced in 1915. [^[[http://www.mccoys-kecatalogs.com/Dating.htm|Mccoys-kecatalogs.com "Dating K&E Slide Rules"]] (viewed 12 July 2012)^]

!!! From the K&E catalogue of 1906, p. 325[^[[http://www.mccoys-kecatalogs.com/KECatalogs/1906/1906kecatp324.htm|Mccoys-kecatalogs.com "Slide Rule Section of the 1906 K&E General Catalog"]] (viewed 12 July 2012)^]:

Keuffel and Esser produced slide rules from 1881 right through to 1975. However, prior to 1906 the slide rules either had no cursor, a brass chisel type cursor, or the metal framed cursor possessed by this slide rule.  An all glass cursor was introduced in 1915. [^http://www.mccoys-kecatalogs.com/Dating.htm|Mccoys-kecatalogs.com "Dating K&E Slide Rules"]] (viewed 12 July 2012^]

!!! From the K&E catalogue of 1906, p. 325[^[[http://www.mccoys-kecatalogs.com/KECatalogs/1906/1906kecatp324.htm|Mccoys-kecatalogs.com "Slide Rule Section of the 1906 K&E General Catalog"]] (viewed 12 July 2012^]:

!!! From the K&E catalogue of 1906, p. 325[^[[http://www.mccoys-kecatalogs.com/KECatalogs/1906/1906kecatp324.htm|Mccoys-kecatalogs.com]] (viewed 12 July 2012^]:

!!! From the K&E catalogue of 1906, p. 325:

20-INCH RULES

(Case and directions are missing).

Picture and description to be added

1908: K & E 4088-3 22 Dec 1908 s/n 348119 Slide Rule