http://meta-studies.net/pmwiki/uploads/KE1908.jpg

http://meta-studies.net/pmwiki/uploads/K&E1908.jpg

~1928: K & E 4088–3 s/n 348119 Slide Rule

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. ¹

¹ 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.” Clark McCoy, Mccoys-kecatalogs.com “Dating K&E Slide Rules”. See also K&E 4088-3 —— 1913-1921 Scale Set (viewed 12 July 2012) (↑)