K&E 4092-3 Family of Slide Rules
An error has been noted on all of the 409x-3 series rules. The LL0 scale has an "e" at the beginning and end of the scale. It should be "e to the -1". This error was corrected by K&E between serial numbers 455535 and 460179. This correction appears to be coincident with the introduction of the New Improved Cursor. This serial number dating places this change at probably early 1935.
Scale set #1 (1922-1925)
DF [ CF CIF CI C ] D L
LL0 A [ B S T C ] LL3 LL2 LL1
4092-3 --- 10" Without laminated edges and has production numbers on the end. All glass cursor. Serial # 8041
4092-3 --- 10" Laminated edges. All glass cursor. Serial # 13495
4092-5 --- 20" Laminated edges. All glass cursor. Serial # 32088
Scale set #2 (1925-1937)
K DF [ CF CIF CI C ] D L
LL0 A [ B S T C ] LL3 LL2 LL1
4092-3 --- 10" Laminated edges. All glass cursor. Serial # 261497
4092-3 --- 10" Laminated edges. All glass cursor with corner ridges. Serial # 396126
4092-3 --- 10" Laminated edges. Improved cursor. Serial # 523665
The N4092-3 designation was started in 1925 with the scale change at that time. A rule with that designation has not been seen however some of the boxes were marked such.
N4092-3 - 10" Mahogany with laminated edges.