Antique, 4081-3, Keuffel & Esser Slide Rule Engineers. Rule has a leather storage case included. K-E backstamp.

Antique, 4081-3, Keuffel & Esser Slide Rule Engineers. Rule has a leather storage case included. K-E backstamp.

USA 1947

Size : 31.75 cm L x 5 cm W

The 4081-3 family of slide rules are duplex type of slide rules. The 4080-3 and 4081-3 were constructed on a mahogany frame with celluloid laminated to the surface except for a few all plastic versions. The markings are engine divided on the mahogany framed rules. These rules are identical except for the scale graduations of the trig scales. The 4080-3 is divided in degrees and minutes where as the 4081-3 is divided in degrees and decimal degrees on its trig scales. Of the catalogs available the first release was shown in the 1937 catalog and price list.

This is the second series of slide rules called "Log Log Duplex Trig" (4080-3) and "Log Log Duplex Decitrig" (4081-3). This group was evolved from the 4091-3 family in 1937 and the earlier 4092-3family of slide rules. The 4081-3 family of slide rules became the main stay for the K&E line of slide rules in the 1940s, 50s, and 60s.

The construction of the 4081-3 family evolved during the life of the family group. From 1937 through 1947 the laminate covered the entire surface of the rules except for the ends and all printing was on the front and rear surfaces