All About Slide Rules Book (PDF)

[Benjer]

Doric is a name K&E applied to many of their plastic slide rules to further distinguish them from the celluloid-on-wood models they had been producing. They called this plastic "Ivorite" and I would say it lies at the better end of the spectrum of plastic slide rules that I have handled.

The number of interest on your slide rule is 68 1555, which is its model number. K&E switched to 68x model numbers around 1962 and used them until production ended in the 70s. Your slide rule may also have a serial number which might provide a more specific date if that interests you.

This model contains a fairly standard set of scales and can be used to perform most computations that slide rules were capable of.