Notes: "The K&E 4083 Log Log Duplex Vector slide rule was made from 1939 to 1967, and was an evolution of the earlier 4093, which had the same name. Both slide rules were targeted at engineers in the rapidly evolving field of electrical engineering. Their distinctive features were scales for hyperbolic sines and tangents, and decimally divided trig scales (as opposed to divisions in degrees, minutes, and seconds, which was the norm up to that time). This K&E model N4083-3 appears to be from the early 1950’s, as it still has the “N” prefix to the model number but has the scale arrangement introduced in 1954, when the “N” was dropped."
