Notes: "The K&E 4070-3 slide rule was first introduced in 1939, replacing the 4088-3. It inherited the “Polyphase Duplex” name, but added “Trig” or “Decitrig” on the end of it, depending on whether the trig scales were divided in degrees and minutes of arc, or in decimal degrees. In 1955 the ST scale was replaced with an SRT scale, dating this one to earlier than 1955. The upper and lower edges of the stators have an inlaid strip of celluloid, rather than being completely covered in celluloid, a very attractive feature that K&E started using in 1952. The serial number, 834549, indicates it was made, roughly, in 1953 or 1954. The 4070-3 last appeared in the K&E catalog in 1967. "
