Notes: "This flight computer was issued by American Airlines during or shortly after WW2. The front is an early form of the circular slide rule found on E-6B flight computers. The rear is a strange and unique form of wind correction computer. It is not the same as either the E-6B or the Jeppesen CR series of computers. The slide rule layout on the front is copyright 1933 by Philip Dalton, so about 8 years before he invented the E-6B. The wind side was patented in 1933, and revised in 1944"