Details and Image
Area of Use
Circular and Spiral Slide Rules
American Hydromath / Coasting Computer & Cross Drift Detector (1)
American Hydromath Co.
Ø 15.2 cm
Made as a set of two simplex discs for US Maritime Commission - see sibling Pitch-Speed-RPM model. Could be seen as a ship captain?s equivalent of a pilot?s E6-B flight computer.