An F-9 field plotter by Interpretation Systems Incorporated, 24 x 14 x 4, with on/off switch, probe input, a block of nine dial knobs, a balance gauge, dial knobs for calibration and contour selection, and large window with cork backing. Upper and lower portions feature pairs of latches, with the lower set opening back panel to reveal interior wiring. Includes the original Interpretation Systems Incorporated shipping box. In very good to fine condition.
