Importance

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Abstract

A direct reading map plotter for converting grid values to magnetic values and vice versa without having to perform arithmetic calculations. The plotter includes a transparent base having a recess formed therein in which is rotatably supported a transparent disc. A compass rose having its center located at the center of rotation of the disc is imprinted upon the base about the periphery of the recess. A heading line representing magnetic north is also imprinted in the base with the line passing through the center of the rose and being arranged to point at the zero mark on the rose. A second diametrical line representing grid north is imprinted upon the disc so that it is caused to turn therewith. A declination scale is provided on the disc which extends to either side of the grid north line whereby the grid north line can be accurately positioned in relation to the magnetic north line.

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First Claim