| 摘要 |
A map reading and plotting instrument for use with a scaled map having a declination diagram. The instrument includes a first transparent disc with a scale provided adjacent its periphery and a second transparent disc coaxially aligned with the first disc, the second disc having a cut out portion. A hollow securing element is provided connecting the first and second discs and a center of each of the discs for rotative movement independent of each other. At least one arm is provided in a flat rectangular configuration with a scale provided thereon. The arm is disposed between the first and second discs and secured to the securing element connecting the two discs and the arm for pivotal movement independent of the first and second discs. A sight-slide subassembly is provided pivotably connected to the second disc at a second disc sight-slide pivot location. The sight-slide subassembly includes a sight and slide scale of linear measure extending from a first location to a second location of the subassembly. A sight-slide connection guide arrangement is provided including tracks formed in the subassembly and a sight guide which is movable along the tracks between the first and second location for movement relative to the sight-slide scale, the sight including an opening positionable for accessing the map through the opening.
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