Coordinate Measuring Device

an instrument for measuring coordinate points (of reference marks, localities, and the like) on topographical maps with rectangular coordinate grids. Such devices are also used for plotting points on maps according to coordinates. Sometimes the coordinate measuring device is a transparent rectangular film (celluloid or other) with a square cutout in the center and scales along the margins, corresponding to the sides of the squares of the coordinate grid on maps with scales of 1:25,000, 1:50,000, or 1:100,000.