Plane CHART, is a representation of some part of the superficies of the terraqueous globe, in which the meridians are supposed parallel to each other, the parallels of latitude at equal distances, and consequently the degrees of latitude and longitude everywhere equal to each other. See PLANE Chart.
Mercator's CHART, is that where the meridians are straight lines, parallel to each other, and equidistant; the parallels are also straight lines, and parallel to each other; but the distance between them increases from the equinoctial towards either pole, in the ratio of the secant of the latitude to the radius. See NAVIGATION.