CHART

A hydrographic map for the use of navigators, being a projection of some part of a coast on a plane surface. Charts as well as ordinary maps may be constructed on any of the principles by which a spherical surface is represented on a plane; but they are generally laid down according to Mercat or's projection, in which the meridians, and consequently also the parallels Of latitude, are represented by parallel straight lines, the degrees of longitude on all the parallels being equal to those of the equator, and the degrees of latitude being Increased from the equator towards the pole, so as to bear always the same ratio to the degrees.of longitude which they do on the sphere itself. See Map and Projection. [s. 228]