Hydrography

Hydrography, as a branch of physical geography, deals with the waters of the globe in so far as they are available for navigation. The hydrographer determines by means of observations and soundings the outline of coasts and shores, the configuration of river-beds, lake-basins, and the seabottom adjacent to coasts, ascertains the position and extent of shoals and rocks and islands, as well as of beacons and lighthouses, investigates the nature and velocity of currents, the local tidal phenomena, the changes taking place in river-mouths and in harbours, and the alterations effected in coast-lines by the action of the sea. All these details it is his business to embody, as far as may be, in charts and maps which shall be serviceable for the practical mariner. See CHART.