the art of measuring and describing the sea, rivers, canals, lakes, &c.—With regard to the sea, it gives an account of its tides, counter-tides, foundings, bays, gulfs, creeks, &c.; as also of the rocks, shelves, sands, shallows, promontories, harbours; the distance and bearing of one port from another; with every thing that is remarkable, whether out at sea or on the coast.