A complete epitome of practical navigation, containing all necessary instruction for keeping a ship's reckoning at sea : with the most approved methods of ascertaining the latitude, by meridian, single, or double altitudes, and the longitude, by chronometers, or lunar observations ; including a journal of a voyage from London to Madeira ; and every other requisite to form the complete navigator ; the whole being rendered perfectly easy, and illustrated by several engravings : to which is added a correct and extensive set of tables, preceded by a copious explanation of each table /