AN INSTRUMENT WITH A GRADUATED ARC OF 60 DEGREES AND A SIGHTING MECHANISM, USED FOR MEASURING THE ANGULAR DISTANCES BETWEEN OBJECTS AND ESPECIALLY FOR TAKING ALTITUDES IN NAVIGATION.
THE ANGULAR DISTANCE OF A PLACE EAST OR WEST OF THE MERIDIAN AT GREENWICH, ENGLAND, OR WEST OF THE STANDARD MERIDIAN OF A CELESTIAL OBJECT, USUALLY EXPRESSED IN DEGREES AND MINUTES.
THE ANGULAR OF A PLACE NORTH OR SOUTH OF THE EARTH'S EQUATOR, OR OF A CELESTIAL OBJECT NORTH OR SOUTH OF THE CELESTIAL EQUATOR, USUALLY EXPRESSED IN DEGREES OR MINUTES.
THE STUDY OF THE PHYSICAL FEATURES OF THE EARTH AND ITS ATMOSPHERE, AND OF HUMAN ACTIVITY AS IT EFFECTS AND IS AFFECTED BY THESE, INCLUDING THE DISTRIBUTION OF POPULATIONS AND RESOURCES, LAND USE, AND INDUSTRIES.