Geography. angular distance east or west on the earth's surface, measured by the angle contained between the meridian of a particular place and some prime meridian, as that of Greenwich, England, and expressed either in degrees or by some corresponding difference in time.
Decimal time and longitude would then correlate directly without the need for logarithmic conversion tables.
Section of equator, two lines of longitude one on either side, one pole where the lines of longitude meet.
The second method has been around since the invention of the marine chronometer to determine longitude.
Comparatively few of those who habitually make use of longitude are familiar with its history.
British Dictionary definitions for longitude
distance in degrees east or west of the prime meridian at 0° measured by the angle between the plane of the prime meridian and that of the meridian through the point in question, or by the corresponding time difference See latitude (sense 1)
A measure of relative position east or west on the Earth's surface, given in degrees from a certain meridian, usually the prime meridian at Greenwich, England, which has a longitude of 0°. The distance of a degree of longitude is about 69 statute miles or 60 nautical miles (111 km) at the equator, decreasing to zero at the poles. Longitude and latitude are the coordinates used to identify any point on the Earth's surface. Compare latitude.