The arc or portion of the equator intersected between
   the meridian of a given place and the meridian of some other place from
   which longitude is reckoned, as from Greenwich, England, or sometimes
   from the capital of a country, as from Washington or Paris. The
   longitude of a place is expressed either in degrees or in time; as,
   that of New York is 74¡ or 4 h. 56 min. west of Greenwich.