Ordnance Survey (OS) is the official mapping organization of the United Kingdom. Founded in 1791 under the Board of Ordnance of the British Army, it is now a civilian organization. Its activities include geodetic, topographic, and other surveying and the preparation and publication of maps. Geodetic surveys make adjustments for Earth’s curvature. Topographic surveys include the measurement of elevations and depressions as well as horizontal distances. The main offices of the OS are at Southampton.
The OS offers a wide range of published maps. The wide range of smaller-scale maps derived from these large-scale maps include the all-purpose 1:50,000-scale Landranger maps.
The state mapping authority in Ireland is the Ordnance Survey, based in Dublin. It makes maps and engages in research on place names and in archaeology.
