Ordnance Survey Ireland

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The Ordnance Survey Ireland (Irish: Suirbhéireacht Ordanáis Éireann) is an Irish government body which prepares maps for the Republic of Ireland. It was separated from the Ordnnace Survey in 1922, when the Irish Free State was created.

Ireland is mapped using the Irish Grid. The Ordnance Survey of Ireland works closely with the Ordnance Survey of Northern Ireland, the equivalent British government body for Northern Ireland, to ensure consistency. Many maps inevitably cross the border and are perforce drawn with shared data between the two.


Under the Ordnance Survey Ireland Act 2001 [1] the status of the former Ordnance Survey of Ireland was changed from an executive agency of the Department of Finance to a State Agency called Ordnance Survey Ireland, and ceased to be part of the Civil service of the Republic of Ireland. OSi is now an autonomous agency, with a remit to cover its costs of operation from its sales of data and derived material, which has, sometimes raised concerns about the mixing of public responsibilities with commercial imperatives. It employs 320 staff located in Dublin’s Phoenix Park and in six regional offices in Cork, Ennis, Kilkenny, Longford, Sligo and Tuam.[2] OSI had sales in 2010 of € 20.3 million.

The body is governed by a Board appointed by the Minister for Finance.


The most prominent consumer publications of OSi are the "Dublin City and District Street Guide", an atlas of Dublin city, and the "Complete Road Atlas of Ireland" which it publishes in co-operation with the Ordnance Survey of Northern Ireland. The board also publishes (jointly with OSNI) a series of 1:50000 maps of the entire island known as the "Discovery Series"[3] and a series of 1:25000 maps of places of interest (such as the Aran Islands and Killarney national park) and the Geology of Ireland.[4]


Mountjoy House, the headquarters of Ordnance Survey Ireland, Dublin

The Irish Survey was established in 1824, along similar lines to the Ordnance Survey in Great Britain, to provide a highly detailed (1:10560, 6 inches to 1 mile) survey of the whole of the island of Ireland, a key element in the process of equalising local taxation.

From 1825-46, teams of surveyors, led by officers of the Royal Engineers and men from the ranks of the Royal Sappers and Miners, traversed Ireland, creating a unique record of a landscape undergoing rapid transformation. The resulting maps, which many consider beautiful, (primarily at 6″ scale, with greater detail for urban areas, to an extreme extent in Dublin) portrayed the country in a degree of detail never attempted before, and when the survey of the whole country was completed in 1846, it was a world first. Both the maps and surveying were executed to a the high degree of engineering excellence available at the time, using triangulation and with the help of tools developed for the project, most notably the strong "limelight." The concrete triangulation posts built on the summits of many Irish mountains can still be seen to this day.

The Engineer officers in charge of the operation were Lt-Colonel Thomas Colby, a long-serving Director-General of the Ordnance Survey, and Lieutenant Thomas Larcom. They were assisted by George Petrie, who headed the Survey's Topographical Department which employed the likes of John O'Donovan and Eugene O'Curry in scholarly research into placenames. Captain J E Portlock compiled extensive information on agricultural produce and natural history, particularly geology.

This "mapping scheme" provided numerous opportunities for employment to the native Irishmen, both as skilled or semi-skilled fieldwork labourers and as clerks in the subsidiary Memoir project that was designed both to illustrate and complement the maps by providing hard data on the social and industrial worth of the country.

The total cost of the Irish Survey was £860,000.

The original survey was later revisited and revised maps issued on a number of occasions. All of these historical maps (at least up to 1922) are in the public domain and while the originals can be hard to find, they can be freely reproduced.

The British Ordnance Survey ceased to map Ireland just before Partition in 1922. The new Ordnance Survey of Northern Ireland (OSNI) officially came into existence on 1 January 1922, while the new Ordnance Survey of Ireland (OSi) came into being slightly later, on 1 April 1922.

OSI was initially part of the army under the Department of Defence. All staff employed were military until the 1970s when the first civilian employees were recruited.[5]

In more recent times, the Ordnance Survey of Ireland replaced traditional ground surveying with mapping based primarily on aerial photography. It has also worked with An Post (the Post Office) to gather and structure geographic data.

See also

Outside links


  • Andrews, J.H., A Paper landscape: the Ordnance Survey in nineteenth-century Ireland (Oxford, 1975).
  • McWilliams, P.S., "The Ordnance Survey Memoir of Ireland: Origins, Progress and Decline" (PhD thesis, Queen's University Belfast, 2004).
  • Report on Ordnance Memoir (1843), HC 1844 (527) xxx, 259-385.
  • An Illustrated Record of the Ordnance Survey in Ireland (The O.S.I., Dublin, and the O.S.N.I., Belfast, 1991).