Ordnance Survey Ireland - History

History

The Irish Survey was established in 1824 along similar lines to the Ordnance Survey in Great Britain, to provide a highly detailed survey of the whole of the island of Ireland (1:10560, 6 inches to 1 mile), 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 (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 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 Irish people as skilled or semi-skilled fieldwork labourers, and as clerks in the subsidiary Memoir project that was designed to illustrate and complement the maps by providing data on the social and productive 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 Irish army under the Department of Defence. All staff employed were military until the 1970s when the first civilian employees were recruited.

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 the postal service, An Post, to gather and structure geographic data.