Ordnance Survey

The Ordnance Surveys of Ireland (OSI) and Northern Ireland (OSNI) are the official state mapping agencies in Ireland. The Ordnance Survey developed in the late 1820s out of an earlier wartime British mapping initiative by the Board of Ordnance in England. The need to reform Ireland's local taxation system called for a comprehensive valuation of land and buildings, and the Royal Engineers Artillery formed the core of the new Ordnance Survey, which was based in the Phoenix Park in Dublin. Its greatest pioneering achievement was the mapping of Ireland at a scale of six inches to the mile between 1833 and 1846. This project recorded all town-land units, field boundaries, and acreages, buildings in urban and rural areas, place-names, and data on heights above sea level; it has become an invaluable topographic record of the Irish landscape on the eve of the Great Famine. The Ordnance Survey Memoirs were intended by the director Thomas Colby as a comprehensive textual profile of each civil parish to accompany the maps, but officials succeeded in publishing only one parish memoir. The material on the remaining parishes for much of Ulster was published in the 1990s. The Ordnance Survey Letters of John O'Donovan, an Irish language scholar who was almost single-handedly responsible for standardizing the thousands of place-names on the maps, will be published in the early twenty-first century.

The 6-inch maps were published in county volumes, which were revised at various times throughout nineteenth century. Maps at 1:2500 ("twenty-five inches to the mile") were undertaken from 1864 until the early twentieth century. These maps provided detail on acreages of fields, which was of great use for the implementation of the Irish Land Acts and the transfer of farms from landlords to tenants, as well as for the reform of rundale (field system) plots and settlements in the west of the country by the Congested Districts Board and the Land Commission. The Ordnance Survey also produced large-scale town plans from the 1840s, some at 1:1056, or 5 feet to 1 mile; others at 10 feet to 1 mile; and still others at more economical scales. The 1-inch maps were designed as a popular scale from the 1850s, and the half-inch map was produced in the early twentieth century.

The OSI today produces urban, rural, and leisure mapping for a range of different scales, in digital and paper format. The 1:50,000 Discovery series is the most popular product in the early twenty-first century. The Ordnance Survey's digital data are used under license for many computer-based applications, such as Computer-Aided Design (CAD) and Geographic Information Systems (GIS).

SEE ALSO Landscape and Settlement; O'Donovan, John

Bibliography

Andrews, John H. A Paper Landscape: The Ordnance Survey in Nineteenth-Century Ireland. 1975.

Day, Angelique, and Patrick McWilliams, eds. Ordnance Survey Memoirs of Ireland. 40 vols. 1992.

Patrick J. Duffy