SNIPPET: Established under the Board of Ordnance in 1791, the Ordnance Survey was given the task of mapping Britain to new levels of accuracy in anticipation of a feared invasion from France. However, it was civil rather than military needs that brought the survey to Ireland in 1824. Inequities in the local taxation system pointed to the need for an official map of the names, boundaries, and acreage of the 60,000 or so townlands as a prelude to the revaluation of rateable property. The average size of a townland, less than 300 acres, necessitated the adoption of the unprecedented scale of six inches to one mile for what was officially called 'The Townland Survey of Ireland.' The larger scale entailed refined methods for the detailed survey, and for a brief period Dublin was at the cutting edge of cartographic innovation. At the height of the project 2,000 staff were employed, including men of the calibre of Thomas DRUMMOND, John O'DONOVAN, Eugene O'CURRY and George PETRIE, supervised by officers of the Royal Engineers and Royal Artillery under director Col. Thomas COLBY in London and Thomas LARCOM in local charge at Phoenix Park. The survey was carried out county by county between 1825 and 1841, starting in Derry and completed with the maps of Kerry published in 1846. Townland boundaries were determined in advance by a separate department under Richard GRIFFITH, who also conducted the subsequent valuation. Additional information was collected on antiquities, place names, geology, and industry, only some of which ever appeared on the final maps. Completed on the eve of the Great Famine, the 1,900 or so maps show the Irish landscape as it approached its population climax, detailing every road and house, field and settlement, in a finely engraved topographical portrait that is austerely beautiful. On completion the focus of the survey shifted back to Britain, but sufficient staff remained in Ireland to insert field boundaries omitted from the maps of the first eight counties. Their value to government, local government, and landowners ensured that the maps continued to be revised and their range expanded to included detailed town plans as well as small-scale maps aimed at the growing tourist and recreation market. After 1921 the survey became wholly independent and the Ordnance Survey of Northern Ireland was established in Belfast. -- Paul Ferguson, Map Librarian, Trinity College Library, Dublin. More info: Andrews, J. H., "A Paper Landscape: The Ordnance Survey in Nineteenth-Century Ireland" (1975) and "History in the Ordnance Map: An Introduction for Irish Readers" (2nd edn., 1993).