In the early 1820s, a consistent island-wide valuation of property in Ireland was initiated by the British parliament as a basis for an effective taxation system. The Valuation involved military engineers, through the Ordnance Survey, mapping and setting administrative boundaries and assessing the productive capacity of all property in the country in a uniform way.
The Ordnance Survey Letters are the surveyors' field notes, commentaries and correspondence to the Ordnance Survey headquarters in Dublin. They were written between 1834 and 1841 and exist for twenty-nine counties, excluding Cork, Antrim, and Tyrone. The Letters' collection is commonly known as O'Donovan's Ordnance Survey Letters, after the historian, John O'Donovan (1806-1861), who led the project of information collection, notation and compilation. The collection provides a unique glimpse into everyday life in many parts of Ireland in the years leading up to the Great Famine. The Letters provide the surveyors' experiences of the places they visited and their accounts of the local history, topography and antiquities of each parish. Also included are their informal reflections on the living conditions and impressions of the local people in the parishes visited.
Access to the letters is provided by the Royal Irish Academy.