This article examines the role that Ireland and Irish people played in the geographical construction of British colonial rule in. India during the nineteenth century. It argues that as ail important sub-imperial centre, Ireland not only supplied the empire with key personnel, but also functioned as an important reference point for scientific practice, new legislation, and systems of government. Occupying integral roles within the information systems of the colonial state, Irish people provided much of the intellectual capital around which British ride in India was constructed. These individuals were part, of nineteenth-century Irish professional personnel networks that viewed the empire as a legitimate sphere for work and a all arena in which they could prosper. Through involvement and deployment of expertise in areas such as surveying and geological research in. India, Irishmen and Irish institutions were able to act decisively, in the development of colonial knowledge. The relationships mapped in this article centre the Irish within the imperial web of connections and global exchange of ideas, technologies, and practices during the long nineteenth century, thereby making a contribution towards uncovering Ireland's multi-directional involvement in the British empire and reassessing the challenges that thin presents to existing British, Irish, and imperial historiography.