The thesis will seek to advance the understanding of the multitude of interacting social, economic, political, geographic, as well as technological factors that were to shape the development of optical and electrical communications in Ireland. It will do this by tracing the development of three separate technologies: the optical telegraph of R.L. Edgeworth, the electro-magnetic telegraph, and the telephone. Central to the development of these technologies was Ireland’s nineteenth-century membership of the United Kingdom. The fact that its partner in this union, and nearest neighbour, was an economic powerhouse was to have a significant impact on the development of these technologies in Ireland. It must be noted that science and technology are also strongly influenced by local factors and, as Peter J. Bowler and Nicholas Whyte have highlighted, this was as true for Ireland as anywhere else. Thus, this thesis seeks to understand how the development of optic, and electric, telegraph and telephone networks were shaped by British national interests and the desire for connections with continental Europe and North America. In addition, alongside these national and international interests, the thesis will demonstrate that the development of these networks was also strongly influenced by regional and local factors.