• On the Ogham Monuments of the Gaedhal [Gael] (1869); and Do., as George M. Atkinson, ed., The Ogam inscribed monuments of the Gaedhil in the British Islands: With a Dissertation on the Ogam Character (London: G. Bell & Sons 1879), xvi, 425pp., front. port., pl., fold. map.
• The Ecclesiastical Architecture of Ireland to the Close of the 12th century: Accompanied by Interesting Historical and Antiquarian Notices of Numerous Ancient Remains of that Period (Dublin: W. B. Kelly; London: : Simpkin, Marshall, & Co. 1875), xii, 174pp., ill. [54 lvs. of pls.; plans].
• with J. Romilly Allen, The Ogham Inscribed Stones of Wales (1870), and Do., ed. John Sharkey (Felinfach: Llanerch 1992), 100pp.
• Notices, Historical and Architectural, of the Round Tower of Brechin ... From the Proceedings of the Antiquarian Society of Scotland [... &c.] (1862).

See also our Papers Read before the Royal Irish Academy: “On an Ogham-inscribed monument in Glen Fais, County Kerry (1868); “On the Seskinan Ogham inscriptions, county of Waterford” (1869); “On an Ogham-inscribed Pillar-stone at Monataggart, Co. Cork”; “On Two Ogham-inscribed stones from Tinahally, Co. Kerry”; “On an Ogham-inscribed Stone from Mount Music, Co. Cork; On an Ogham-inscribed Pillar-stone at Ballycrovane, Co. Cork” (1874).