Dictionary of National Biography, 1885-1900/O'Brien, John
O'BRIEN, JOHN (d. 1767), Irish catholic prelate, was vicar-general of the united dioceses of Cork, Cloyne, and Ross. In audience of 10 Dec. 1747 Pope Benedict XIV approved the separation of Cork and Cloyne, which had been held in union since 1429, and the appointment of O'Brien to the bishopric of Cloyne and Ross. His brief was dated 10 Jan. 1747–8. He died, according to Brady, in 1767, when he was succeeded in his see by Matthew MacKenna (Episcopal Succession, ii. 99). Martin states, however, that O'Brien was bishop of Cloyne and Ross from 1748 to 1775.
To him is generally attributed, though on somewhat doubtful authority, the authorship of ‘Focalóir Gaoidhilge-Sax-Bhéarla, or an Irish-English Dictionary. Whereof the Irish part hath been compiled not only from various Irish vocabularies, particularly that of Mr. Edward Lhuyd, but also from a great variety of the best Irish manuscripts now extant, especially those that have been composed from the ninth and tenth centuries down to the sixteenth, besides those of the lives of St. Patrick and St. Brigit, written in the sixth and seventh centuries’ (anon.); Paris, 1768, 4to; and again Dublin, 1832, 8vo, edited by Robert Daly, with the assistance of Michael McGinty. In the library of Trinity College, Dublin, there is a copy of the first edition, with manuscript notes by Peter O'Connell; and another copy, with marginal notes chiefly in the handwriting of Maurice O'Gorman and Charles Vallancey, is preserved in the British Museum (Egerton MS. 87). The ‘Dictionary’ is chiefly compiled from the vocabularies of Michael O'Clery [q. v.], Richard Plunkett [q. v.], and Edmund Lhuyd [q. v.], but wants thousands of words still existing in the written and living language. The preface to the work is a learned discourse on the antiquity of the Iberno-Celtic language and its affinity to other tongues, and the remarks which precede each letter of the alphabet are valuable. Much curious genealogical and historical information is scattered through the work.
The bishop edited ‘Monita Pastoralia et Statuta Ecclesiastica, pro unitis Diœcesibus Cloynensi et Rossensi. In quibus etc. Lecta, acceptata, et promulgata in Conventibus Cleri Sæcularis et Regularis utriusque Diœcesis, habitis Anno Domini 1755,’ sine loco, 1756, 16mo, pp. 96 (cf. Martin, Privately Printed Books, 2nd ed. p. 565).
He also wrote ‘A Critico-Historical Dissertation concerning the Antient Irish Laws, or National Customs, called Gavel-Kind, and Thanistry, or Senior Government,’ 2 parts, Dublin, 1774–5, 8vo, forming numbers 3 and 4 of Vallancey's ‘Collectanea de Rebus Hibernicis.’ O'Brien's dissertation was published by Vallancey as if he were himself the author of it (cf. O'Donovan, Irish Grammar, Introd. p. lviii n).
[O'Curry's Cat. of Irish MSS. in Brit. Mus. p. 73; O'Reilly's Irish Writers, p. 232; James Scurry's Review of Irish Grammars and Dictionaries, p. 62, in vol. xv. of Transactions of Royal Irish Acad.; Cat. of Library of Trinity College, Dublin; Vallancey's Grammar of the Iberno-Celtic or Irish Language, 1773, p. 3.]