K'Eogh (Keogh), John (c.1650–c.1725), clergyman and scholar, was born at Cloonclieve (subsequently renamed Rivers), Co. Limerick, into an old Irish family, originally called Mac Eochaidh (Mac Eochodh), which lost its estates during the Cromwellian wars. The family name changed for historical, religious, and other reasons through the centuries. He was the son of Dennis MacKeogh (b. c.1620) of Castletroy, Co. Limerick, who married Mrs Eyres (née Wittington), a clergyman's widow. Reared a protestant since his mother was of that persuasion, he was educated in Dublin before matriculating for TCD (1669); becoming a scholar in 1674, he graduated MA (Dubl.) (1678), but twice failed to gain a fellowship, the college apparently fearing that he might neglect its affairs in the interests of scholarship. Ordained by John Hodson (d. 1686), bishop of Elphin and possibly a relative, who installed him (1678) in the prebend of Termonbarry, K'Eogh settled in Strokestown, Co. Roscommon. He made no attempt to recover the family estates or seek compensation; uninterested in honours or preferment, he ran a school and devoted his life to scholarship.
One of the fourteen founding members of the Dublin Philosophical Society (1683), he was enthusiastic about its aims and corresponded frequently with the secretary during the first year (Molyneux papers, TCD, 888–9). His contributions are of varying value, but are notable in that he used Latin as a means of communication. In March 1684 K'Eogh sent a detailed description of Co. Roscommon to William Molyneux (qv), who replied, praising him as the kind of scientist that the society favoured and holding him in high esteem as a mathematician for his willingness ‘not to take things for granted without full assurance of them’ (Molyneux to Keogh, 22 March 1684; RIA, MS 12/W/22, p. 15).
A copy of K'Eogh's ‘A statistical account of the County Roscommon drawn up for Sir William Petty, superintendent of the Down survey’ (1683) is held in NLI, MS 3649. K'Eogh was again in correspondence with the Society 1707–8, and his letters and memoranda are preserved in ‘The letter book of Samuel Molyneux of TCD 1707–09’ (Southampton Corporation, MSS).
According to his son John, he wrote a number of works, all unpublished, including ‘Scala metaphysica’ (demonstrating mathematically ‘what dependence the several degrees of beings have on God Almighty, from the highest angel to the lowest insect’ (K'Eogh, 143)), a Hebrew lexicon, Latin and Greek grammars, ‘De orthographia’, and ‘A demonstration in Latin verse of the Trinity’, which (again, according to his son John) was approved by Isaac Newton (1642–1727). He died in 1725 in Strokestown. He married (1679) Avis Clopton; they had twenty-one children, of whom only six survived him. His second son, Michael K'Eogh (c.1682–c.1734), was educated at TCD and became a clergyman in Strokestown.
His eldest son, John K'Eogh (c.1681–1754), clergyman and naturalist, was born in Strokestown and educated by his father before matriculating for TCD (1705) and graduating BA (Dubl.) (1711). After ordination and before his incumbency at Mitchelstown, Co. Cork, he served as chaplain to the 4th Baron Kingston (1693-1761) in Mitchelstown, and compiled Botanalogia universalis Hibernica; or general Irish herbal (Cork, 1735). An alphabetical list of plants growing in Ireland, with their names given in English, Latin, and Irish, it described their medicinal properties and was based mainly on the plants grown in Kingston's garden. In the preface K'Eogh maintained that every local tree or plant was potentially serviceable to man as either food or medicine or both, and that if their properties could be discovered, every ailment could be cured or alleviated, a means that would be more effective than the prescriptions of apothecaries. The work is of historical value as evidence of the plants which were cultivated at that time, which include orange and lemon trees grown in what was a very early greenhouse. Botanalogia was republished as An Irish herbal, edited by Michael Scott (1986). K'Eogh also wrote Zoologia medicinalis Hibernica (1739) and A vindication of the antiquities of Ireland, and a defence thereof against all the calumnies and aspersions cast on it by foreigners (1748), which included an etymological treatise on the place and proper names of the Irish people, an appendix on the descent of the principal Milesian families in Ireland, and an account of his own family; he refrained from writing about himself ‘being so well known to the best gentlemen in the kingdom’ (K'Eogh, 148). He died in 1754. He married Elizabeth Jennings, a relative of the duchess of Marlborough; they had one son.