The John O'Hart (1824 – 1902) Shelf Irish genealogis)

 He was born in Crossmolina, Co. Mayo, Ireland. A committedRoman Catholic, O'Hart originally planned to become Catholic priest but instead spent 2 years as a police officer. He was an Associate in Arts at the Queen's University of Belfast. He worked at the Commissioners of National Education during the years of the Great Irish Famine. He worked as a genealogist and took an interest in Irish history. He was an Irish nationalist. He died in 1902 in Clontarf nearDublin, at the age of 78.

O'Hart's 800-page The Irish and Anglo-Irish landed gentry(Dublin 1884) was reprinted in 1969, with an introduction byEdward MacLysaght, the first Chief Herald of Ireland. Another work, Irish pedigrees; or, The origin and stem of the Irish nation, first published in 1876, has come out in several subsequent editions.

To complete his genealogies he used the writings of Cú Choigcríche Ó Cléirigh, Duald Mac Firbis and O'Farrell, along with the Annals of the Four Masters, for the medieval pedigrees. He used the works of Bernard Burke, John Collins and others to extend his genealogies past the 17th century.

Stem of the Irish nation

In his Irish Pedigrees, O'Hart presents the legendary origins of the Irish people, from the Biblical Adam and Eve through the kings of ancient Ireland. Irish tradition holds that every Irish person is descended from the king Milesius who emigrated from Spain in approximately 1700 BC, according to the Annals of the Four Masters. O'Hart started each of his genealogies with Adam recording Milesius as his 36th descendant.

Ref. https://en.wikipedia.org/wiki/John_O%27Hart

Irish pedigrees; or, The origin and stem of the Irish nation (1892), by John O'Hart, is available in 2 volumes free on the Internet Archive.

Irish pedigrees; or, The origin and stem of the Irish nation (1892), by John O'Hart, - Volume: 1

archive.org/details/irishpedigreesor_01ohar

Irish pedigrees; or, The origin and stem of the Irish nation (1892), by John O'Hart, - Volume: 2

archive.org/details/irishpedigreesor02ohar

Another book by John O'Hart is also available free on the Internet Archive.

The Irish landed gentry when Cromwell came to Ireland (1887), by John O'Hart;

archive.org/details/irishlandedgentr00ohar