Some further notes, though so far no more tunes:The Celtic Cross was written by Thomas D'Arcy McGee (1821-1868). His poem appeared in Lyra Celtica (1896, revised 1924), with the following note by William Sharp (alias Fiona MacLeod):
"This distinguished Irishman is to be accounted only an adopted American. He emigrated to the States in 1842, edited The Boston Pilot, and in 1857 went to Montreal and entered the Canadian Parliament. It was when returning from a night-session that he was assassinated in Ottawa by Fenian malcontents."
There was a discussion about him here some months ago: Thomas D'Arcy McGee; I haven't found out what melody the poem was set to.
Various McFaddens were the heroes of a series of comic songs, mainly late 19th century "Stage Irish". The Levy Collection has McFadden's Trotting Mare, Since McFadden Bought the Cornet, McFadden's Debut and Learning McFadden To Waltz; but not, unfortunately, our example.
There is a copy of The lads who live in Ireland, or Where the apple praties grow at America Singing: Nineteenth-Century Song Sheets. It was printed by H. De Marsan of New York, and is undated. "Composed and Sung by JAS SEYMOUR, at Niblo's, in the "Duke's Motto." The music to be had of H. B. Dodworth, 6 Astor Place."
Further enquiries reveal that The Duke's Motto was a musical melodrama written by the Irish actor/playwright John Brougham, based very closely on a French original by Paul Feval. The music was written by the English composer William Henry Montgomery. The play was first produced in 1863 at the Lyceum in London, and subsequently at Niblo's Garden and Daly's Fifth Avenue Theater (both presumably New York). Whether the actor Seymour actually had anything to do with the music or words of the song I have no idea; nor have I found the tune itself.