Rory Dall O'Cahan/O'Caghan died about two hundred years before 1855, and he is not known to have had anything to do with the tune. See the real history at www.standinstones.com, or see the oldest version of the tune, and its song, "The Young Man's Dream" on my website (Scarce Songs 1 file). You can click on Michael Robinson's "Danny Boy" history at standingstones from the bottom of my homepage. www.erols.com/olsonwThe 'Londonderry Air' version of tune as first published by G. Petrie in 1855 is also on my website, as well as Ann Geddes Gilchrist's reconstructed version.