Mind you, it would be foolish to assume that the Irish names given in O'Neill are the "real" names of the tunes. I have spent many a night in the company of musicians and have never heard any of them (including fluent Gaelic speakers) use the Irish name of a tune. And I would strongly suspect that O'Neill himself knew these tunes by their English names and translated them into Irish for his book. There are, of course, some pieces that arre only known by their Irish name- An Coolin and Roisin Dubh, for example.