Eluned (and everybody) -
Ossian Publications in Cork are issuing (if they haven't already) a compilation of ALL the O'Neill volumes. Info from firstname.lastname@example.org
O'Neill was a Cork man who emigrated to America (after having travelled widely) in the early 20th century, where he rose in the ranks of the police force and made valuable collections of Irish traditional music which are still used today. Ossian (no, I don't work for them!) also publishes an interesting account of his life which includes a lot of photos, written by Nicholas Carolan who runs the traditional music archive in Dublin.