In old Scottish and Irish music books and manuscripts, you can find tunes which are attributed “by Rory Dall”. In the past, there has been uncertainty or confusion over which Rory Dall these tunes belong to. Some earlier writers even suggest that there was only one person called Rory Dall.
However, if you set down all the tunes, and compare different sources and settings of each, which have different attributions, and different dates of their first appearance; and if you compare the styles and types of composition, then it is clear that all of the instrumental tunes belong to the Irish Rory Dall.
A couple of tunes with Scottish provenance, which have traditionally been assumed to belong to the Scottish Rory Dall (e.g. Cumha Peathar Ruaidhri, ‘Rory Dall’s Sister’s Lament’) can be found in the Straloch lute book written down c.1627, before Rory Dall Morison was born. Such tunes must belong to Ó Catháin.
I have made a chart detailing all of the music attributed to both Rory Dalls. Click here for the complete tune-list index (PDF) (updated October 2014)