Totally recommend this book as others have noted "Carolan- the life and times of an Irish Harper by Donal O'Sullivan"

I don't think it is fair to say that Carolan composed all his own tunes, in the same way that many "classical composers" did not compose their own tunes. Whilst he composed a great number of tunes others must have been adapted from the existing tunes with which he was familiar. He was influenced by baroque music but he was also influenced by existing harp music in ireland. [There are losts of examples of composers adapting folk tunes or Christmas carols or whatever]

In the Guiness store house (the tourist trap tour) in Dublin in the exhibition of marketing and advertising memorabilia is what I would call a clarsach (or a small harp). It is about 3 feet tall. It is reputed to be the Harp used by Denis Hempson who was a slightly later contempory of Carolan and used by him at the Belfast Harp Festival. Carolan is also believed to have played at the festival on a number of occasions.