What instrument did Young Jefferson play and what was special about the tunes?

Young Jefferson played the bagpipes. The only tune he ever learned to play "sounded Scotch".

Young Jefferson only learnt to play one tune on those bagpipes; but I never heard any complaints about the insufficiency of his repertoire—none whatever. This tune was “The Campbells are Coming, Hooray—Hooray!” so he said, though his father always held that it was “The Blue Bells of Scotland.” Nobody seemed quite sure what it was exactly, but they all agreed that it sounded Scotch.