I can't give you chapter and verse, Wolfgang, that's just the info I've collected in my Scottish Song Index. I'm glad you reminded me about Der Wasserfall, which I have in a little book from Salzburg, "Fein sein, beinander bleiben", ed. by Cesar Bresgen (1947), which has a different (second) verse to the one in the text in the link above. I'll send it to you by e-mail if you like. Anyway, tho I can't access it right now, my guess is that the roots of the Rossini tune are dealt with in a book by a chap called Fuld, title something like "The Book of World-Famous melodies", or such--he tries to find the first published version of many tunes, from classics to pops, including of course a few folk-tunes. Good hunting! Murray