The Piobaireachd Society, formed in 1903, encourages and studies the playing of piobaireachd, the classical music of the Highland bagpipe. It has amassed a sizable collection of piobaireachd manuscripts and makes them available as pdf documents on their website. Here’s just a few of the more notable and interesting settings avaialable:
The Hannay-McAuslin Manuscript
The Kintarbert Manuscript of Angus MacKay
The Seaforth Manuscript of Angus MacKay