Exciting news! Ross Anderson of Cambridge University, together with Roderick Cannon, has scanned a full copy of a heretofore unpublished Donald MacDonald manuscript. MacDonald published the first collection of piobaireachd in 1820 and was working on a second collection. This is the draft of that collection. Anderson and Cannon have generously made the manuscript public and here it is.
I have peeked at a few of the pages, but it is going to take a while to look at the whole thing. There are 282 pages! From what I have seen, though, the quality of the images is good and the notation is also very clear. It would not be difficult at all to play from this manuscript. Thank you, gentlemen!