Francis Collinson 
The Traditional and National Music of Scotland [PDF ebook] 

Originally published in 1966, this was the first book on this subject to be published for over a hundred years. It covers all facets including little-known types of Gaelic song, the bagpipes and their music, including the esoteric subject of pibroch, the Ceol Mor or ‘Great Music’ of the pipes. It gives a comprehensive review of the fiddle composers and their music, and of the Clarsach and its revival, with an example of all-but-extinct Scottish harp music. A chapter is devoted to the music of Orkney and Shetland and the book contains over 100 examples of music many of which were from the author’s own collection and published here for the first time.