I am intrigued by Donald MacDonald’s arrangements of ceòl mór or pibroch, because on his title page he indicates that he is not setting out the tunes in “pipers tablature”, that cryptic system that looks confusingly similar to staff notation; instead, he describes his work:
A / collection / of the / Ancient Martial / Music of Caledonia / called / Piobaireachd / as performed on the / Great Highland Bagpipe / Now also adapted to the / Piano Forte, violin and violoncello…
By setting the music on two staves, treble and bass, he intends that the purchasers of his book, price one guinea (£1 1s, or a few hundred pounds in today’s money) to play this music not on the pipes (what wealthy, musically literate book-buyer in 1820 owned or played pipes?) but on the piano; if they had musical guests at their Edinburgh townhouse they may well also try it as violin and cello duets.
Donald writes a single bass line very simply in the bass clef, which looks to me quite old-fashioned for 1820; I think by that date many music arrangers were writing chordal and thicker textures in the bass. On the other hand the modal, drone-based nature of the music may have discouraged anything more complex.
He writes the melody in a more nuanced way, setting the tune in large notes with their stems all pointing down, and using little notes with the stems up to indicate the characteristic bagpipe grace-notes. I imagine he expected piano and fiddle players to ignore these in performance, but to appreciate them as exotic talking-points read in connection with the “instructions” at the beginning of the book.
How did he decide which notes to make big, and which small? This is the vexed question of all early pibroch scholarship, since there seems to have been a strong movement through the 19th and 20th century to shift the musical emphasis in a big way, with melody notes becoming swallowed up into bundles of gracenotes, and rogue grace notes being held so long that they speak as stressed melody notes.
My opinion is that he wrote the big notes so that when played normally on the fiddle or piano, the melody sounded as he imagined in his head that it should, based on his knowledge of the expected traditional expression of this tune on the pipes (and perhaps also on the fiddle, seeing as the fiddle pibroch tradition may have still been reasonably strong at this time)