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Reading " "The dialect of the southern counties of Scotland" (1873ish), by James Augustus Henry Murray of OED fame, having found a nice scan of it at
https://babel.hathitrust.org/cgi/pt?id=hvd.32044004779468&seq=27
after reading about it in M's copy of "The Professor and the Madman", of which Murray is the titular Professor.
I may well not get past the extensive Historical Introduction, but that is fascinating in itself. The story of how the name "Scotland" and related terms came to gradually change its denotation over the years is a small gem.
"It is in this latter or geographical sense that the dialect which forms the subject of this paper is called Scottish. Ethnologically speaking, the Lowland Scotch dialects are Scottish only in the sense in which the brogue spoken by the descendants of Strongbow's followers, or of the Cromwellian settlers, is Irish; or in which the Yankee dialect of the descendants of the New England Puritans is American - in other words, they are not Scottish at all. They are forms of the Angle, or English, spoken by those northern members of the Angle or English race who became subjects of the King of Soots, and who became the leading race, and their tongue the leading language of the country ; to which, however, another race, with whom the monarchy had originated, gave its name."