Primary Sources
Notes on Gaelic Title
Gleus not found but we have 050 A Glase C1; 127 A Glass C2; 146 A Glas C2. Suggested to be English spellings for Gaelic gleus, and interpreted as ‘[finger/ tuning] exercise’. Cf. A’ Ghlas Mheur (132); also Deuchainn Ghléusaidh, an expression for a tuning prelude. See S. Donnelly, ‘Feaghan Geleash’. Ceol Tire, 25 (1984) pp 5-6, 11-12; R.D. Cannon, ‘Gaelic names of pibrochs: a classification,’ Scottish Studies, 34 (2000-2006), pp 20-59.
I think there is something arbitrary about assuming ‘A Glas’ (literally ‘THE lock’) to be a mistake for ‘gleus’ (a tuning phrase). Not only does it ignore the definite article – why would a collection such as Colin Campbell’s have four tunes all named ‘The Tuning Prelude’?, but it ignores the recorded colloquial use of the word ‘glas’ in Gaelic – see Dwelly, ‘A’ghlas ghuib’, the mouth-lock, or a remark which leaves one speechless.- which is figurative. A possible literal meaning is ‘grip’; of which several varieties were popular in the past: the mason’s grip, the Horseman’s grip, and possibly one used by fighters about to engage the enemy (see Dr. R.Ross, address to the P.S. 2009 Pitlochry – http://www.piobaireachd.co.uk/wp-content/uploads/2012/04/2009session1.pdf ).