William Borlase was a Cornish antiquary, who was born in 1696, and died on August 31, 1772; one year after Scott was born. His publications include “Antiquities of Cornwall”, “Observations on the Ancient and Present State of the Islands of Scilly”, and “Natural History of Cornwall”. Scott referred to Borlase in the notes to his “Marmion”.
Note VI.
The battled towers, the donjon keep. -P- 93It is perhaps unnecessary to remind, my readers, that the donjon, in its proper signification, means the strongest part of a feudal castle; a high square tower, with walls of tremendous thickness, situated in the centre of the other buildings, from which, however, it was usually detached. Here, in case of the outward defences being gained, the garrison retreated to make their last stand. The donjon contained the great hall, and principal rooms of state for solemn occasions,
and also the prison of the fortress; from which last circumstance we derive the modern and restricted use of the word dungeon. Ducange {voce Dunjo) conjectures plausibly, that the name is derived from these keeps being usually built upon a hill, which in Celtic is called' Dun. Borlase supposes the word came from the darkness of the apartments in these towers, which were thence figuratively called Dungeons: thus deriving the ancient word from the modern application of it.