SCOTT began to work on "The Heart of Mid-Lothian" almost before he had completed "Rob Roy." On Nov. 10, 1817, he writes to Archibald Constable announcing that the negotiations for the sale of the story to Messrs. Longman have fallen through, their firm declining to relieve the Ballantynes of their worthless "stock." "So you have the staff in your own hands, and, as you are on the spot, can manage it your own way. Depend on it that, barring unforeseen illness or death, these will be the best volumes which have appeared. I pique myself on the first tale, which is called 'The Heart of Mid-Lothian.'" Sir Walter had thought of adding a romance, "