As soon as the problem was thus virtually reduced to a negotiation between the American commissioners and Lord Shelburne's ministry, the air was cleared in a moment. The principal questions had already been discussed between Franklin and Oswald. Independence being first acknowledged, the question of boundaries came up for settlement. England had little interest in regaining the territory between the Alleghanies and the Mississippi, the forts in which were already held by American soldiers, and she relinquished all claim upon it. The Mississippi River thus became the dividing line between the United States and the Spanish possessions, and its navigation was made free alike to British and American ships. Franklin's suggestion of a cession of Canada and Nova Scotia was abandoned without discussion. It was agreed that the boundary line should start at the mouth of the river St. Croix, and, running to a point near Lake Madawaska in the highlands separating the Atlantic watershed from that of the St. Lawrence, should follow these highlands to the head of the Connecticut River, and then descend the middle of the river to the forty-fifth parallel, thence running westward and through the centre of the water communications of the Great Lakes to the Lake of the Woods, thence to the source of the Mississippi, which was supposed to be west of this lake. This line was marked in red ink by Oswald on one of Mitchell's maps of North America, to serve as a memorandum establishing the precise meaning of the words used in the description. It ought to have been accurately fixed in its details by surveys made upon the spot; but no commissioners were appointed for this purpose. The language relating to the northeastern portion of the boundary contained some inaccuracies which were revealed by later surveys, and the map used by Oswald was lost. Hence a further question arose between Great Britain and the United States, which was finally settled by the Ashburton treaty in 1842. [Sidenote: 2. Fisheries; commercial intercourse;]