"The Crannoge of which I am now to give an account was discovered by me in the summer of 1812, and is thus described in a letter, dated 13th February 1813, which I wrote to the late James Knox, Esq. of Glasgow, who immediately sent it to his friend, George Chalmers, Esq., author of _Caledonia_:--'There is a small mossy lake, called Dhu-Loch, situated in a narrow valley in the middle of that strong tract of hill-ground extending from the Dun-hill of Barone to Ardscalpsie Point, to which valley, it is said, the inhabitants of Bute were wont to drive their cattle in times of danger. I remember, when a schoolboy, to have heard that there were the remains of some ancient building in that lake, which were visible when the water was low; and happening to be in that part of the island last summer, I went to search for it. I found a low green islet about twenty yards long, which was connected with the shore, owing to the lowness of the water, after a continuance of dry weather. Not seeing any vestiges of stone foundations, I was turning away, when I observed ranges of oak piles, and on examination it appeared that the edifice had been thus constructed. "The walls were formed by double rows of piles, 4-1/2 feet asunder, and the intermediate space appears to have been filled with beams of wood, some of which yet remain. The bottom had been filled up to the surface of the water with moss or turf, and covered over with shingle, or quarry rubbish, to form a floor. The ground-plan was a triangle, with one point towards the shore, to which it had been connected by a bridge or stage, some of the piles of which are still to be traced." Mr. Chalmers, in his letter to Mr. Knox of 26th April 1813, relative to the above communication, says:--"It goes directly to illustrate some of the obscurest antiquities of Scotland--I mean the wooden castles--which belong to the Scottish period when stone and lime were not much used in building. I will make proper use of this discovery of Mr. Mackinlay." On revisiting this island in 1826, Mr. Mackinlay observed "an extension of the fort on the south-east corner, formed by small piles and a frame-work of timbers laid across each other, in the manner of a raft." LOCH QUIEN, BUTESHIRE. There was another insular fort in Loch Quien, which Mr. Mackinlay describes as a crannog; but not being able to get on the islet, his measurements are conjectural, and need not be further referred to. He then states that two rows of piles extended obliquely to the shore of the lake, between which the ground was covered with flat stones, "not raised like a causeway, but rather seeming to have been used as stepping-stones." DR. ROBERTSON'S VIEWS ON SCOTTISH CRANNOGS.