LECTURE VI. (NOVEMBER 2, 1881.) LAKE-DWELLINGS, HILL-FORTS, AND EARTH-HOUSES.
A Broch like that of Clickamin (see the Frontispiece), situated upon an island in a loch, accessible by a causeway from the island to the shore is practically a lake-dwelling. But there are many defensive structures occupying similar positions which are not Brochs, although they are often constructed of stone. Most of them are now in such a ruinous condition that it is impossible to say what may have been the precise nature of their form and architectural construction.
[Illustration: Fig. 244.—Defensive structure on an island in the Loch of Hogsetter, Whalsay, Shetland. (From a Sketch Plan by Dr. Arthur Mitchell.)]
In the Loch of Hogsetter, in the island of Whalsay, in Shetland, there is a small island containing a defensive structure of dry-built masonry (Fig. 244) which is plainly not a Broch.[93] The structure occupies the greater part of the available surface of the island, and its form has evidently been determined by the form of the island. It consists of a dry-built wall of stones with a minimum thickness of 3 to 4 feet, enclosing an oblong oval of about 70 feet by 75 feet. A causeway, 33 yards in length, has been constructed to give access to the island from the shore, and on the side next the causeway the enclosing wall is amplified so as to admit of the construction of a doorway, flanked on each side by a chamber, as seen in the detached work protecting the entrance to the island of Clickamin. This part of the construction is solidly built, and the chambers, which are placed to right and left of the entrance passage, occupy the interior of a somewhat rectangular expansion of the wall, measuring about 20 feet by 12 feet, and now only about 8 feet high. When Low visited Whalsay in 1774, this part of the construction was 15 feet high, and the chambers and their entrances were quite entire. They were beehive roofed, the entrances going straight through the back wall from the enclosed area. The main entrance, which was 2½ feet wide and 4½ feet high, was covered by the masonry which joined the two sides of the construction over its lintels, and at about two-thirds of its length inwards there were checks for a door and the usual bar-holes on either side. Dr. Mitchell states that above the two lower chambers there appear to have been other two forming a second tier, but as Low did not observe them, and no trace of a stair or other access to the upper level now remains, it seems possible that they may have been chambers of construction, or merely vacancies left to lighten the weight on the roofs of the chambers below. Apart from the peculiarity of its chambers, which are unlike the guard-chambers of the Brochs in having their entrances opening to the enclosed space and not directly opening into the passage, this structure has more affinities with the stone cashels than with the Brochs. Like them it adapts its form to the space in which it is situated, and like them it consists of a simple rampart with cells in the thickness of the wall. The wall is low, and of no great strength, and like the wall of a cashel is merely meant to add to the defensibility of a naturally defensive position. The special peculiarities of this defensive construction are, that it is a dry-built structure which is not a Broch but a cashel, and that it is situated on an island in a loch and rendered accessible by a causeway. The island is of natural formation, and has been thus utilised, because of its suitability for defensive purposes.