Those mound dwellings, or Picts’ houses, may seem to us a very strange form of house to live in. Where can we find to-day houses of such a type, and with so very inconvenient a form of entrance? The Eskimos, as travellers tell us, are in the habit of building just such houses with blocks of snow, and they find this the best type in the extreme cold of their Arctic climate. Possibly the Picts’ house type of dwelling was used in Orkney and in other places for similar reasons. [Illustration: _Polished Stone Celts._] The brochs, or Pictish towers, as they are also called, are buildings of a different kind, which are also fairly common in Orkney. They are probably of later date than the Picts’ houses. Considerable skill, as well as co-operation in labour, must have been required for their erection. The most complete broch in existence is that of Mousa in Shetland. Of those which are found in Orkney, only the lower portions now remain. Over seventy such ruins have been examined, the best specimens being in Evie (Burgar), Birsay (Oxtro), Harray, Firth (Ingashowe and Stirlinghowe), St. Ola (Birstane and Lingro), St. Andrews (Dingishowe and Langskaill), Burray (East and West Brough), South Ronaldsay (Hoxa), Shapinsay (Borrowston), and Stronsay (Lamb Head). [Illustration: _Plan of Chambered Mound, Wideford Hill._ _b_, Entrance. _c_, Blind Passage.] [Illustration: _Chambered Mound, Wideford Hill._ Section on line _a, a_ of plan.] The typical broch is a large round tower, fifty or sixty feet in diameter, and probably as much in height. The wall is about fifteen feet thick, and solid at the base, except for some vaulted chambers which are made in it. Higher, the wall is hollow, or rather consists of an outer and an inner wall, with a space of four or five feet between them. This space is divided into a number of stories or galleries by horizontal courses of long slabs of stone, which form the roof of one story and the floor of that above it, and at the same time bind the two walls firmly together. A stairway gives access to the various stories, and light is admitted by small windows opening into the interior space of the tower, no windows being made in the outer wall. A single door in the lower wall forms the only entrance to the inner court of the broch. These towers were probably constructed for the purpose of defence, and against a primitive enemy they would serve as well as did the castles of a later age before the invention of gunpowder. Indeed, we read of the broch of Mousa being actually used as a fort in the time of the Norsemen. Who the builders of these towers were we cannot discover. They are undoubtedly very ancient; yet their builders and occupiers were by no means savages. From the remains which have been found in them we learn that they were used by a people who kept domestic animals, who cultivated the ground, and who could spin and weave the wool of their flocks into cloth. No weapons of the Stone Age are found in the brochs.