The round house had a domed roof. On the other hand, the "arbor" abode resembled, in the words of the English, "the arbories in our gardens in England." The roofs of such habitations were arched in the form of a tunnel vault. [Illustration: Indian dwellings in Va.] The construction of the wigwam was generally a framework of saplings or young trees spaced nearly vertically in the ground at regular intervals, and bowed at the top, to make the dome or tunnel vault, as the case might be. Although the saplings were usually tied securely at the top with "withes"--which are flexible twigs,--and with roots, vines, reeds, or bark strips, some dwellings had young trees long enough to have both ends stuck in the ground, so that nothing had to be tied at the top. Ordinarily for strength the walls of such homes were battered or sloped inward at the top. At all events, cross pieces of small poles, running horizontally, were fastened to the saplings in order to serve as braces and as supports for the various kinds of curtain material employed by the Indians--materials like woven-grass mats, bark, and skins. One of the curious features of some of these arbor houses which the writer does not believe to have been elsewhere described before, is the use of a kind of "lunette" or half-moon window, of multiple lights, on the long side of a domicile. Such a feature gave additional ceiling space and more headroom. If lunettes were employed opposite each other on each side of a wigwam roof, for which arrangement we have no evidence, the roof must have resembled what we call a "cross-vault." It is interesting that lunettes and cross-vaults of masonry were employed by the Romans and the Goths of Europe. That the Indian had lunettes and probably had cross-vaults was a mere coincidence. It seems that most of the arbor houses averaged twelve feet wide and eighteen long, according to finds made in excavations. Even so, many lodgings were longer. Some were over seventy feet, and were divided into separate compartments by interior partitions of saplings and mats. [Illustration: Two arbor-houses in Va. Garden Listening post Framing detail Path Border] For wigwams the covering mats were woven with long rushes or grasses, and for the most part extended from the top of the house to the ground. They were usually three or four feet wide and in length eight or ten feet, and were stitched together or to the framework of the dwelling. Furthermore, mats were not the only covering employed. Bark of cedar, oak, or hickory was used, and made a thicker and better insulated material than mats, which in summer permitted the interiors to heat up like stoves. The bark was stripped off the tree in great flakes, and was laid so closely together that no rain could enter. Some wigwams had a combination of mat and bark, like mat walls and bark roofs. And sometimes animal skins were used as coverings.