While clearing out the refuse-heap, the position of the surrounding piles immediately to the left of the original trench was readily ascertained to be arranged in three or four circles. With these as guides, it was an easy matter for the workmen to clear away the soil right round the central portion of the crannog without the necessity of constant supervision. The surface soil, which consisted of fine clay, varying in depth from about 6 inches at the centre of the mound to 2 feet beyond the outer circle of stockades, was first wheeled away, and, as no relics were expected here, there was no time wasted in searching for them. Afterwards the dark heterogeneous under stratum of débris was carefully removed from above the wood-work and examined, though not with the same care as the contents of the refuse-heap. Here, however, a few important relics were discovered, among which are an ornamented gold spiral finger-ring, a small earthen crucible, and some fragments of pottery. Having completed this broad annular trench, the débris remaining on the central portion was taken away, but, contrary to expectation, nothing was found in it beyond the evidence of a few fireplaces, some slag, and one or two large wooden pins. [Illustration: Fig. 188.--General View of Buston Crannog, looking northwards. The water in foreground marks the position of Refuse-bed. (_From a Photograph by Mr. Lawrie._)] _Structure of Island._--Notwithstanding the havoc committed on the wood-work of the crannog by long exposure to atmospheric agencies before it finally sunk under the protective influence of the muddy water, and subsequently, by the ruthless hands of the agriculturist, there still remained sufficient materials to give one not only a general, but particular and instructive notion of the mechanical principles on which the island was constructed. Its substance, as far as could be ascertained by digging holes here and there, was made up of layers of the stems of trees, chiefly birch; intermingled with which were occasionally found various other materials, such as brushwood, heather, moss, soil, and large stones. Penetrating deeply this heterogeneous mass, towards its margin, were numerous piles, forming a series of concentric and nearly circular stockades, which were separated from each other by an interval of 4 or 5 feet. On the south side there were four distinct circles to be seen, but on the north only three could be detected, as the third outermost appeared to have merged into the external one; and, in accordance with this diminished number of circles, the breadth of the stockaded zone also diminished. The piles in the inner circle, which were strongly made, and showed evidence of having been shaped and squared by sharp-cutting instruments, were uniformly arranged at a distance of from 4 to 5 feet, and enclosed an area more of the form of an ellipse than a circle (measuring 61 feet by 56), while those in the second and third