joists, on which rested the floors, which were almost always of wood. In the uppermost of these stories the wall is perforated by two, four, five, six, or eight apertures, but most usually four, which sometimes face the cardinal points, and sometimes not. The lowest story, or rather its place, is sometimes composed of solid masonry, and when not so, it has never any aperture to light it. In the second story the wall is usually perforated by the entrance doorway, which is generally from eight to thirty feet from the ground, and only large enough to admit a single person at a time. The intermediate stories are each lighted by a single aperture, placed variously, and usually of very small size, though in several instances, that directly over the doorway is of a size little less than that of the doorway, and would appear to be intended as a second entrance.
ROUND TOWER ON DEVENISH ISLAND.
"In their masonic construction they present a considerable variety: but the generality of them are built in that kind of careful masonry called spawled rubble, in which small stones, shaped by the hammer, in default of suitable stones at hand, are placed in every interstice of the larger stones.
