James Farrer, Notice of Runic Inscriptions Discovered during Recent Excavations in the Orkneys
“ In each angle of the central chamber stands a large buttress, doubtless intended to strengthen the walls, and support them under the pressure of their own weight, and that of the mass of earth with which the whole was covered. These buttresses vary somewhat in dimensions, but they are on an average about 3 feet square at the base, and from 9 to 10 feet high, with the exception of one which is only 8 feet high. In each buttress one side is formed by a single slab. The walls of the chamber are built with large stones, which generally extend the whole length of the wall. ”
