which lie scattered at their bottoms. Their diameter, in general, is from twelve to eighteen feet; but some were far less, not exceeding five feet. On the small area of the top had been a group of towers or cells, like the former—one in the centre, and five others surrounding it.”[19] Some of our northern forts have been, however, on a greater scale. Of the White Caterthun in Strathmore, General Roy says, “The most extraordinary thing that occurs in this British fort is the astonishing dimensions of the rampart, composed entirely of large loose stones, being at least twenty-five feet thick at top, and upwards of one hundred at bottom, reckoning quite to the ditch, which seems, indeed, to be greatly filled up by the tumbling down of the stones. The vast labour that it must have cost to amass so incredible a quantity, and carry them to such a height, surpasses all description. A simple earthen breastwork surrounds the ditch; and beyond this, at the distance of about fifty yards on the two sides, but seventy on each end, there is another double intrenchment, of the same sort, running round the slope of the hill. The intermediate space probably served as a camp for the troops, which the interior post, from its smallness, could only contain a part of. The entrance into this is by a single gate on the east end; but opposite to it there are two leading through the outward intrenchment, between which a work projects, no doubt for containing some men posted there, as an additional security to that quarter.”[20]