a ground plan of the work, as well as I could determine it by pacing, and without tools to clear away the sod. Those who have seen similar works know how completely they are sometimes covered with the soil; a circumstance which, as I have just noticed, perhaps more decidedly than any other, marks their high antiquity. Imperfect however as their traces generally are, the drawing will serve to show a very peculiar form in that which is the subject of the present paper, and a plan differing much from the uniformity of structure and rudeness of design which have been supposed to distinguish these works.
The long narrow hill on which it stands is nearly precipitous along three quarters of its circumference; at the other end it rises from the plain with a very accessible acclivity. By inspecting the plan, it will be seen that a series of parallelogramic works have been constructed so as nearly to cover the principal and precipitous part of it to the very edge. The greater portion of the hill being thus occupied by two of these works, the strongest part was cut off by a wall from the more accessible end, thus forming a sort of citadel or place of retreat at the last extremity, a practice very common in the ancient peninsular fortifications of Cornwall, in Castle Trereen for example, and in at similar castle at Zenor. To occupy and defend the vulnerable side of this position, the outer work appears to have been placed without the principal area, that from it the enemy might be seen and opposed in every part of his ascent. This disposition bears incontrovertible marks of military design and experience. Were a modern engineer to defend Dun Mac Sniochain, he could do little more than build a fort to occupy the ground and contain his men, erecting an out-work to command the approach.
I have thus particularly detailed the military relations of this