The castles of the Hebrides, many of which are standing, and many ruined, were always built upon points of land, on the margin of the sea.  For the choice of this situation there must have been some general reason, which the change of manners has left in obscurity.  They were of no use in the days of piracy, as defences of the coast; for it was equally accessible in other places.  Had they been sea-marks or light-houses, they would have been of more use to the invader than the natives, who could want no such directions of their own waters:  for a watch-tower, a cottage on a hill would have been better, as it would have commanded a wider view.

If they be considered merely as places of retreat, the situation seems not well chosen; for the Laird of an Island is safest from foreign enemies in the center; on the coast he might be more suddenly surprised than in the inland parts; and the invaders, if their enterprise miscarried, might more easily retreat.  Some convenience, however, whatever it was, their position on the shore afforded; for uniformity of practice seldom continues long without good reason.

A castle in the Islands is only a single tower of three or four stories, of which the walls are sometimes eight or nine feet thick, with narrow windows, and close winding stairs of stone.  The top rises in a cone, or pyramid of stone, encompassed by battlements.  The intermediate floors are sometimes frames of timber, as in common houses, and sometimes arches of stone, or alternately stone and timber; so that there was very little danger from fire.  In the center of every floor, from top to bottom, is the chief room, of no great extent, round which there are narrow cavities, or recesses, formed by small vacuities, or by a double wall.  I know not whether there be ever more than one fire-place.  They had not capacity to contain many people, or much provision; but their enemies could seldom stay to blockade them; for if they failed in the first attack, their next care was to escape.

The walls were always too strong to be shaken by such desultory hostilities; the windows were too narrow to be entered, and the battlements too high to be scaled.  The only danger was at the gates, over which the wall was built with a square cavity, not unlike a chimney, continued to the top.  Through this hollow the defendants let fall stones upon those who attempted to break the gate, and poured down water, perhaps scalding water, if the attack was made with fire.  The castle of Lochbuy was secured by double doors, of which the outer was an iron grate.

In every castle is a well and a dungeon.  The use of the well is evident.  The dungeon is a deep subterraneous cavity, walled on the sides, and arched on the top, into which the descent is through a narrow door, by a ladder or a rope, so that it seems impossible to escape, when the rope or ladder is drawn up.  The dungeon was, I suppose, in war, a prison for such captives as were treated with severity, and, in peace, for such delinquents as had committed crimes within the Laird’s jurisdiction; for the mansions of many Lairds were, till the late privation of their privileges, the halls of justice to their own tenants.