small fortified place, environed with a ditch, rampart, and parapet. The use of forts is to secure some high ground, or the passage of a river, to make good an advantageous post; to defend the lines and quarters of a siege, and the like. Forts are built of different figures and dimensions, according to the exigencies of the case. Some are provided with bastions, others with demi-bastions; some are of a square form, others pentagonal, and others again are stellated, having five or seven angles. See Fortification.

Vitrified Forts. This name has been given to certain remarkable ruins, situated for the most part on the tops of certain hills in the Highlands and northern parts of Scotland. They were first described, about the year 1773, by Mr Williams, an intelligent mineral surveyor. These singular structures derive their appellation of vitrified from the circumstance of the stones composing them presenting the appearance of having been melted or fused by means of fire; thus forming a solid mass of a glassy structure, somewhat resembling volcanic lava, or the refuse of a furnace. In form, size, and situation, they present every variety. Some of them are round or elliptical, whilst others are in the form of squares or parallelograms. In magnitude they vary from a few yards to some eighty or ninety in length, whilst their breadth differs in a proportional degree. The walls likewise vary much in thickness. Some of them are only two or three, and others are about twenty feet in breadth. In height they also differ considerably, having apparently in some instances been twelve feet, and in others not a third of that height. In one or two instances there are a series of walls, two or three in number, inclosing the same area of ground, with a space between each of the works sufficiently large to admit of active defensive operations on the part of those who occupied the place. Their vitrification is very irregular. Occasionally it does not extend a few feet above the ground on which the fabric stands, nor penetrate beyond the surface, whilst in a few instances it rises to the height of ten or twelve feet, and passes inwards to a considerable extent on both sides; and sometimes only isolated parts of the walls show traces of vitrification. They generally occupy commanding positions; but are also found on the seashore, and sometimes many miles inland. In general their structure displays nothing like regular masonry. A few of them are approached by regular causeways; and many are furnished with wells, an indispensable requisite for a garrison.

After the publication of Mr Williams's account, the ingenuity of the learned was turned to their probable origin, and many ingenious theories were hazarded on the subject. Some declared them to be of volcanic origin, whilst others contended that they were works of art. The most probable conjecture respecting the vitrification of these structures appears to be, that the ancient inhabitants of Britain, who were unacquainted with the use of mortar, discovered, probably by accident, that some rocks which resist the action of fire become fusible when subjected to a high temperature in contact with certain others; and that the knowledge of this fact led them to employ masses of such mixed rocks in their structures, the stones of which were then cemented together or vitrified, by heaping combustibles about them and setting them on fire.

Vitrified remains are of very frequent occurrence in Scotland, more particularly in the northern and north-western counties. Many of these have been minutely described in various works, to some of which we shall presently refer, and in this place shall merely give an account of one or two of the more remarkable of such remains, in order to illustrate their general character.

Dun MacSnoichain, which lies in Argyleshire, is thus described by Dr Macculloch. "It is situated on a small rocky hill, which forms a kind of island in the plain, of a narrow prolonged shape, and scarped all round, except at one extremity, which affords access to the summit and the fort. The height of this hill or rock above the plain seems to be about forty or fifty feet; and it is, even in the modern military sense, a strong position. It is important to remark, that the rock consists of limestone and slate intermixed, the plain itself being chiefly alluvial, and the nearest hill and rocks being of trap, and of that pudding-stone so well known to all travellers, which also abounds in the vicinity of Oban. That stone is itself formed of fragments of various trap rocks, and is remarkable for its ready fusibility, while the rock on which the fort stands is of an infusible nature. The fort itself is so contrived as to occupy nearly the whole summit, which is about 250 yards long, and consists of three distinct parallelogrammic enclosures. The dimensions of these are as follows, as nearly as could be measured by pacing. The outer is about thirty yards long and about twenty-four broad; the next is about thirty-seven, with a similar breadth; and that at the further extremity is about fifty-six yards in length, but being imperfect, it may formerly have been longer. Besides this, between the first and second works there is a transverse wall which reaches from the one precipitous face to the other, so as, when entire, to have cut off the communication from without to the two inner works. The circumferences of the two inner enclosures make collectively a line of about 260 yards, which, according to the modern military computation for a redoubt, would contain more than 500 men. The external work would dispose of about a hundred more. Hence it is plain that this must have been a military work of some consequence, as capable of holding a large garrison." He continues, "when it is said that the walls here or elsewhere are vitrified, it must not be supposed that they form a solid mass of glass or slag. That condition is very various in different specimens throughout Scotland, and if it is here more perfect than in many, it is less so than in some others. To speak more accurately, many of the stones which form the walls are more or less perfectly slagg'd or scorched; so that while some have been thus changed throughout, the surfaces only of others are affected, while others again, consisting of less fusible materials, are only burnt. A certain proportion has escaped the fire altogether, or has never been exposed to it; and if we may judge from the ruins, this has taken place chiefly towards the upper part of the wall. The general result, however, is, that in some parts the wall forms a solid mass, but of an irregular composition, consisting of scoria, slag, burnt stones, and stones scarcely altered, united together, but with vacant intervals; while in other places it is separable into lumps of various sizes, and into single stones."

That of Dunadear is described as follows:

"The hill of Dunadear, having an elevation of about 600 feet from the irregular plain on which it stands, with Vitrified Forts.

a steep acclivity all round, has a flat oval summit, which is entirely occupied by the enclosure, so as to form a strong military position. Though much ruined, and consequently obscured, having apparently been used as a quarry for building a more modern castle in the same spot, it is not difficult to trace either the dimensions or the disposition of the original work. The form is a parallelogram, of which one extremity is curved, so as to be nearly semicircular, and its longest side is about fifty-eight yards, the shortest being about twenty-four. The thickness of the wall seems originally to have been eighteen or twenty feet; although, from the state and nature of the ruin, it is impossible to be very accurate in this particular. The highest remaining portion is about six feet above the present surface; and if one foot be added for the increase of soil, and two for the loss which it has sustained at the summit, to be computed from the ruined part at its foot on each side, we shall have eight feet as the probable original altitude.

"The materials of the hill are chiefly gray granite, an infusible rock; but there are scattered in the surrounding plain blocks of a black variety, which, from containing hornblende, is very fusible. To pass over the obviously more modern ruins at this place, as not concerning the present question, there are at a certain stage down the hill the well-marked traces of a work which once seems to have encircled the whole. It is a kind of fortification well known to antiquaries as occurring frequently in the ancient British hill forts; and it resembles a modern military field work, as it consists of a single ditch and wall, the latter being formed of loose stones not vitrified. I consider this as part of the original defences, because a similar one is found on Noath.

"The materials in the vitrified wall are, as at Dun MacSnioclain, partly roasted without adhesion, and partly vitrified, or glazed or scorified, in a similar manner. It is easy to see that the dark granite forms the vitrified and scorified substances; but, not to enter on the more minute details, which rather concern the chemist and mineralogist than the antiquary, but which are very interesting to them, I shall only further remark, that wherever stones not capable of vitrification themselves have undergone this change, it has been produced by the alkali of the wood used in the process; whence the glazed surfaces of many unvitrifiable substances.

"Now I remarked that at Dun MacSnioclain the materials of the hill itself were not vitrifiable, but that a very fusible rock was present at a short distance, or scattered in fragments about the plain. The same is true here; and in both cases the forts are not erected out of the materials nearest at hand, which are infusible, but collected with considerable labour from a distance. It is hence evident that the builders of those works were aware of the qualities of these various rocks, and it is equally evident that they chose the fusible in preference to the infusible, although with a considerable increase of labour."

Among other vitrified forts more particularly deserving of notice, may be mentioned that upon the hill of Noath in Aberdeenshire; and the large one on the hill of Knockfarl, two miles west of Dingwall in Ross-shire.

Another of these forts is situated about a mile from Inverness, upon the hill of Craig-Phadrick (or Rock of Peter) at the eastern end of the Great Glen, and forming the termination of the high sandstone and conglomerate hills of Loch Ness. Craig-Phadrick is about 485 feet in height above the sea. The summit presents two vitrified walls quite round the area. The space within the inner wall is 80 yards long and 30 broad. It is now overgrown with wood and moss; but in 1812, when the late Mr Telford was engaged in the construction of the Highland roads and bridges, the interior was cleared out, and the vitrification minutely examined. Both the outer and inner ramparts are chiefly composed of a reddish coloured schistus, which seems to have been taken from the south-west end of the fort, where there is an opening that had apparently been occupied by this species of rock up to the common surface. The pieces of stone composing the walls are none of them large. They have been laid down without any order or regularity, and so carried up in this manner to within about two feet of the present top, where a stratum or crowning of small fragments of pudding-stone or conglomerate has been laid on, and by some means brought into a state of vitrification. The great mass of schistus composing the ramparts is quite loose and not vitrified, but nearly the whole of it bears evident marks of having been exposed to a considerable degree of heat, as appears from its yellowish red or brick colour. In the north-west ramparts, especially the outer one, the vitrification is wanting for a considerable space, but the remaining schistus bears all the marks of that found under the vitrification. The most practical-looking conjecture is that over the wall of schistus work was placed a thick layer of timber, faggots of furze or heath, and then a stratum of conglomerate stones laid over all, when the timber, &c., being set on fire would produce the desired vitrification, and give to the lower work the scorched appearance it possesses. Seaware, of which there is abundance at hand, may have been used as a flux. The principal entrance into the fort appears to have been at the north-east end, which was defended by the strongest ramparts, and by a deep trench. The passage over the trench is by a solid dyke composed of similar materials to the ramparts. The entrance at the south-west end is not so well defined, the top of the inner rampart there being nearly as high as the adjacent parts. The chasm or passage through the rock below the outer rampart to the deep hollow which separates Craig-Phadrick from the chain of mountains on the southwest appears to be natural, not artificial, as was conjectured by the late Mr Tytler of Woodhouselee. Such appearances are not uncommon. The four stones or boulders lying on the rocky platform near the brink of this passage are certainly fragments of a larger rock that must once have occupied the platform, and were not placed there, as Mr Tytler supposed, to stop the progress of an invading army. The largest of the boulders is about 10 or 11 tons weight, and a whole regiment might have passed before it could have been put in motion by manual labour, while the other stones are too small to have given any serious obstruction to an enemy. It has been stated that there is a well of about 6 feet in diameter at the summit of Craig-Phadrick, in the centre of the inner area, but this is a mistake. There is no water nearer than a spring about 300 feet perpendicular below the summit of the hill. From the scarcity of water and the want of room, cattle could not have been admitted for any length of time into the fort, and it is probable that at the date of these erections the principal animal food of the people was that procured by the chase and hunting in the forests. The theory that the vitrified forts were merely beacons to warn the country of approaching invasion, seems inadmissible. The circular ramparts and vitrification are too regular to guarantee this supposition. They may, however, have been used in the middle ages as sites for alarm fires; and Craig-Phadrick is within sight of a chain of similarly vitrified structures communicating over the country; but there are others (in Nairnshire for example) which could not have answered for this purpose. They are much more likely to have been the fortified residences of petty chiefs at a period before the use of lime cement was known in the north of Scotland—perhaps ages before the Scandinavians

1 This, we presume, refers to the remains of an oblong tower constructed of lime, mortar, stone, and fragments of the earlier vitrified fort, to which the opponents of Dr Macculloch ascribe a more modern date than belongs to the rest of the structure. were possessed of knowledge requisite for equipping fleets powerful enough to give much disturbance to their southern neighbours. The baronial castles and forts of the middle ages are frequently found in situations nearly as inconvenient for domestic comforts as the more ancient vitrified forts.

In the parish of Meigle, Perthshire, there is a hill called Barryhill, which appears to have been strongly fortified, though without any attempt at cementing stones; but at the south-east extremity of the fort there was a vitrified mass in the form of a wall or dyke occupying the bottom of the trench between the summit and the outer rampart.

Near Creich, in the county of Sutherland, there are some vitrified remains; as also near the church of Anwoth, in the county of Kirkcudbright; and in the island of Bute, in the parish of Kingarth, there is a vitrified fort. In Cantyre, at the entrance of the bay of Carradale, on a small island, about a rood of ground is enclosed by vitrified masses. Others have been observed in Argyleshire, particularly one on the hill of Dunskeig, which commands the entrance of Loch Tarbert.

On the hill of Laws, near the village of Sturdevuir, a few miles north-east from Dundee, there is a vitrified fort. About four miles east from Forfar is the castle-hill of Finhaven, the vitrifications on which have been compared by Dr Anderson to the effects of fire in a limekiln.

It is impossible in this place to point out all the vitrified ruins, amounting to about fifty, and extending over Perthshire, Forfarshire, Kincardineshire, Aberdeenshire, Banffshire, Morayshire, Inverness-shire, which contains an immense number, Ross-shire, Cromartyshire, Argyleshire, Buteshire, Berwickshire, and Galloway. Dr Hibbert, in a paper read to the Society of Antiquaries of Scotland in 1831, informs us that he had discovered masses of vitrified matter at Elsness in Sanday, one of the Orkney islands. Of these curious remains, which he calls vitrified cairns, or beacon cairns, he counted more than twenty. They are of a round shape, from three to five yards in diameter, and elevated from two to three feet above the surface of the ground. The stony fragments of which they are composed appear to have been collected from the beach, and consist of an argillaceous schist. Their fusibility they derive chiefly from the feldspar, or rather the alkali, which they contain. For further information respecting vitrified forts and similar remains of antiquity, see Macculloch's Highlands and Western Isles; Archaeologia Scotiae; Transactions of the Society of Antiquaries of Scotland, vol. iv., &c., &c.

FORT-AUGUSTUS, FORT-GEORGE, AND FORT-WILLIAM. See INVERNESS-SHIRE.