FORT, in the military art, a small fortified place, environed on all sides with a ditch, rampart, and parapet. Its use 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 made of different figures and dimensions, according as the peculiar nature of the ground requires. 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. A fort differs from a citadel in this, that the latter is built to command some town.

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 discovered about the year 1773, by Mr Williams, an intelligent mineral surveyor, who published an account of them some time afterwards. 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. The single fact of their vitrification is the only characteristic applicable in a general sense to the whole of these forts. 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, as might have been expected, 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, enclosing 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. Sometimes only isolated parts of the walls show traces of vitrification, and that too but on one side; in other instances the process appears to have been completed with elaborate care, as the effects of the heat extend externally and internally over the greater part of their surfaces. They are for the most part placed, not upon the highest elevation of the country where they are [7:9:755]situated, but generally in a commanding position; and they are found sometimes upon the sea-shore, and sometimes many miles inland. In general their structure displays nothing like regular masonry: that is, the stones have not been hewn into symmetrical shapes and cemented together, as is the case in the more modern structures of the same country. A few of them have regular causeways leading up to them, and many are furnished with wells, an indispensable requisite for a garrison. Such is a general description of these singular erections, which have for more than half a century excited so much curiosity and interest.

After the discovery of Mr Williams, the ingenuity of the learned was turned to their probable origin, and several theories and conjectures were hazarded by various individuals upon the subject. By one party they were declared to be of volcanic origin, whilst another contended that they were works of art. Of the latter opinion was Mr Williams himself, who not only declared them to be the result of human ingenuity, but speculated upon the manner in which they were constructed. But before adverting to any of the theories which have been advanced, we shall give a description of the most remarkable of these forts, and this, as far as possible, in the language of those individuals by whom they were examined.

Dun MacSniochain, which lies in Argyleshire, is very fully described by Dr Macculloch.^[1. Macculloch’s Highlands and Wettern Isles, vol. i. n. 283. ] “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 pccess 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 puddingstone 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 parallelogramic 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 farther 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.” The doctor goes on to show the eligibility of this place as one of military defence; and observes, that the walls were probably twelve feet thick. 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 slagged or scorified; 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.”

The next, vitrified fort described by Dr Macculloch is that of Dunadeer.

“The hill of Dunadeer, having an elevation of about 600 feet^[2. This is an exaggeration. It is only about 400 feet high at the moat. ] from the irregular plain on which it stands, with 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 grey 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,^[3. This, we presume, refers to tha remains of an oblong tower constructed of ume, 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. ] 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 Noatħ.

“The materials in the vitrified wall are, as at Dur MacSniochain, partly roasted without adhesion, and partly vitrified, or glazed or scorified, in a similar manner. Il is easy to see that the dark granite forms the vitrified and scorified substances; but, not to enter on the mon minute details, which rather concern the chemist and mineralogist than the antiquary, but which are very inte resting to them, I shall only further remark, that where-ever stones not capable of vitrification themselves hav< undergone this change, it has been produced by the alkal of the wood used in the process; whence the glazed sur faces of many unvitrifiable substances.

“Now 1 remarked that at Dun MacSniochain the ma [7:9:756]terials 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.”

The next vitrified fort of consequence is that upon the hill called Noath, or Top of Noth, in Aberdeenshire. It is thus described by the same author:

“This mountain is the highest point of its own ridge, rising to the height of about 1800 feet above the level of the sea, and of 300 above any part of the surrounding ground, with a steep acclivity. The summit is a plain; and, as at Dunadeer, that plain seems to have regulated the size of the fort, as it occupies the whole space; an arrangement which is equally found at Dun MacSniochain. Nothing can more clearly prove the military and common design of all these works, since they vary in form and size according to the ground they stand on, and are so contrived, just as a military work would be in the hands of a modern engineer, that they may command all the points of access, and prevent the enemy from advancing any where under cover. . . . The area on Noath is nearly twice as large as that on Dunadeer, yet the same system is followed; and in Dun MacSniochain, as I already showed, though the mode of occupying the ground is different, the principle of a complete command is equally kept in view; while other variations are made for the purpose of conforming to the peculiar shape of the hill.”

“The enclosure on Noath is a long parallelogram of about ninety by thirty-two yards, slightly rounded at the angles; and it contains a well. Hence also we may conclude that this was a station and a garrison. An entire deficiency of the wall at the eastern side seems to indicate the entrance or gateway; a notion confirmed by its being continuous with a spacious causeway that extends a considerable way down the hill. That connexion also leads us to conclude that this causeway was not a posterior work, but that it originally belonged to the fort. It is made of laid stones, of considerable bulk, with great care and strength, resembling a Roman road; and it is remarkable that a similar causeway leads to the fort of loose stones on the top of Ben-na-chie.

“At Noath, too, as at Dunadeer, there is a similar fieldtrench and wall, or outwork, on the declivity of the hill; and, though much obscured, it seems also to have formerly surrounded the whole. In both cases it seems to have been intended as a covered-way, to retard the attack on the body of the place. The vitrified enclosure is far more perfect here than in any of these works in Scotland; and it is infinitely more remarkable, since, being unencumbered with soil and vegetation, scarcely even bearing a lichen, we see at a glance the whole effect of its blackness, its bulk, its regularity, and its extent. We may indeed wonder how any one could have imagined such a work the produce of a volcano, arid not less how any one capable in the least degree of observation or reasoning could have conceived it the effect of beacon-fires.

“The parts of the wall which have been most perfectly vitrified are, as might have been expected, the most entire: where highest, they measure eight feet from the ground, and the accumulation of soil at the base would justify the addition of two or perhaps three feet more in some places. That rubbish prevents the breadth from being correctly estimated, but this seems, as at Dunadeer, to have been eighteen or twenty feet. And if from that rubbish we may form an estimate of the total height of the wall before dilapidation, and before the growth of soil below, it may probably be taken at twelve feet. I must also remark, that the fallen rubbish, where the standing and vitrified part is eight feet high, consists of unvitrified stones; so that here, as at Dun MacSniochain, and in other examples, the wall, after having been vitrified to a certain height, seems to have been raised by some courses of dry masonry to its total altitude.” The state of the various materials which have been here exposed to the fire is so similar to that of those belonging to Dun MacSniochain and Dunadeer, that it is unnecessary to repeat the description.

On the hill of Knockfarril, which lies to the south of the valley of Strathpeffer, two miles west from Dingwall in Ross-shire, there is a vitrified fort. It is a remarkable one, both on account of its size, and because it was one of those which arrested the attention of Mr Williams, the discoverer of these structures. The hill of Knockfarrii forms part of a double ridge which bounds the valley of Strathpeffer on the south, and separates it from the valley of the river Conan. The sides of the hill are steep, but at the eastern and western extremities the ascent is comparatively easy. The area upon the top is about a hundred and thirty-five yards in length by about forty-five yards in medium breadth, and is a good deal inclined towards the west. Round the area, and close to the edge of the hill, are found masses of stones cemented together by melted matter, and irregular both in position and in size. The vitrification is superficial, extending only a short way amongst the stones. According to Mr Cardonnel, one of the earliest inspectors of this place, “the enclosure is a hundred and twenty feet long and forty broad within the walls, strengthened on the outside with works at each end. A range of habitations seems to have been erected against, or under the shade of, the outward wall, of which those on the south side seem to have been higher and larger than those on the north. There are two wells in the middle, which, on being cleared out, filled with water. On the skirts of the hill to the south are many detached buildings, which, from the stratum of dung found on removing the ruins, appear plainly to have been used for securing the cattle. This place seems to have been anciently of consequence, and the residence of some powerful chief, from a road which leads through the hills to the north-west sea. To the east of the works are a number of vitrified ruins, extending for a considerable way along the ridge of the hill. The end next the fort seems to have joined the outer wall, and consisted either of two parallel walls, closed above, with a passage between them under cover, or a high wall broad enough to walk on. In this wall there is the vestige of a break about the middle, over which a bridge has been laid, to be drawn up or removed as occasion might require.”

Mr Williams caused several cuts to be made across the area in different places, in which, Sir George Mackenzie^[4. Article l’onrs, VιτniriED, in Edinburgh Encyclopaedia. ] observes, a considerable quantity of rubbish is to be seen· “This rubbish,” says he, “appears to have been collected for the purpose of extending or forming the area on the top; and it would seem that much labour had been bestowed in accomplishing in this manner what mightappa-rently have been effected more easily by cutting down part of the summit.” The vitrified masses appear in many instances to have been displaced; and it seems pretty evι∙
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dent that the rampart was originally constructed with as much regularity as the nature of the materials would admit, both in order to render it more durable, and also to make it serve the purposes of defence.

The fort next in importance to that of Knockfarril is situated upon the hill of Craig-Phaidrick, near Inverness, “which,” according to Cardonnel, “has this peculiar circumstance, that there appears to have been two vitrified walls quite round the area. The inner one seems to have been very high and strong, the outer wall but low; probably the space between was intended for securing their cattle, as there are no remains of dry-stone buildings, such as are found near the rest. Several parts of this outer wall appear quite entire, sticking to the firm bare rock, where it was first run. The area within the inner wall is near eighty paces long and twenty-seven broad." Of this fort we have an account by Mr Tytler, afterwards Lord Woodhouselee. The hill itself is a small conical eminence, forming the eastern extremity of that ridge of mountains which bounds Loch Ness on the north-west side. It is situated about a mile to the north of Inverness, and is accessible on two different quarters, namely, the west and south-east; the former affording entrance by a narrow level ridge joining the hills on Loch Ness, and the latter by an easy ascent from the high ground above Inverness. On approaching the hill from the west, the traveller first meets with a road cut through the rock from the bottom to the top, in most places ten feet broad and nearly as many deep, winding, for about seventy feet, in an easy serpentine direction, by which he gains an ascent over a steep rock otherwise quite inaccessible from that quarter. In ascending by this road there appears, towards the middle, on the right hand, a small platform overhanging the passage, and inclining by a very gentle declivity to the very edge of the rock. Four enormous stones, which are placed upon the platform, and on the edge and extremity of it, have evidently been guided by art into that position, it being impossible that they could have rested there bad they been rolled down from the higher parts. The obvious reason for placing them in such a position has been, that on an alarm of danger they might be projected into the path below, which could be effected by the efforts of a very few men; and when done, the passage would be entirely obstructed, or at least rendered go difficult that it could be defended by a few men against any number of assailants. Some other large stones are placed on an eminence to the left, probably with a view to block up a hollow channel, by which an enemy might bave attempted to ascend. When the traveller reaches the top of the hill, a few feet below the rampart which crowns the whole, there appears an outward wall, approaching on the sides of the hill so near the upper rampart as to have only a trench of ten or twelve feet wide between them. This outward wall is in some places so low as to be almost level with the rock, though in other places it rises to the height of two or three feet; but even where lowest, it may be traced by a line of vitrified matter sticking fast to the rock all along, and nearly of the same breadth, which is about nine feet. The remains of this wall are strongly vitrified, excepting in one place on the north side, where, for about seventy yards, the rampart is formed only of dry stones and earth. At the east side, where the hill is more accessible, there is a prodigious mound of vitrified matter above forty feet in thickness. At the south-east corner, and adjoining to this immense mound, is an outwork, consisting of two semicircular vitrified walls, with a narrow pass, which appears to have been the principal entry to the fort, cut through in the middle.

The inner wall, surrounding the summit of the hill, encloses an oblong level area of about seventy-five yards long and thirty broad, rounded at each of the ends like the outward wall. It is of considerable height, and nearly of the same thickness with the outward one. It has some appearance of having been defended with four turrets or bastions; but the traces are so imperfect that Mr Tytlerdoes not lay much stress on his observations in this respect; a number of small tumuli of earth, with a stone in the centre, were more discernible. On the east side a portion of the internal space appears separated from the rest by two ranges of stones fixed strongly in the earth, and forming a rectangular parallelogram. “This separation,” says our author, “is immediately discernible by the eye, from this circumstance, that the whole of the enclosed summit has been most carefully cleared from stones, of which there is not one to be seen, unless those that form this division, and the single one in the middle of the circle of tumuli above mentioned. What has been the design of this separated space it is difficult to conjecture. It might perhaps have marked the residence of those of a higher rank, or served as a temple for the purposes of devotion.” At the east end of the large area on the summit is a well of about six feet in diameter, which has probably been sunk very deep in the rock, though now it is filled up with rubbish to within a yard of the top.

In the parish of Meigle, in the county of Perth, there is a hill called Ðarryhill, which seems to have been forti∙ fied with particular care. “Its summit,” says Dr Playfair, by whom it has been described, “was levelled into an area a hundred and eighty feet long and seventy-two broad. Around the area a mound of earth was raised from six to eight feet high and ten to twelve broad at topt On this mound a wall of freestone was built, without any cement whatever. The foundation of the wall was composed of rough granite, and still remains. It is of the same breadth with the summit of the mound, but the height of the wall cannot be known. Gordon’s estimate of it is very erroneous. Among the ruins there are several pieces of vitrified stone, but these vitrifications must have been accidental, as they are few and inconsiderable. Along the west and north borders of the area are barracks, or huts of dry stone, and sufficiently sheltered by the mound and wall; but no structures of this sort can be traced in the south part of die area. As the north and west sides of the hill are steep, and of difficult access, there was no need of an outer ditch in these quarters; but towards the south and east, where the hill gently slopes, there is a ditch ten feet broad and twelve to sixteen feet below the foundation of the wall. At the south-east extremity of the fort a narrow bridge was raised over the ditch, eighteen feet long and two broad, except towards each end, where the breadth was increased. It was composed of stones, laid together without much art, and vitrified above, below, and on both sides, so that the whole mass was firmly cemented. That an opening was left below, after the process was finished, is doubtful. On the upper part of the bridge a stratum of gravel was laid, to render the passage smooth and easy. This is the only part of the fort intentionally vitrified. A few yards distant from the ditch there is an outer wall, the foundation of which is about eight feet lower than the summit of the mound. The approach to the fort is from the north-east, along the verge of a precipice; and the entrance was secured by a bulwark of stone, the ruins of which are extant. There is no vestige of a well within the fort; but westward, between the basis of the mound and the precipice, there was a deep pond or lake, recently filled up by the tenants in that neighbourhood. About a quarter of a mile eastward, on the declivity of the hill, there are some remains of another oval fort, of less extent than the preceding, consisting[7:9:758] of a strong wall and ditch. Tradition says that there was a subterraneous communication between these forts, which is not improbable.”

In reference to this description of Dr Playfair, Sir George Mackenzie observes,^[5. Archaologia Scotica, vol. iv. p. 184. ] “On going to examine what Dr Playfair has called a bridge, I found that this considerable mass consisted of primitive rock stones vitrified. It had not the. slightest resemblance to a bridge, either in its form or apparent use.” He goes on to state that its position is in the bottom of the trench, between the summit and the outer rampart; and then observes,^[6. Archaologie Scotica, ibid. ] “The singularity of Barry Hill is in the vitrified matter being in the trench. If it shall afterwards be found that the whole extent is composed of melted stones, this circumstance also will be remarkable, as it will indicate an intended collection of vitrifiable stones. But if detached vitrified masses only shall be found, then their presence may be presumed to have been accidental."

Near Creich, in the county of Sutherland, a ridge projects into the Frith of Dornoch, terminating-in an abrupt precipitous hill. The ridge runs nearly east and west, and the top is of difficult access; whilst the summit, the outline of which is very irregular, is encircled by a rampart of loose stones. Within this there is another rampart of the same kind, which encloses the remains of a building constructed of stone and mortar. It is about thirty feet square, the walls being three feet thick, but not now more than four feet in height. There is a spring of water on the outside of the rampart, and at a short distance within it there is a well, which has been filled up. What renders this ruin remarkable is, that within the enclosure of the rampart, and at one end of it, there runs across the whole summit a mass of stones displaying abundantly the marks of fire; and the vitrification, according to Sir G. Mackenzie, is entirely confined to this part of the hill. The surface of the hill within this rampart is uneven and rocky; and that part of it which is crossed by the , vitrified mass is rather lower than the eastern portion.

Near the church of Amwoth, in the county of Kirkcudbright, there is a steep rocky hill about three hundred feet high, the summit of which has been fortified. “The top, which forms a level area thirty paces long and twenty broad,” says the Rev. Mr Gordon, by whom it has been described, “is nearly surrounded with an irregular ridge of loose stones, intermixed with vast quantities of vitrified matter. The stones, consisting of the common blue βchistus of the country, have been softened, twisted, and partly fused by the fire. These heaps of loose stones and vitrified matter are scattered irregularly over the top of the fort, and exhibit no appearance of having ever formed a continued wall. The vitrification is only partial and superficial, and seems to have been the accidental effect of large fires kindled on these high rocks, either for some domestic purpose, or for signals to alarm the country on the approach of an enemy. It was formerly believed that these vitrified forts were peculiar to that part of the island which is north of the Forth. But besides the one described above, there are two others in the country, and they all command a very extensive prospect of the sea.”

In the island of Bute, in the parish of Kingarth, there is a vitrified fort; and 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 Dun-βkeig, which commands the entrance of Loch Tarbert. On the same hill, ramparts have been constructed with dry stones, without any vitrification.

On the hill of Laws, which is situated near the village of Sturdymuir, a few miles north-east from Dundee, there is a vitrified fort. The area on the summit is 133 yards in length and 66 in breadth, and all round it are to be seen the vestiges of a broad rampart, and large masses of vitrified stones. 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 lime-kiln. The enclosed area is about 140 yards long and upwards of forty broad, and the walls in some parts of this fort have been laid bare, so as to appear at least ten feet high. There is no perfect description of the extent of the vitrification, but Mr Tytler says that marks of it are visible all round the summit. Dr Anderson describes it as appearing here and there in horizontal or nearly horizontal streaks. Dr Jamieson informs us that the stones are in courses, and banded together, and that they have been very unequally and irregularly affected by the fire, and many of them not at all. Seven or eigiit varieties of stone appear to have been employed. On this hill there are several cross walls, and the vestiges of outworks, which altogether present much that is interesting to the curious in such subjects.

It is impossible in this place to describe 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, who has laboured with great industry in attempting to solve the problem of their probable origin, in a paper which was read to the Society of Antiquaries of Scotland in 1831, informs us that he had discovered masses of vitrified matter at Elsness, in the island of Sanday, one of the Orkneys. 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 what geologists call an argillaceous schist. Their fusibility they derive chiefly from the feldspar, or rather the alkali, which they contain.

At Jedburgh, and we believe in other parts of Scotland besides those above mentioned, vitrified matter has been found, but only in small quantity, and not presenting any appearance of having formed part of a building.

Not long after these structures were discovered by Mr Williams, the notion that their vitrification was of volcanic origin was started, and soon became very prevalent. It was embraced by Mr Pennant, the eminent naturalist, who came to this conclusion after an examination of Craig-Phaidrick. A similar view was adopted by other individuals; and the appearance of the hill in question, as well as that of some others of these forts, is not ill calculated to favour this opinion. But as other ruins of the same kind came to be discovered, and an appearance of regular construction began to develop itself, another and a more rational hypothesis was advanced. In the year 1777, Mr Williams published a pamphlet, in which the validity of the volcanic theory was opposed. This author first assured himself, on the authority of Dr Black, the celebrated chemist, that many varieties of the rocks of Scotland were fusible by artificial means, and then advanced the theory that vitrification was artificially induced, as a cement for the consolidation of ramparts of loose stones. He supposed that they were constructed in the [7:9:759]following manner: Two parallel dikes of earth or sod being raised in the direction of the intended wall, with a space between them sufficient for its thickness, the fuel was put in and set on fire. The stone best adapted for this purpose, called the plum-pudding stone, is everywhere to be found in the neighbourhood. Stones of this description were laid on the fuel, and, when melted, were kept by the frame of earth from running off; and by repeating the operation, the wall was raised to a sufficient height. Amongst others who adopted the theory of Mr Williams, was Dr Anderson, who improved upon it by suggesting that a peculiar kind of vitrifiable ore was employed to promote the vitrification.

In a paper published in the year 1827, in the Transactions of the Royal Society of Edinburgh, another hypothesis was advanced by Lord Woodhouselee, who had some time before made an extensive survey of the vitrified forts. Mr Williams, probably from too partial an examination, had erroneously asserted that every stone composing a vitrified fort had been acted upon by the fire; but Lord Woodhouselee finding that the fact was not so, and that many parts of the walls showed no marks of vitrification, began to doubt the theory of Mr Williams. Whilst he agreed with him in thinking these structures artificial works, he differed from him in supposing that their vitrification was accidental. It was not, he said, in their construction, but in their demolition, that they were vitrified; and this may be supposed to have occurred from many circumstances. In the rude state in which Scotland existed at the early period to which the erection of these forts must be attributed, it is probable that their buildings, both for habitation and defence, would be frequently constructed of loose stones of an irregular shape, which, of themselves, could scarcely form a wall of any tolerable strength. Hence it became necessary to employ wood as well as stone in their construction. This kind of building, then, in our author’s opinion, was begun by raising a double row of palisades or strong stakes in the form of the intended structure, in the same way as in that ancient mode of building described by Palladio under the name of riempiuta a caffa, or coffer-work. These stakes were probably warped across by boughs of trees laid very closely together, so as to form two fences running parallel to each other at the distance of some feet, and so close as to confine all the materials, of whatever size, that were thrown in between them. Into this intermediate space, his lordship supposes, were thrown boughs of trees, earth and stones of all sizes, large or small as they could quarry or collect them. Very little care would be necessary in the disposition of these materials, as the outward fence would keep the mound in form. In this way it is easy to conceive that a very strong bulwark might be reared with great dispatch; which, joined to the natural advantage of a very inaccessible situation, and that improved by artful contrivances for increasing, the difficulty of access, would form a structure capable of answering every purpose of security or defence. The most formidable attack against such a building would be fire, which would no doubt be always attempted, and often with success, by an enemy who undertook the siege. If the besiegers prevailed in gaining an approach to the ramparts, and, surrounding,the external wall, set fire to it in several places, the conflagration must speedily have become universal, and the effect may be easily imagined. If there happened to be any wind at the time to increase the heat, the stony parts could not fail to come into fusion; and as the wood burnt away, sinking by their own weight into a solid mass, there would remain a wreck of vitrified matter tracking the spot where the ancient rampart had stood; irregular, and of unequal height, from the fortuitous and unequal distribution of the stony materials of which it had been composed.

The fifth and last theory is, that the vitrification of these forts was the result of beacon-fires. This opinion first obtained supporters amongst the contributors to Sir John Sinclair’s Statistical Account of Scotland. It was afterwards advocated by Sir George Mackenzie in the article previously referred to; and latterly by Dr Hibbert, who has published several ingenious papers on the subject in the Arch<zologia Scotica. Such are the various hypotheses which have been advanced explanatory of the singular phenomena of vitrified forts.· To present any thing like a complete view of the arguments which have been produced in support of each, would occupy more space than can here be allotted to the subject; an abstract, therefore, of those which are most striking can only be given. In general those who have considered the subject at all are divided into two classes; namely, those who support the theory of Mr Williams, and those who advocate the beacon-fire theory. Amongst the most eminent of the former class is Dr Macculloch, who published a memoir upon the subject in the Transactions of the Geological Society of London, and also treated of it in his work on the Highlands and Western Isles of Scotland.

But, first, with respect to the beacon theory. That at a very early period of Scottish history mountain fires were lighted for the purpose of alarming the country when an enemy appeared upon the coast, is an undoubted historical fact. The primary assumption is therefore undeniable. With respect to their origin, many of those who support the hypothesis that the vitrification of these forts is the result of beacon-fires, have offered conjectures as to the date of their erection. Upon this subject Dr Hibbert observes,^[7. Archaologia Sntica, vol. iv. p. i70. ] “The coasts of Scotland began to be annoyed by the predatory visits of the Vikingr (Sea-kings) about the end of the eighth century; but it was not probably until the Scots had obtained a complete ascendancy over the Picts, by which both were united under one government, that systems of beacons were formed to provide against the sudden descent of the Scandinavians, who invaded them from the Danish or Norwegian shores, or from countries which they subsequently colonized, namely, from Shetland, Orkney, Caithness, Sutherland, the Hebrides, Ireland, or the Isle of Man. The Murray Frith, as we learn from ancient Sagas, was one of the most convenient landing places for the Northmen; and hence we must look to this locality for the greatest proportion of vitrified sites. The number of such as have been traced within sight of each other, in a direction east to west from Banff to Dingwall, and in a direction north to south from Cromarty to Fort Augustus, may be estimated at twenty; but it is probable that their actual amount will be eventually found to be much more. Two vitrified eminences appear near Huntly, connected apparently with the line of coast extending from Kinnaird’s Head to the mouth of the Dee. More south, a chain of vitrified sites, nine or ten in number, appears to have conveyed signals from the line of coast which stretches from Kincardine to the Tay, being prolonged from Stonehaven or Dundee to the neighbourhood of Dunkeld or Crieff. On the west coast, again, we find similar vitrified sites at Bute, Cantire, Isla, Loch Etive, Loch Sunart, Fort William, or at Arisaig. The number which subsists on the west yet remains to be ascertained; about twelve have been enumerated. Lastly, at Galloway, three occur, [7:9:760]apparently as signals against the marauding colonists of Ireland.

“But it must be kept in view, that it is highly improbable that the original intent of the whole of these vitrified sites was that of affording convenient localities for beacon-fires. There is no necessity whatever, coeteris paribus, that signal lights, merely giving notice of the approach of an enemy from the sea, should be situated on fortified stations. It is not improbable, therefore, that the rude ramparts themselves might, at a still more remote period, have been erected by the oldest inhabitants of Albyn, namely, by the Caledonians and Picts; and hence their occasional or very partial vitrification would merely indicate the later use to which the eminences upon which they were situated had been applied, when the Scots, who succeeded to far earlier inhabitants, were called upon to repel new invaders from the sea.”

Dr Hibbert goes on to remark, that after the Norsemen had acquired a permanent settlement in Scotland, and also in other places, they themselves became liable to sudden piratical descents from their own countrymen; to guard against which they instituted, in every country where their arms prevailed, still more perfect systems of beacon-fires, the wardenship of which was enforced by the most rigorous laws. This we are informed of by ancient Sagas, and edicts on the subject are found in many early codes of the north of Europe. From two ancient writers, Olaus Magnus and Snorro, passages are quoted, which go to prove that large trees were felled, formed into piles upon mountain tops, and then set fire to, for the purpose of giving intelligence to the country of a hostile invasion. These, however, obviously apply to countries upon the Norwegian coast in particular; but they may be extended to those portions of Scotland which were under the domination of the Norsemen.

The same writer further observes, that vitrification may in some cases have resulted from fires having been lighted in these forts during the observance of religious and other festivals. The custom of kindling immense fires on occasions of feasting was certainly common in ancient times; indeed, the custom of the Baaltein, or festival in honour of Baal, is observed in some districts even at the present time. He also supposes that many of the sites where vitrified remains occur were places of rendezvous for tribes or clans, upon public occasions of peace or warfare; and also that the ramparts afforded a shelter for cattle as well as for human inhabitants. Dr Hibbert sums up his evidence in support of the beacon theory by giving a list of the ancient forests of Scotland, from which it appears that the country was formerly in a densely wooded state, and hence afforded ample materials for kindling beaconfires upon the grandest scale, and celebrating the rites of Baal, or any other object of worship, in a manner sufficiently flagrant to propitiate the favour of the most exorbitant fire-loving god of antiquity.

In the Transactions of the Society of Antiquaries of Scotland, vol. iv. are various papers relative to vitrified sites, which were read to the society by Dr Hibbert in the year 1831. These contain several communications from Sir George Mackenzie, Mr George Anderson, and others, in which the main principle, that these forts were beacon stations, is supported by an attempt to establish the fact that the hills on which they are found form a regular chain of signal stations which command each other. By this arrangement a fire kindled on one of them could be seen by those contiguous, and thus intelligence communicated throughout the whole line, on whatever part of the coast the enemy might make their appearance. This hypothesis was advanced by Sir George Mackenzie, in his article on vitrified forts in the Edinburgh Encyclopaedia, where he also lays much stress upon the appearances exhibited by the hill of Dun Creich, in which, as formerly mentioned, only the singular wall which runs from one side to the other of the rampart shows marks of vitrification. The reason assigned for traces of fire being only partially visible in this and in all the other forts is, that the combustible matter was always placed so as to be sheltered from the wind. “To be satisfied,” he observes, “whether the signal-fires should be kindled on or beside a heap of stones, we have only to imagine a gale of wind to have arisen when a fire was kindled on the bare ground. The fuel would be blown about and dispersed, to the great annoyance of those who attended. The plan for obviating the inconvenience thus occasioned, which would occur most naturally and readily, would be to raise a heap of stones on either side, of which the fuel might be placed to windward.”

Such are the leading arguments produced in support of their doctrine by the advocates of the beacon theory. The most distinguished advocate of Mr Williams’ views is Dr Macculloch, to whose works on the Highlands and Western Isles we have already referred. The doctor observes, with reference to the partial vitrification of the walls, that had the walls been the enclosures of beaconfires, every stone from the summit to the base must have felt their effects alike. But the great variety found in the forms and sizes of these works, their obviously military and defensible character, and the enormous size of some of them, as for instance that at Noath, seems, in his opinion, to render the notion of their having been signal-stations scarcely worth refuting. “At Amwòth, in Galloway,” he says, “the hill has been scarped by art, so as to form a deep ditch close to the foot of the wall. Nothing of this kind could have been required for a beacon; and it is further remarkable, that the transverse wall at Dun MacSniochain is a common expedient for defence in the ancient British works that occupy peninsulas of promontories; as at Castle Trereen, Zenor, and Tintage), in Cornwall. The advanced covered-ways of Noath and Dunadeer, and the causeway of the former, would be equally unnecessary on such a supposition; nor, at Noath, could any possible purpose of a beacon have demanded or justified such an enormous work, whether we consider the area enclosed, or the height and thickness of the walls.

“To imagine an area of 2700 square yards covered with burning wood, and to conceive a wall that would have required the labour of many hundred men for weeks, built for no other purpose than to enclose what did not want enclosing, are dreams not deserving a serious examination If a chemical argument were wanted in addition to these it would be found in the fact, that though all this wood a forest in itself, were collected and lighted, when a square yard would have served the purpose as well as two 01 three thousand, it would not vitrify its enclosure in thí manner in which these walls are vitrified; as the currenl of air from without would, by cooling the external part, impede its action on the outside, where the fusion is a! complete as within. It has been asserted that these vitrified forts actually did communicate in chains, or in connection, throughout the country. Nothing but a similar ignorance respecting these works and their places could have led to such an assertion; it is not the fact; in many instances it is physically, geographically, and optically impossible; and the mere supposition involves equal ignorance of the political state of Scotland in ancient times,orelse hypothesis respecting its union under one organized government, which is purely gratuitous. Many of then indeed are placed in situations so low, or so entangled among hills, as to preclude all communication of this nature[7:9:761]; as is the case in Isla, in Morven, in Ardnamurchan, in Galloway, and apparently along the course of the Bogie in Aberdeenshire.”

Dr Macculloch goes on to observe, that the appearances of the burned and vitrified substances appeared to him to prove that a long-continued and intense heat had been applied, neither of which effects could have resulted from the burning down of a wall formed of stone and wood, as Lord Woodhouselee supposed was the case. The plan of constructing a species of furnace by means of earthen mounds, into which stones and fire were introduced till the structure was finished, not only, according to our author, answers all the conditions, and, among the rest, that of vitrifying the materials below more perfectly than the upper ones, but is confirmed as to its probability and efficacy by a practice in use in some parts of India. We are informed by a French engineer, that in that part of Asia houses of clay are burned into a solid brick, in this very manner and at this day, in order to prevent the effects of inundations. Dr Macculloch further observes, that the art seems to have been practised in England, though with a different end in view. Some years ago a house was demolished in Shropshire, part of which, of unknown antiquity, was covered with an entire crust of glass, apparently for the purpose of protecting it from the effects of the weather.

With respect to the antiquity of these forts, little can be advanced that is satisfactory. Our author offers a speculation, that if they were built by one people, in the widely-separated districts where they are found, they ought to belong to a time prior to the division of Scotland into a Pictish or Caledonian, and a Scottish or a Celtic and Norwegian dominion. Thus they should be referred to the aboriginal Celts, or first settlers of Scotland; that people whom the Pictish invaders found, and on whose defeat they settled themselves in the conquered country. The same writer concludes his observations by expressing a hope “that some future traveller in the East will find further reasons to prove that they are among the earliest military works of our oriental Celtic ancestors.”

Such are the arguments brought forward by each of the parties in support of their theories as to the origin and design of vitrified forts. It must be confessed that a case perfectly satisfactory and free from doubt is made out by neither of them, although the balance of probability seems in favour of the opinion that they were regular military works, vitrified on purpose, for the sake of strengthening the walls at the time when cement was unknown. In support of this view of the case, we shall offer a few remarks.

The main question is, were these forts intentionally vitrified, for the purpose of cementing the walls together? or was the vitrification an accidental result of beacon-fires being lighted up within their enclosures? It would certainly be injudicious to advocate either theory exclusively. For if, on the one hand, we maintain that they were intended for places of strength, some of them are evidently too small, and would have been utterly useless for that purpose; and if, on the other hand, it be asserted that they were signal-stations accidentally vitrified by signal-fires being lighted there, then the size and elaborate construction of some of them indicate their adaptation to something of far more importance. Sir George Mackenzie observes: “We allow, that while these hills were chosen for signal-stations, they were also used as places of defence. And indeed it would have been strange if posts of so much importance had been left without the means of resistance. All have agreed that they were places of more or less strength, though perhaps such lofty and exposed situations were not well chosen for protracted warfare. Had they been merely places of retreat, an invading enemy would certainly overlook them, as he could overrun and pillage the country without the possibility of his being annoyed from them; or if there was any risk of his progress being interrupted, the situation of the hills would render it easy for a small party to coop up the garrison. But as an enemy would always endeavour to approach unseen, and to prevent the country from being alarmed, these stations would undoubtedly be objects of attack; and hence we should be warranted in supposing that they were to a certain extent fortified, even were the appearance of ramparts less unequivocal.” Now, as Sir George advocates th⅛ opinion that vitrification was an accidental result of fires being kindled in these forts, of what possible use could they be as strongholds? For if these watch-towers were lit when the enemy appeared, then of course those within would be compelled to evacuate them, as no living thing could have breathed within some hundred feet of the place where such immense conflagrations took place. It seems, therefore, a very improbable circumstance, that men, even allowing that they were sunk in the lowest barbarism, would laboriously construct and fortify a place which they must have been aware it would be necessary to abandon at the very time when they were most needed.

With regard to the vitrification on the hill called the Top of Noth, the same writer observes: “The vitrification is only in the inside, which is a very satisfactory confirmation of the idea that it has been produced by signal-fires. Had the outside of the rampart on Top of Noth^[8. Other individuals, who have examined the above fort, inform us that it is vitrified on the outside as much as on the inside. ] been vitrified, we might have been warranted in concluding that fire had been used to strengthen it. Had the inside been vitrified with this view, it is impossible to conceive that no attempt was made to cement the outside also; since in every structure for defence, however rude, we find the strongest, and not, as in this instance, the weakest, part opposed to the approach of an enemy.” This reasoning seems by no means conclusive. Vitrification was had recourse to, not because the vitrified matter thus formed was of a stronger nature than the materials which it bound together, but simply because it did bind or cement them, so as to form one solid fabric. Now this might be accomplished either on the one side or the other, without making any very great difference as to strength. It is, however, very problematical if those who constructed these fabrics had any thing of this kind in view when they erected them; and as vitrification occurs on the outside of other forts, little weight can be attached to this argument. In those forts which were vitrified only on the inside, it seems probable, that from the nature of the hill where they stood, it was found impracticable to accomplish it on the outside. Various other circumstances besides the nature of the ground may have occurred to determine both the extent of the vitrification and the choice of the parts where it was to be effected.

Sir George Mackenzie further observes, with respect to the situation of the forts: “We do not remember an instance in which there is not much higher ground immediately contiguous to the hills on which the vitrifications are found.”^[9. There is no high ground contiguous to Dunadeer or to Noth. ] Now, granting that the situation of every one of them was a commanding one, and that the whole were connected together like links in a chain, so that a fire on any given hill could readily communicate intelligence to the others, is it not probable that those who [7:9:762] erected the signal-stations would have chosen the highest accessible elevations, such as towered above all the neighbouring heights, and commanded the widest range of country? By this means the end would not only have been more perfectly effected, but the number of signalstations would have been lessened by one half, or perhaps more; and to suppose that the aboriginal inhabitants of Scotland would have overlooked this obvious fact, is to attribute to them a degree of ignorance below that of the most savage tribes which the enterprise of modern times has discovered. An erroneous notion seems to prevail as to the extent of fire requisite to convey intelligence of the approach of a foe. But it was not necessary to keep up the combustion for any length of time. Supposing that these were signal-stations, a temporary blaze would communicate all the intelligence that was required, and just as much as could have been conveyed, although the fire had been continued for a considerable period of time. The more that the advocates of the beacon theory insist on their being a regular chain of forts, the less necessity there is for supposing that the fires were so large, and continued for such a length of time, as to vitrify rocks. If it be urged, as it has been, that vitrification was produced, not by the intensity of the fire atone time, but resulted from repeated applications of it, still this could only apply to vitrification upon the surface; for, allowing that on any given occasion, when the beacon was lighted, the heat was sufficient to vitrify the rocks one inch inwards, upon the next occasion when it became necessary to repeat the signal in the same place, it is not to be supposed that it would vitrify it another inch farther inwards. This supposition would involve the absurdity that the fires lighted were on every successive occasion stronger and stronger, a circumstance which was not likely to occur. Besides, considering the height to which it was necessary to convey the combustibles, it is probable that, when the fires were once found to answer the purpose, and the people knew that they would do so again, they would become less rather than greater. Hence we may conclude, that in every case where the vitrification penetrates to some depth inwards, it resulted from an intense continuous heat, kept up for a long period, not from a series of petty fires. Where the chain of communication was regular, there was, as we have said, no necessity for such stupendous piles of burning wood as were requisite for vitrifying some feet of a wall; the combustion of a few trees would have accomplished the end as well as if the blaze of Aetna had irradiated the summits of the hills. But though not an absolute necessity, there was a degree of propriety which could scarcely have been overlooked in placing them within sight of each other, as has been asserted by the advocates of the beacon theory. Dr Macculloch, however, as we have seen, has denied that this is the case; but his statement must be taken with caution, for a great many sites probably remain undiscovered. However, the main question will not be affected by the decision of this point. The more numerous the forts were, the less use was there for immense conflagrations, and hence the probability is lessened that they were so extensive as to fuse masses of rock.

The following is a quotation from one of the papers of Dr Hibbert: “None of these vitrified forts exhibit, as from many writers we should be erroneously led to suppose, any regular masonry in their structure. Unhewn fragments of stones, and water-worn boulders, sometimes mingled with smaller gravel, appear in a quantity almost exceeding belief, following the contour of the summit of a mountain, or, as in the instance of a fort which is situated in the Kyles of Bute, following the contour of a small holm or islet, elevated a few yards only above the level of the sea;

; and in cases where, owing to the more exposed nature of the ground, a stronger defence is demanded, a double or- ’ even treble rampart of the same rude materials is added.! The vitrification which characterizes these forts is, in some few of them, displayed to an extent that is perfectly i astonishing; while in other instances it is with difficulty ' to be detected.”

At an early period, the want of proper tools for either quarrying stones, or hewing them into symmetrical forms, would compel builders to seize upon such masses as pre-; sented themselves, whether round, oval, or of any other ι shape. Now, in order to form a level bed upon which ∣ these might repose with any degree of security, they: would naturally have recourse to gravel and debris of some kind, for at this period they seem to have been ignorant of cement. It cannot be denied that a very unstable erection would result from this method of building; for the walls would not only be easily demolished by a hostile force, but rain, which falls in large quantities in mountainous regions, by percolating through the fissures, would soon have washed away the unconsolidated mass. But, granting that signal-fires had accidentally vitrified the walls in one instance, is it not to be presumed that the idea of cementing the walls of their strongholds by means of fire would suggest itself to those who observed the fact? This is an extremely probable circumstance; and it is strongly corroborated by the fact mentioned by Dr Macculloch, and many others who have examined these ruins, that stones of an easily fusible nature were brought from some distance, whilst those composing the mountain upon which they stood were neglected. This was certainly done intentionally; but of what use was it to build of such materials the walls of what may be called a furnace? Obviously of none whatever. On the contrary, there was an evident disadvantage. For as in every fire-place a plentiful supply of air is necessary to support combustion, it is clear, that as soon as the rocks began to melt, the interstices would have been filled up, and the combustion immediately checked. It was the object of the builders to construct their fire-places of unfusible rocks, and it was also necessary to leave numerous openings for the free admission of air; but it would appear that no indication of any such thing is to be traced in these ruins, a circumstance which strongly supports the truth of the hypothesis that they were regular forts, not beacon-stations. The presence of wells or tanks for water in some of these forts, of double and of triple walls and causeways leading up to them in others, besides many other circumstances which might be adduced, all go to prove the same view.

ìn a word, the probability is, that the natives having observed the effects of fire upon some stones of ramparts which enclosed beacon-fires, acquired the idea of consolidating their places of strength by the same means, at a time when the use of cement was unknown. Those parts of vitrified forts which show that mortar was used in their construction must, according to all accounts, be referred to a later date than that of the vitrified portions of these