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Loch Etive and The Sons of Uisnach


THE first observer of vitrified forts was Mr. John Williams, who described them in a small book entitled "On Highland Ruins," published in Edinburgh in 1877. It contains the following letter:-

Letter from DR. JOSEPH BLACK, Professor of Chymistry in the University of Edinburgh.

"SIR,—I am much obliged to you for the sight of your letters concerning the vitrified fortresses in the 'North. I had got formerly from some of my friends, some accounts of extraordinary vitrified walls which they had seen in the Highlands; and Mr. James Wyatt, who spent some time in surveying a part of that country, communicated a number of particular observations which he had made upon one of these ruins; but we were not enabled to judge with any certainty, for what purposes, or in what manner, these hitherto unheard-of buildings had been erected. It is very probable that they were executed in some such manner as you have imagined. There are, in most parts of Scotland, different kinds of stone, which can, without much difficulty, be melted or softened by fire, to such a degree, as to make them cohere together. Such is the grey stone, called whin-stone, which, for some time past, has been carried to London to pave the streets. Such also is the granite, or moor-stone, which is applied to the same use, and pieces of which are plainly visible in some specimens of these vitrified walls, which I received from my friends. There are also many lime-stones, which, in consequence of their containing certain proportions of sand and clay, are very fusible: and there is no doubt that sand-stone and pudden-stone when they happen to contain certain proportions of iron mixed with the sand and gravel of which they are composed, must have the same quality. A pudden-stone composed of pieces of granite must necessarily have it.

"There is abundance of one or other of these kinds of stone in many parts of Scotland; and as the whole country was anciently a forest, and the greater part of it overgrown with wood, it is easy to understand how those who erected these works, got the materials necessary for their purposes.—I am, SIR, your obedient humble servant.


"Edinburgh, April 18, 1877.
"To Mr. John Williams."

From Remarks on the Construction of Vitrified Forts, by JOHN HONEYMAN, F.R.I.B.A. (Read at a meeting of the Archcological Society held at Glasgow on 10th February, 1868.)

"The conclusion to which the phenomena exhibited at Dunskeig pointed seemed to me to be this—that the walls were constructed of loose materials, bound together into a solid mass by being grouted with a liquid vitreous 'cement, composed chiefly of greenstone and other easily fused materials, and that the process was effected on the wall, not on either side of it. In this way it would be as easy to construct a wall twelve feet thick as two, and as easy to carry it along the verge of a precipice as on a plain. But, it may be asked, if the agglutination is chiefly effected in this way, how is it that we find so large a portion of the remains bearing the evidence of the action of intense heat ? The reason, I think, is obvious. The material could not have been melted at all without the action of intense heat on whatever enclosed the fire, and these enclosures must necessarily have been very numerous. It would, with our present amount of information on the subject; be obviously absurd to dogmatize as to the exact modus operandi, but I shall suggest a possible method. Suppose that first a course of loose stones was laid all round the enclosure the width of the proposed wall, across this a series of furnaces about eighteen inches wide and two feet high were formed, closed at each end, and separated by partitions composed chiefly of trap, the ends would form the outside and inside faces of the wall, and would be provided with holes for the passage of air through the furnace. The whole was then covered over with stones (to a considerable extent trap) and probably turf and sea-weed were added. In such a furnace —the means of producing a blast being satisfactory — an intense heat would be produced, and the result would be that the partitions and top would be fused." (Transactions of the Glasgow Archaeological Society. Part i., vol. ii.)

Mr. Honeyman makes the following addition to his paper:—

"Having extended my observation much since the above was written, I am able to add that the vitrifaction is generally less perfect towards the outside than in the centre of the wall, that in some forts which I have examined, the vitrified mass rests upon rough building which has never been subjected to great heat, and that in these cases the centre of the wall is vitrified to a greater depth than either of the sides. It seems evident therefore that the vitrifaction was effected from the top of the wall, not from the sides. In every wall I have examined there is abundant evidence that the cementing material has run dozen among the loose stones, and the same appearances prove that the dry building above referred to occupies still its original position under the vitrified mass. In the interstices among the unvitrified stones, drops and small streams from above still remain as they cooled.

1879. J. H.

It is, however, true that some of the loose stones have been exposed to great heat. The fort existing in Bohemia has been remarked to have had alternate layers of wood and stone.

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