The top of the Scuir, more especially towards its eastern termination, resembles that of some vast mole not yet levelled over by the workmen; the pavement has not yet been laid down, and there are deep gaps in the masonry, that run transversely, from side to side, still to fill up. Along one of these ditch-like gaps, which serves to insulate the eastern and highest portion of the Scuir from all its other portions, we find fragments of a rude wall of uncemented stones, the remains of an ancient hill-fort; which, with its natural rampart of rock on three of its four sides, more than a hundred yards in sheer descent, and with its deep ditch and rude wall on the fourth, must have formed one of the most inaccessible in the kingdom. The masses of pitchstone a-top, though so intensely black within, are weathered on the surface into almost a pure white; and we found lying detached among them, fragments of common amygdaloid and basalt, and minute slaty pieces of chalcedony that had formed apparently in fissures of the trap. We would have scrutinized more narrowly at the time had we expected to find anything more rare; but I did not know until full four months after, that aught more rare was to be found. Had we examined somewhat more carefully, we might possibly have done what Mr. Woronzow Greig did on the Scuir about eighteen years previous,--picked up on it a piece of _bona fide_ Scotch pumice. This gentleman, well known through his exertions in statistical science, and for his love of science in general, and whose tastes and acquirements are not unworthy the son of Mrs. Somerville, has kindly informed me by letter regarding his curious discovery. "I visited the island of Eigg," he says, "in 1825 or 1826, for the purpose of shooting, and remained in it several days; and as there was a great scarcity of game, I amused myself in my wanderings by looking about for natural curiosities. I knew little about Geology at the time, but, collecting whatever struck my eye as uncommon, I picked up from the sides of the Scuir, among various other things, a bit of fossil wood, and, nearly at the summit of the eminence, a piece of pumice of a deep brownish-black color, and very porous, the pores being large and round, and the substance which divided them of a uniform thickness. This last specimen I gave to Mr. Lyell, who said that it could not originally have belonged to Eigg, though it might possibly have been washed there by the sea,--a suggestion, however, with which its place on the top of the Scuir seems ill to accord. I may add, that I have since procured a larger specimen from the same place." This seems a curious fact, when we take into account the identity, in their mineral components, of the pumice and obsidian of the recent volcanoes; and that pitchstone, the obsidian of the trap-rocks, is resolvable into a pumice by the art of the chemist. If pumice was to be found anywhere in Scotland, we might _a priori_ expect to find it in connection with by far the largest mass of pitchstone in the kingdom. It is just possible, however, that Mr. Greig's two specimens may not date farther back, in at least their existing state, than the days of the hill-fort. Powerful fires would have been required to render the exposed summit of the Scuir at all comfortable; there is a deep peat-moss in its immediate neighborhood, that would have furnished the necessary fuel; the wind must have been sufficiently high on the summit to fan the embers into an intense white heat; and if it was heat but half as intense as that which was employed in fusing into one mass the thick vitrified ramparts of Craig Phadrig and Knock Farril, on the east coast, it could scarce have failed to anticipate the experiment of the Hon. Mr. Knox, of Dublin, by converting some of the numerous pitchstone fragments that lie scattered about, "into a light substance in every respect resembling pumice."