were often opened to be as often abandoned, shows that they must have occasionally fallen somewhat below even this low line. Latterly, at least, it was rather the deficient quality of the coal that militated against the speculation, than any deficiency in the quantity found. It burned freely, and threw out a powerful flame; but it was accompanied by a peculiar odour, that seemed to tell rather of the vegetable of which it had been originally composed than of the mineral into which it had been converted, and then sunk into a white light ash, which every breath of air sent floating over carpets and furniture. And so, when brought into competition, in our northern ports, with the coal of the Mid-Lothian and English fields, it failed to take the market. The speculation of Williams was singularly unlucky. He became lessee of the entire field about the year 1764, and wrought it for nearly five years. There occurs near the centre of the main seam a band of pyritiferous concretions, which here, as elsewhere, have the quality of taking fire spontaneously when exposed in heaps to air and moisture, and which his miners had not been sufficiently careful in excluding from the coal. A cargo which he had shipped from Portsoy, in Banffshire, took fire in this way, in consequence, it has been said, of the vessel springing a leak; and such was the alarm excited among his customers, that they declined dealing with him any longer for a commodity so dangerous. And so, after an ineffectual struggle, he had to relinquish his lease.

LONDON MUSEUM OF ECONOMIC GEOLOGY.

In the Museum of Economic Geology now in the course of forming in London, there are specimens exhibited of not only the various rude materials of art furnished by the mine and the quarry, but also of what these can be converted into by the chemist and the mechanic. Not only does it

show the gifts of the mineral kingdom to man, but the uses also to which man has applied them. The rough and unpromising block of marble stands side by side with the exquisitely polished and delicately-sculptured vase. The bracelet of glittering steel, scarcely of less value than if wrought in gold, ranges in striking contrast with the earthy, umbry nodule of clay-ironstone. There are series of specimens, too, illustrative of the various changes which an earth or metal assumes in its progress through the workshop or the laboratory. Here, for instance, is the ironstone nodule, there the roasted ore,-yonder the fused mass; the wrought bar succeeds; then comes the rudely-blocked ornament or implement; and, last of all, the exquisitely finished piece of work, as we find it in the cutler's warehouse or the jeweller's shop.

I am not aware whether the museum also exhibits its sets of specimens illustrative of substances elaborated, not by man, but by nature herself, and elaborated, if one may so speak, on the principle of serial processes and succeeding stages. The arrangement in many cases would have to proceed, no doubt, on a basis of hypothesis; but the cases would also be many in which the hypothesis would at least not seem a forced one. It was suggested to me on the Brora coal-field, that the process through which nature makes coal might be strikingly illustrated in this style. One might almost venture to begin one's serial collection with a well-selected piece of fresh peat, containing its fragments of wood, its few blackened reeds, its fern-stalks, and its club-mosses. Another specimen of more solid and homogeneous structure, and darker hue, cut from the bottom of some deep morass, might be placed second in the series. Then might come a first specimen of Bovey coal, taken from under its eight or ten feet of Tertiary clay, a specimen of light and friable texture, and that exhibited more of its original vegetable qualities than of its

acquired mineral ones. A second specimen, brought from a deeper bed of the same deposit, might be chosen by the darker brown of its colour, and its nearer approximation to the structure of pit-coal. The Oolitic coal of the Brora or Yorkshire field might furnish at least two specimens more. And thus the collector might pass on, by easy gradations, to the true Coal Measures, and down through these to the deeply-seated anthracite of Ireland, or the still more deeply-seated anthracite of America,-not altogether so assured of his arrangement, perhaps, as in dealing with the processes of the laboratory or the workshop, but at least tolerably sure that both chemists and naturalists would find fewer reasons to challenge than to confirm it.

BRORA PEAT-MOSSES OF THE OOLITE.

THE Brora field, so various in its deposits, must have existed in many various states,-now covered by salt water, now by fresh,-now underlying some sluggish estuary,now presenting, perchance, a superaqueous surface, darkened by accumulations of vegetable matter,-and now, again, let down into the green depths of the sea. To realize such a change as the last, one has but to cross the Moray Firth at this point to the opposite land, and there see a peatmoss covered, during stream tides, by from two to three fathoms of water, and partially overlaid by a stratum of seasand, charged with its characteristic shells. It is a small coal-bed, kneaded out and laid by, though still in its state of extremest unripeness,—a coal-bed in the raw material; and there are not a few such on the coasts of both Great Britain and Ireland. Professor Fleming's description of the submerged forests of the Firths of Forth and Tay must be familiar to many of my readers. They must have heard, too, through the far-known Principles of Lyell, of the

submerged forests of Lancashire. 'In passing over Black Sod Bay, in a clear, calm morning,' says a late tourist in Erris and Tyrawly, 'I could see, fathoms down, the roots of trees that seemed of the same sort as are every day dug out of our bogs.' Now, we do not know that the Oolite had properly its peat-mosses. The climate, though its pines had their well-marked annual rings, seems, judging from its other productions, to have been warmer than those in which peat now accumulates; but there can be no doubt that both it and the true Coal Measures must have had their vast accumulations of vegetable matter formed, in many instances, on the spot on which the vegetable matter grew; and no one surely need ask a better definition of a peat-moss. A peatmoss, in the present state of things, is simply an accumulation of vegetable matter formed on the spot on which it grew. These, as I have said, we frequently find let down on our coast far beneath the sea level, and covered up by marine deposits; and the fact furnishes a first and important step in the proposed serial arrangement of coal in the forming. May I not further add, that Professor Johnston of Durham, so well known in the field of geological chemistry, regards all our coal-seams, whether of the Carboniferous period or of the Oolitic, as mere beds of ancient peat, mineralized in the laboratory of nature?

QUARRY OF BRAAMBURY UPPER OOLITE, SUTHERLAND.

ON entering the quarry hollowed on the southern eminence, one is first struck by the character of the broken masses of stone that lie scattered over the excavations. The rubbish abounds in what seem fragments of a very exquisite sculpture. The shells and lignites, which it contains in vast numbers, exist as mere impressions in the white sandstone, and look as if fresh from the chisel of a

R

Thom or Forrest. But even these masters of their art would confess themselves outdone here in beauty of finish. Their best works don't stand the microscope; whereas the carvings of the Upper Oolite here, though in sandstone, mightily improve under it. The cast of a broken fragment of wood at present before me shows not only the markings of the annual rings, but also the microscopic striæ of the vegetable fibre, a niceness of impression impossible in any sandstone that had not what the sandstones of this quarry have,—a large mixture of calcareous cement. I remember that, on my first introduction to the excavations of Braambury, for such is the name of the quarry,—the vast amount of what seemed broken sculpture in the rubbish reminded me of some of Tennant's singularly happy descriptions in his Dinging down o' the Cathedral. They seemed memorials of a time when, to the signal detriment of ecclesiastical architecture in Scotland, and all the good solid religion that springs out of sandstone,—

Whan in ilk kirk the angry folk

Carv't wark, an arch, an pillar broke.'

I had not a few other recollections of the quarry of Braambury. Nothing can be more interesting to the geologist than its fossils, and nothing more annoying at times to the workman. Occurring often in the wrought stone, they occasion sad gaps and deplorable breaches, where the plane should be smooth or the moulding sharp. I remember laying open on one occasion a beautiful cast that had once been a belemnite, but that had become a mere cavity in which a belemnite might be moulded,-for even this solid fossil, that so doggedly preserves its substance in most other deposits, is absorbed by the sandstone of Braambury. And