make moulds for casting sheet lead and other articles.* Sand fit for all these purposes, is found, according to Dr. Rutty, in various parts of the county of Dublin.+ A kind of sand composed chiefly of crystals, which is used for making scytheboards, greatly superior to those brought from England, is found on the shore of Lough Graney, in Clare. It is in such request among the country people, that they come for it upwards of twenty miles. Sand of the same quality is procured also from Lough Coutra, on the estate of Pendergast Smyth, Esq.‡

Silicious sand may be obtained in great abundance on Murkish Mountain in Donegal, which is situated within four miles of two deep and safe harbours, Sheephaven and Dunfanaghy. For some time past it has been sent to the Belfast glass manufactory, where it is substituted for that which used to be imported from England. It is supplied at the bay of Ards for two guineas per ton.§

STONES.

Among the productions of Ireland which may be classed under this head, none seem to have a greater claim to attention than that of basaltes, not on account of any useful purpose to which it is applied; but because nature presents it under the most awful forms, being sometimes piled up in immense structures of stupendous height and extent, where columns of it are arranged in various directions, and with as much regularity as if they had been deposited by the hand of man. It deserves considerable notice also on account of the dispute to which it has given rise between two classes of philosophers, the Plutonians and the Neptunians, the former of whom assert, that it is indebted for its origin to subterranean fire, while the latter maintain that it is the result of deposition, and consequently the production of water. Both these opinions have been supported by very ingenious arguments; and though able men have ranged themselves as partisans on each side, and endeavoured to solve the question, it does not appear to have been determined in a satisfactory manner. The basaltic district in Ireland occupies a range of coast stretched out from the estuary of Carrickfergus on the one hand, to Lough Foyle on the other, and extends inland to the southern shores of Lough Neagh. Throughout the whole of this

* Sand was formerly an object of commerce, and large quantities of it were sold by the Egyptians to the Romans for the use of their Athlete or wrestlers, who rubbed it over their bodies. It was sent to Rome, sometimes by ship loads; and Suetonius relates, that in the time of Nero, the people expressed the utmost indignation on seeing a vessel arrive from Alexandria entirely laden with the sand of the Nile, for the use of the wrestlers belonging to the imperial court, at a time when the city was reduced to a state of great distress for the want of corn. But this use of the sand of the Nile is much older; for we are informed by Pliny, lib. xxxv. cap. 13, that cargoes of it were sent to Leonatus, Craterus, and Meleager, the generals of Alexander the Great. Hist. du Commerce des Egyptiens, par Ameilhon, p. 253.

+ Rutty's Nat. Hist. of Dublin, vol. ii. p. 17, 22.

Dutton's Survey of Clare, p. 14.

M'Parlan's Survey of Donegal, p. 23.

country the basaltes is frequently seen in thick beds, and in this state it often separates into loose blocks, resembling that fossil known in Sweden by the name of trap; but for the most part it is entirely amorphous, and disposed, in large masses which do not split or separate in any assignable direction. At that singular phenomenon called the Giant's Causeway, and many other places, it appears in large pillars standing perpendicular to the horizon; but in some of the capes, and particularly near Ushet, in the isle of Raghery, they lie in an oblique position, and at the Doon Point, in the same island, and along the Ballintoy shore, they form a variety of regular curves. The little point of Doon is indeed exceedingly curious, as it exhibits pillars perpendicular, horizontal, and bending.*

The Causeway itself is generally described as a mole or quay projecting from the base of a steep promontory some hundred feet into the sea, and formed of perpendicular pillars of basaltes, which standing in contact with each other, exhibit a sort of polygonal pavement somewhat similar in appearance to a solid honey-comb. The pillars are irregular prisms of various denominations, from three to eight sides; but the hexagonal columns are as numerous as all the others together.+

On minute inspection each pillar is found to be separable into several joints, the articulation of which is remarkably neat and compact, the convex termination of one joint alays meeting with a concave socket in the next; and besides this the angles of one frequently project over those of the other; so that they are completely locked together, and can rarely be separated without fracturing the parts.

The sides of each column are unequal among themselves; but the contiguous sides of adjoining columns are always of equal dimensions, so as to touch in all their parts; and though the angles be of various magnitudes, the sum of the contiguous angles of adjoining pillars always makes up four right ones; so that there are no void spaces among the basaltes, the surface of the Causeway presenting a regular and compact pavement of polygon stones.

In regard to situation, the pillars at the Causeway stand on the level of the beach, and even under the surface of the ocean, whence they may be traced through every degree of elevation, to the summit of the highest grounds in the neighbourhood; as at the old fort of Dunmull, and on the top of Croaghmore, six or seven hundred feet above the level of the sea.

With respect to size, the perfect pillars of the Causeway are usually about a foot and a half in breadth, and thirty in length. Among the imperfect and irregular crystallizations found throughout the country, small prisms sometimes occur, which

* Hamilton's Letters on the Coast of Antrim, p. 73.

+ The triangular and octagonal pillars occur very rarely.

Hamilton's Letters, &c. p. 28.

do not exceed a few inches in breadth, and which in length are proportionally diinutive. In many of the capes and hills the size of the pillars is much larger than at the Causeway. At Fairhead they are of gigantic magnitude, often exceeding five feet in breadth, and two hundred in length.

"Of these vast columns the passage usually called Fhir Leith, or the Grey Man's Path, in the promontory of Fairhead, exhibits a magnificent example. It is a deep chasm dividing the solid promontory in twain; the upper termination of this singular passage is narrow, and barred over as it were by the fragment of a pillar, which having fallen across the fissure, remains suspended at an elevated situation. As one descends, the chasm widens and becomes more important; its solid walls of rude and threatening columns increase in height, regularity, and magnificence, until they attain to a perpendicular elevation of two hundred and twenty feet, conducting the passenger at length to the interesting heap of massive ruins which forms the base of the promontory itself, and exhaust the fury of the impetuous northern ocean.'

The leading features of this whole coast are the two great promontories of Bengore and Fairhead, which stand at the distance of eight miles from each other. The former lies about seven miles west of Ballycastle, and is generally described by seamen as an extensive head-land, running out from the coast a considerable way into the sea; but strictly speaking, it is made up of a number of lesser capes and bays, each having its own proper name, the whole of which forms what seamen denominate the Head of Bengore.

These capes are composed of different ranges of pillars, and a great number of strata; which, from the abruptness of the coast, are extremely conspicuous, and form an unrivalled pile of natural architecture, where all the regularity and elegance of art is united to the wild magnificence of nature. The most perfect of these capes is called Pleaskin. The summit of it is covered with a thin grassy sod, under which lies the natural basaltic rock, having generally a hard surface, somewhat cracked and shivered; at the depth of ten or twelve feet from the summit this rock begins to assume a columnar tendency, and forms a range of massy pillars of basaltes, which stand perpendicular to the horizon, presenting on the sharp face of the promontory, the appearance of a magnificent gallery or colonade upwards of sixty feet in height.

This colonade is supported on a solid base of coarse, black, irregular rock, near sixty feet thick, abounding in blebs and air-holes; but though comparatively irregular, it may be evidently observed to affect a peculiar figure, tending in many places to run into regular forms resembling the shooting of salts, and many other substances, during a hasty crystallization.

*Hamilton's Letters, p. 75, 76.

Under this great bed of stone stands a second range of pillars between forty and fifty feet in height, less gross and more exactly defined than those of the upper story; many of them on a close view emulating even the neatness of the columns of the Giant's Causeway. This lower range is borne on a layer of red ochre stone, which serves as a relief to shew it to great advantage.

These two admirable natural galleries, together with the interjacent mass of irregular rock, form a perpendicular height of one hundred and seventy feet; from the base of which the promontory, covered over with rock and grass, slopes down to the sea for the space of two hundred feet more, making in all a mass of nearly four hundred feet in height, which in beauty and the variety of its colouring, in elegance and singularity of arrangement, and in the extraordinary magnitude of its objects, can scarcely be rivalled by any thing of the kind at present known.

At the distance of eight miles, as already mentioned, the promontory of Fairhead raises its lofty summit more than five hundred feet above the sea, forming the eastern termination of Ballycastle Bay. It presents to view a vast mass of rude columnar stones extremely large, many of them exceeding two hundred feet in length, and in their texture so coarse as to resemble an imperfect compact granite, rather than the uniform fine-grained basaltes, which composes the Giant's Causeway. At the base of these gigantic columns lies a wild waste of natural ruins, of an enormous size, which in the course of successive ages have been tumbled down from their foundation, by storms, or some more powerful operations of nature. These massive bodies have sometimes withstood the shock of their fall, and are often seen lying in groups and clumps of pillars resembling many of the varieties of artificial ruins, and forming a very unique and striking landscape.*

The basaltes of the Giant's Causeway is a black ponderous stone, of an uniform close grain and hard texture, fusible per se, and pretty strongly magnetic. It does not effervesce in any of the mineral acids; it is free from animal or vegetable exuviæ; nor does it contain the slightest vestige of any organized substance whatever.+ According to the experiments of that able chemist Bergman, 100 parts of basaltes

119

From the metallic nature of this stone, it may be inferred, that the columns of the Giant's Causeway are all natural magnets, whose lower extremity is their north pole, and the upper extremity their south pole. For having stood during many ages in a perpendicular position, they must have acquired that polarity which is peculiar to all iron substances in a similar situation; and like natural magnets, every fragment when broken will have its north and south pole. "And this,"

says Mr. Hamilton, "I have found true by experience; each pillar in the Giant's Causeway, and each fragment of a pillar which I applied near to the needle, having its attractive and repellent point."

"Hence likewise it follows, that the great capes of this northern coast must possess a similar property; and accordingly in the semicircular bays of Benjore I have often found the compass to deviate very much from the meridian."*

Though basaltes itself has hitherto been of little use to man, it is accompanied with other substances, many of which, by, various modifications, derive their origin from it, and might be applied to some valuable purpose in economy or the arts. Among these may be mentioned thin strata of rich iron ores, of that species commonly called hamatites; other varieties resembling what are usually denominated bog ores, present themselves in greater abundance, and are found chiefly on the sides of the mountains and in the vallies. Ochres also, of several colours, prevail amid the basaltic beds, throughout different parts of the country. The predominant colour is red, varying from a dull ferruginous hue to the intensity of vermillion. There is much argil generally intermixed with these calces of iron, but instances occur where they are sufficiently pure to answer all the purposes of coarse paint. To these I shall add zeolites, found in the cells and cavities of the basaltes, in masses which weigh from a grain to a pound; an extensive tribe of clays, varying indefinitely in colour, tenacity, fusibility, and other properties, and a compound gritty powder, much resembling the pozzolana of Italy, or the terras of the Canary Islands. The last-mentioned substance, which results from a decomposition of the finer and softer particles of the basaltes, might, with proper attention, be employed for the same important uses as the before-mentioned volcanic products in sub-marine buildings and other works exposed to constant moisture. I shall close this list with one substance more, which, as it may be of use in ornamental architecture, deserves to be mentioned. It is calcareous earth united to the vitriolic acid deposited through the argil in strata of alabaster. This substance is found to answer for all the purposes of stucco, &c. equally well as the foreign gypsum.* Those desirous of farther information in regard to this wonderful phenomenon of nature, may consult the following papers in the Philosophical Transactions: Letter by Sir Richard Bulkeley, concerning the Giant's Causeway in Ireland, vol. xvii. n. 199, p. 708-710. An Account of the

* Hamilton's Letters, p. 82-91.