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which formed the, communication between Ireland and the Hebrides, among which Staffa is diftinguished for ftupendous columns, though inferior to thofe of Antrim, is a natural and obvious thought. It required no knowledge of latitudes and longitudes;' for any two points could furely be connected by a ftrait line. It was more inexcufable to attribute them to melting lava, cooled in the fea; fince the forms of melted matter, thus fuddenly cooled, are confused and irregular. The fea, indeed, probably difcovered them at this place, by washing away thofe parts of the earth by which they were furrounded, for they are chiefly found in the most expofed fituations; but it has no other connection with them. Mr. de Buffon's opinion, that they are formed by streams of lava pouring over a cliff into the fea, is inconfiftent with the 'appearances, and unworthy of its author. Independent of Ireland and Staffa, bafaltic columns are found in Silefia near Luben and Wife; in Marienburg and Weilburg, in Naffau in Lauterbach, Bliften, and other parts of Heffe and Lufatia; in Bohemia, and on the frontiers of Saxony; on the borders of the Rhine, between Andernach and Bonn; in Languedoc and Auvergne, at Velay and Vivarais. We omit the bafaltic appearances in various parts of Italy, because they are in the vicinity of water; and what travellers have related of fimilar mountains in Spain and Portugal, is scarcely clear enough to engage our attention. The cause of these ftupendous appearances is, we fear, ftill uncertain: there is little doubt but that they are of volcanic origin, though this opinion is oppofed by Bergman. He found this ftone fimilar to the Swedish trapp, which had not undergone any calcination; and the fpecimens fent to him were without pores. The Swedish trapp is a schorl, fo called from its form, which is generally near that of a trapezium: it is the born-stone of Wallerius, a fanciful and improper term, taken from its want of brittleness. There is, indeed, little doubt of the facts: the Swedish trapp has never been melted, and it is exactly fimilar to the bafalt in its constituent parts. In these ref pects, Mr. Sauffere steps to our affiftance; and we learn that this ftone really melts into a fubftance very similar in texture to the bafaltes, without any deftruction of its parts. In fact, he has imitated the feveral volcanic productions, by melting the different ftones from the more impure granites to the Killas rock. Mr. Hamilton corrects an error, both in Faujas de St. Fond, and Bergman, who have faid that hafalt is without pores: when examined by a microscope, or very highly polished, they are generally found; but we ftrongly fufpect, that in the lower and denfer parts of the columnar

mafs,

mafs, the pores may have entirely disappeared, though they preferve the diftinctions of lavas by becoming more confpicuous as we approach the furface.

Mr. Hamilton thinks, that these columns are formed by crystallization of the lava in cooling; for he fupports the opinion which we have endeavoured to rescue from the objections of Bergman, by very forcible arguments. The theory of cryftallization is fo old, that in fome figures of bafaltes, the columns are reprefented as ending in pyramids; but though old, we fear it is not tenable. We know no inftance of cryftallization, where there are no confiderable vacuities. Those metals which feem to cryftallize in cooling, expand in the procefs; bafaltes, in fome instances, do the fame, for the upper furface is convex ; but it is very certainly fometimes flat, and in others without perceptible pores, We are told by Sauffure, that the particles of which the compactest granite is formed cryftallize together; and, by Bergman, that the earth of precious ftones is ftrongly concreted in the fame manner; but thefe operations are little understood, and it is rather an abufe of language to apply the fame term to fuch different proceffes, which must be effected in very different ways. Faujas de St. Fond objects to this opinion, on account of the planes and the angles being different both in fize and number, while, in the strict operation of crystallization, there is a remarkable confiftency in both, particularly in the angles, as Romè de l'ffle has proudly boasted:' befides prifms, he obferves, are never found without being crowned with a pyramid. We ought to select our author's answer to fome of the objections to this theory.

The only apparent fpecific difference between the bafaltic cryftals, and those which are produced in our diminutive elaboratories, feems to be, in the complete difunion of the pillars, and in the articulated form which they fometimes exhibit. But this will not appear to be a matter of any importance, when we reflect, that in natural operations of the fame kind, but differing in magnitude, the fame proportions are commonly obferved between the different parts: thus, the fame ratio, which the diameter of a bafaltic pillar bears to the diameter of one of our diminutive cryftallizations, will the interval between the pillars of bafaltes bear, to the interval between the parts of our crystals; and whoever will take the trouble to calculate this distance, will find it fo very fmall, às eafily to admit the different furfaces within the limits of cohesion; so that no feparability of our cryftals into joints can poffibly take place, from their fmall nefs, though they often bear marks which might lead one to imagine them capable of difunion.'

VOL. LXI. March, 1786

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Again,

Again,

A fecond objection arifes from hence, that the currents of lava which have iffued from Etna and Vefuvius, within the memory of man, have never been known to exhibit this regularity of arrangement. It is therefore faid that experience does abundantly prove the fallacy of the volcanic hypothesis.

In reply to this we are told, that it is not in the erupted torrents of these volcanoes we are to look for the phænomena of crystallization, but in the interior parts of the mountains themselves, and under the furface of the earth, where the metallic particles of the lava havenot been dephlogifticated by the access of fresh air, and where perfect reft, and the most gradual diminution of temperature, have permitted the parts of the melted mafs to exert their proper laws of arrangement, so as to affume the form of columnar lava: that we must wait, until thofe volcanic mountains, which at prefent burn with fo much. fury, fhall have completed the period of their existence; until the immenfe vaults, which now lie within their bowels, no longer able to fupport the incumbent weight, fhall fall in, and difclofe to view the wonders of the fubterranean world: and then may we expect to behold all the varieties of cryftallization, fuch as muft needs take place in thefe vaft laboratories of nature; then may we hope to fee banks and causeways of bafaltes, and all the bold, and uncommon beauties, which the abrupt promontories of Antrim now exhibit.'

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Thefe difficulties have contributed to fupport the more mo dern opinion that they have affumed this form by retraction, probably, by contraction in cooling. Faujas de St. Fond trongly fupports this opinion; and, in the neighbourhood of Vivarais, found a piece of granite actually divided by the feparation of two neighbouring prifms. Sauffure, who has examined the operations of nature with, confiderable precision, agrees in the fame opinion; and even endeavours to explain the reafon of it. As the work is not common in England, we fhall tranflate the paffage. The tendency to divide, by a kind of retraction, into fragments, more or lefs regular, terminated by planes, is a property of argillaceous earth; and this earth communicates the tendency to all the minerals with which it is mixed. We find it even in bafaltes produced, as we have seen, by the fufion of rocks combined with argill, in ether words, the horn ftone.' We fhall not decide on these subjects; though we copfefs, if the irregularity is an obftacle to their being formed by cryftallization, they are too regular to be produced by contraction in cooling. We need not enlarge on Bergman, or Kirwan's opinion; though both are ingenious, they are not fo probable as thofe we have detailed. We ought, indeed, to apologise for our digreffion; but as the

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object

object of a Review is to give an account of the present state of fcience, and as we have not had an opportunity of enlarging. on the fubject fince the publication of fome important works, we hope it may be excufed.

Mr. Hamilton proceeds to give an account of the other mineral productions of this country, and he defcribes them with great clearness and precision: we are forry, that the length of this article prevents us from being more particular on the fubject. The concluding letter affumes a higher tone, and vindicates

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' the ways of God to man.'

He speaks to the fceptic in bold energetic language, and with ftriking arguments and pertinent inftances, shows, that the structure of the earth difplays confummate wifdom ; that its hiftory, as well as the hiftory of its inhabitants, is favourable both to natural and revealed religion, -Such are these interesting Letters, which we cannot recommend inore forcibly, than by their having engaged fo large a share of our attention, at a busy and a troublesome period of our an-.. nual labour...

Dei Cataclifmi fofferti dal Noftro Pianeta Saggio Poetico, per fervire di Prodromo a un Poema Filofophico e Theologico. A Poetical Sketch of the Revolutions that have happened in the Natural History of our Planet; intended as a Specimen of a Philofophical and Theological Poem. 8vo. 2s. Crutwell, Bath.

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Τ' HIS performance, of which we have both the original and the copy, is fomewhat extraordinary.-It contains the plan of a philofophical poem, intended to have been written in Italian blank verfe; in which the author designed to have compiled a theory of the changes that have taken place in our globe, and to reconcile to our reafon, by the affiftance of ancient mythology, the various and intricate phænomena which the foffile kingdom prefents.' It was to have been completed in twelve books, and from feveral paffages, as well as from his many other performances, we may perceive that the author, Il Signor Abbate Fortis, was neither defective in learning, nor brilliancy of fancy. He was a native of Venice, and published a Tour into Dalmatia-he is now dead, and of courfe nothing farther, at least from him, can be expected toward filling up the prefent very imperfect outlines. pears indeed never to have been his intention, for he concludes his ketch with informing us, that

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The defign of this poem is not, and probably never will be completed. The author has fo far abandoned all thoughts of it, that he has for fome time ceafed to work at it, and it is more than probable that this fituation will compel him to content himself with the sketch he has put into verse, withbut making farther progrefs.'.. 1.' erving po 240. Hi What thofe circumftances were to which he alludes, we know not→→poffibly a narrow income, and laborious avocations. The difficulty of the tafk alone would have been, indeed, a fufficient reafon for relinquishing the attempt. To wield the machines that are here propofed to have been introduced, required nos common hand. The neceffary exertions were evident, but the fuccefs of them by no means clear. Had the plan been completed, we apprehend, it would have been more curious than entertaining, more fcientific than poetical. To a few philofophic minds it might have appeared instructive andamufings to the million, wild, confuled, and uninterefting. Of the tranflator's abilities the following poetic fragments, and there are many fuch occafionallyscattered through the arguments of the different books, will give ne unfavourable idea. The gnomes are thus introduced as bringing offerings to Pluto, bas,bstolɔ zi 1oob 9.42,29ɔur -Strack with his ebon Wand,ni mig? Lo the firm granite cleaves at his command 2 oth In hideous yawn. Earth opes her inmoft stores, Esido And at his feet her choiceft treaftres pours. 09 buf $555659

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Forth come the gnomes-their tribute they prepare,
Beings
s' compos'd of neither earth nor air plus va
The various vapours of the falph'rous minev
To form thefe hated prites their powers combine.
The blaze these glittering gems diffuse arcando
Illumines, far and near, the dark profound, vas
And the grim troop in hideous lustre thews.
Thus have } feen, where Pola's towers once rofe,
As er't, with penfive fteps I've wandered o'er
Each mould'ring arch, and time worn corridor, vi
Declining Phobos, with a pallid gleam, o ber
On fome poor lazar dart cblique his beam;
Who, wretched tenant of thofe glittering plains,
'Gaint the proud porch his pally'd limbs fuftains.
Next comes a troop, whofe bending fhoulders bore
The ponderous burden of each various ore,
Gold's pureft mafs,-pale filver's virgin fnow,
And ruddy copper-thefe unbler.ded grow
Deep in earth's caves, from whence the branching vein
Tempts and rewards the anxious miner's pain.'

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