very curious facts detailed by Mr. De Luc': we fhall mention another.

"If rivers," fays the judicious author, "had formed vallies by erosion, the fame trata would always be found on both fides of the latter; and this, indeed, is fuppofed by Mr. Play fair, to be actually the cafe."

This remark is followed by a diftinct reference to a cafe in point, namely, the banks of the Avon, near Briflol; but innumerable other facts are adduced, to difprove the famebold affumption, and we can only fay, that to us they are completely fatisfactory. At p. 257, vol. 11. we meet with another conclufion, regularly deduced from data, capable of examination; we fhall give it in the author's own words, only premifing, that in the original it is immediately confronted with the oppofice hypothefis of Profellor Playfair, who feems to us remarkably fond of hypothefes, gueffes, and conjectures. We now ftate Mr. De Luc's conclufion, which is to the following effect.

"That from the origin of our continents, the ftreams formed by the land-waters have entered the fame channels, and difcharged themselves into the fea by the fame openings, through which we fee them flow at prefent. That thefe channels, and the openings themselves, were the effects of convulfions of the ftrata, not only antecedent to the time when thefe waters began to flow, but to the birth of the continents:-that thefe waters, fince they have begun to flow, have raifed their channels, instead of deepening" them ;-and that the fea, far from having encroached on the lands, has, on the contrary, been almoft every where removed to a distance from them."

Thefe facts are verified in the prefent books, by an ap peal to the very rivers named and infifted upon by Mr. Playfair; and fince the latter gentleman has thought proper to pafs by a number of Mr. De Luc's obfervations, previously oppofed to his fyftem, (or rather that of his friend Dr. Hutton,) we must declare, that unless he can contradict the facts here alledged against him, we must regard him as a most incompetent judge of the points in queftion, and a very bad philofopher; not to accufe him of any wilful mifreprese.tation of the phænomena he chofe to examine.

66

Another conclufion, directly oppofed to the Huttonian theory, Mr. De Luc eftablifhes, by his obferva ions, to the following purport, namely, that none of the materials carried off by rivers, from the continents to the fea, ever quit the coafts to pals down to the depths of the ocean.". Vol. 11. p. 396. But the following fummary of remarks, appli

cable

cable to all rivers, though deduced in the first inftance from an obfervation of the river Dart, is too important to be omitted.

"The first rivulets formed in mountains, flowed in channels, which must have existed before the birth of the continents, fince they have evidently been produced by anterior catastrophes of the ftrata. II. Whenever thefe rivulets, while still in the mountains, came to fpaces originally wide and horizontal, they depofited, as is afterwards the cafe with the largest ftreams formed by their union, all the materials brought down by them to those points, except the carthy particles, which float in running waters, and are depofited only in low vallies, or on the fea fhore. 111. No ftream, of whatever fize, has produced any demolitions in its courfe, but in places where it has met with fuch projections as have oppofed its paffage: and if thefe obftacles have made but little refiftance, it has attacked and carried them away. IV. It was in the earliest times, that the greatest quantity of ma terials were tranfported by running waters: because the chan nels into which they entered, being obftructed with rubbish, produced by anterior cataftrophes, they drove this down before them, to fpaces wider and lefs inclined; and also because the firft ftreams, formed on heights, covered with a loofe foil, washed it away in greater abundance, before it was bound by vegetation. V. Thus from the highest vallies of the mountains, down to the loweft, it evidently appears whence the materials have been brought, with which their bottoms have every where been raised, (rather than deepened,) in all the parts where the declivity was originally but fmall. VI. Laftly, thefe changes have been fo far from flow, that the known increase of the foils thus formed by the depofites of the waters, is one of the chronometers whereby it is demonftrated that our continents, at the birth of which all thefe operations began, are not of very great antiquity." Vol. 111. P. 99.

V

The ftratification of granite, a point of very great im. portance in geology, is very fatisfactorily proved, by a close examination of fome quarries near Truro, vol. i11. p. 189, &c. and other circumflances relating to this very extraor dinary fubflance are brought forward, as attefted upon the fpot by perfons of fingular eminence and knowledge, which undoubtedly tend directly to overthrow the arguments and conclufions of the Scotch theorists. Mr. De Luc's vifit to St. Michael's Mount in Cornwall, upon which excursion he was accompanied by Mr. Davies Giddy, a gentleman whose talents and acquirements are too well known to the world to be enlarged upon, is particularly interefling in regard to thele points; but it is impoffible to do juftice to the learned

1

author

author by any partial extracts. The book itfelf must be confulted. One of Mr. De Luc's general conclufions upon this particular fubject muft not, however, be omitted.

"There was no object more important to determine, in reference to the Huttonian theory, than the connexion of the granite with the fubftances which lie on it, as difcovered in mines; and it had, for this reafon, conftituted one of the principal motives of my journey into Cornwall. It is maintained in this theory, that no monument can poffibly be found of the first ope rations which took place on our globe; that all monuments now exifting, fhew only that continents have been destroyed, and new. ones formed of their materials, in an unlimited retrograde fuc. ceffion, infomuch that no trace remains of any origin of the ope rations of phyfical causes on the earth. This fyitem, however, only refts on the hypothefis that granite, the lowest of the fub ftances with which we are acquainted, has been raised up in a ftate of fufion under the ftrata of our prefent continents, the latter having been compofed of the detritus of more antient ones, by which they were preceded. Now this hypothefis is entirely fubverted by the phenomena above defcribed; and we are thus led back to the only fyftem reconcileable with all known facts, that which was firft fuggefted by M. De Sauffure, and in which I have acquicfced with a conviction established by all the phenomena that I have fince obferved; namely, that granite was the firft of the known chemical precipitations which took place in the liquid originally covering the whole globe; and that it was followed by the fucceffive precipitations of all the other kinds of ftrata. I have explained this fyftem in my Elementary Treatife of Geology, and traced its phyfical confequences, which I have fhewn to be in conftant agreement with precife monuments, from that first determined epoch to the prefent ftate of the earth." Vol. III,

P. 295.

We have already noticed, that the venerable author of thefe volumes, (who was in his eighty-first year when he performed thefe journeys in 1787,) appears from his account to have been travelling in a world of philofophers; every body having contributed their utmoft to further his views, and aflift him, as well as to accompany him, in his refearches. Lords and Ladies, Peers and Prelates, the Clergy, the Army and the Navy, the young and the old, were forward to give him every aid, not only in the way of hofpitality, but as feeling an intereft themselves in the objects of. his purfuits; from many he derived the most curious and important information, the fruits of their own experience and obfervations, and the English dress in which his Travels

Rr

BRIT. CRIT. VOL. XXXVIII. DEC. 1811.

now

now appear, is a ftriking proof of the higheft literary attainments, in a lady of the beft connections. We fhould hope, therefore, that the ftudy of nature, of geology in particular, which extends to the whole body of the earth, and may therefore be every where made the fubject of our remarks, would become general; that facts may be better understood, and the world at large be rendered more fecure, from the mifreprefentations of incompetent or rash theorists. Such scientific researches, though, under certain circumstances laborious and fatiguing, muft, in the nature of things, be continually prefenting to the view objects of particular curiofity and delight; many fuch are mentioned in these Travels, particularly the caverns of the Mendip hills, or Chedder cliffs, vol. 11. p. 410, and of Buckfastleigh in Devonshire, vol. III. p. 104. The author's account of the Logan stone on the Cape called Caftle Trereen, at the extremity of Cornwall, we fhall infert.

In approaching the Cape of Caftle Trereen, of which for fome time we had a fide view, I could not but be much struck with its appearance it confifts of a cluster of granitic pyramids, of a prodigious height, rifing from a common bafe, and refembling the towers of a gothic caftle; but when we reached it, my furprize was ftill greater; behind this fteep coaft begins a large combe, defcending eaftwards, and opening on the fame coaft. We firft went down into the upper part of this combe, which appears to form the moat of the caftle, under the outer wall, compofed alfo of rocks of granite. There we left our horfes, and entering a winding cleft in these rocks, we came out on a graffy fpace, where, by Mr. Price's order, a table-cloth had been spread, with an excellent cold dinner, but the scene which there fuddenly opened to our view, was fo magnificent, that for fome time it engroffed our whole attention...

"We had before us the pyramids of the Cape, called Castle Trereen, the fky forming the back ground; on one of them is the Logan ftone, to which the accefs is difficult, and would even be dangerous to many people, as a narrow ridge is to be af cended, with precipices on both fides; we did not attempt this; but Mr. Price had fent for a man of the country, who was accustomed to rock the ftone; he was already at his poft, and began the operation foon after we arrived. There is in the Pyramid a divifion, which, at the point where the ftone happens to be placed, is exactly of the proper breadth for a man to lean with his back against the folid wall, while placing himself in the posture of a chimney-fweeper, he preffes with his feet againft the ftone: it moves with the preffure, but in a degree perceptible only to the man himself, who yields when the ftone returns, being used to its ofcillating motions, and renews the preffure

every time that he feels it receding from him: and thus, by de grees, th ofcillations become very visible: from the fpot where we had placed ourfelves, we fiw them increafe, and they contitinued for fome time after the man had ceafed to prefs against the ftone.

"There is a great difference between individuals, with refpect to the manner in which their attention and feeling are excited by the objects of nature. When the man was about to rock the ftone, I had feated myfelf on the grafs, near the opening of the defile by which we had entered this fpice, it being an elevated fpot, immediately oppofite to the object of our attention, and commanding a full view of the flapendous feene around it. While I was admiring the whole of this profpect, I heard fome noife behind me; and turning my head, I faw a gentleman issue from the defile, followed by a lady in a riding-habit; they asked me whether this was the place where the Logan fone was to be feen? I fhewed them, on the oppoiite rocks, the man who had taken his ftation there; and having told them to fix their attention en him, because they would prefently fee him fet the stone in mo tion; I again turned my own eyes towards it; as foon as it began to ofcillate perceptibly, I looked back, intending to point it out to the curious ftrangers-but they were gone! It was quite enough for them to have been in the place where the Logan fone stood, and to be able to fay that they had feen it. In fact, that very evening, meeting them again at the inn at Penzance, where I was lodged, I asked the landlady who they were; fhe told me that they were travellers come from a distance of two hundred miles, to make the tour of Cornwall; and that they had been much pleafed with that day's excurfion, efpecially with having feen the Logan flone. There are many people who view objects of nature in a fiimilar manner; but it is to themfelves only that this is attended with difadvantage, provided they do not publifh fyftems refpecting the phenomena of which they have thus fnatched merely an imperfect view.”

We fhall fubjoin an abridged account of the author's vifit to Kinance Cove, where a very particular object attracted his attention.

"Kinance Cove is to the weft of the Lizard Point. Mr. Rogers withing to furprize me, had not defcribed to me the phe nomenon, which the ftate of the tide and wind (then very high,) had led him to expect; for Mr. R. afterwards told me that he had often brought travellers hither to fee it, who had been dif. appointed. Having gone round the obelifk at the fame height to which we had at firft afcended, we came to the brink of a deep chafm, defcending to its bafe; there I fuddenly heard a great fubterraneous rumbling; and before I had time to afk Mr. Rogers what it was, an immenfe fpout of water rofe through an