length, fupprefs any natural reflection. This may render his work more voluminous than it otherwife would have been ; but it renders it, at the fame time, more entertaining; and thefe incidental objects and reflections ferve as a refreshment and interlude between profound and ferious difquifitions. Our Author's account of the miners of Claufhal, and, in general, of the mines of Hartz, and the manner of working them, is curious and instructive and his obfervation of the primordial and fecondary mountains, the former in the chains of Hartz, and the latter in the Kahlenberg, is a new refutation of the hypothesis of thofe, who attribute the prefent form of our continents, and the origin of all their mountains, to the operation of the waters alone. The eighth part contains the fecond journey of M. Dɛ Luc in Holland and Germany, by a different route, by Helvoet, Grave, Ofnabrug, Hanover, Pyrmont, Munden, Caffil, Francfort, Heidelberg, Manheim, Mentz, Coblentz, Cologn, Juliers, Maeftricht, Tongres, and Bruffels. The principal things that we meet with here, are certain particularities, and reflections relative to heaths and the foil that they cover, to the mineral waters of Pyrmont, to the veftiges of volcanic erruptions in fome parts of that route, and in the mountain of Caffel, as alfo, along the borders of the Rhine from Coblentz to Cologn. Several incidental details of a moral and fociat kind embellish this part; that which relates the meeting with Peternel Van de Schans, a hofpitable goody, is the only one that may be thought an-interefting; and fuch it will appear to many readers. The ninth part is the largest of all, and takes up entirely the fourth volume. It contains, in thirty letters, our Author's third voyage into Holland and Germany; and as, in this voyage, he pafled through, nearly, the fame places that he had formerly vifited, it was not poffible that he should avoid repetitions. But as thefe repetitions throw new light upon objects, which had been viewed with more or lefs rapidity, and deferved to be made farther known, they merit rather the name of illuftrations; and, indeed, the points of view prefented to our Author, and his obfervations upon them, in this third voyage, are every way adapted to fatisfy a curiofity that was fill left in the expectation and defire of farther information. The principal objects exhibited here, are-A defcription of the coaft of Harwic confidered, with refpect to the diminutions or acceffions which it has undergone or received; and remarks on the concretions that are contained in the foil of that coaft-Aa Hydraulic defcription of Holland-Reflections on the ftate of the heaths in the low and uncultivated parts of Brabant, and the high and cultivated diftricts in the neighbourhood of Tongres (whofe environs our Author has examined with the most fingular and laborious attention, and perfectly refuted the ancient tradi tion, that the fea formerly came up to its walls).-Moral reafons for examining the formation of the earth.-Farther remarks on the volcanos on the banks of the Rhine, and on the formation of the Bafaltes.-Volcanic erruptions in the Schifous mountains along the Rhine, and volcanic foil in regular trata between Andernach and the lake of Loch; and a defcription of the volcanos and volcanic phenomena in the neighbourhood of this lake.-The quarries of Trafs, and the volcanos in their environs, (in the road from Nieder-Mennich to Neu Wied*).— Rocks filled with marine bodies, though in ftrata, almoft vertical like thofe of the Schifles.-Continuation of the volcanos, at the back of the natural mountains, on the western fide of the Rhine between Andernach and Oberwinter.-Mountains of Bazaltes on the fide of the Rhine, oppofite to Oberwinter. -An effay on earthquakes.-Hills of lime-ftone near Mentz, that confirm our Author's account of the mechanism of petrifaction, and other matters of a like nature. The fifth Volume comprehends the tenth and the eleventh parts of this work. The tenth contains the obfervations made by our Author, in a fourth Tour in Germany, and on the coafts of the northern ocean. Here the natural hiftorian will follow him with pleasure, in his defcription of the mountains in the counties of Paderborn and La Lippe, of the heaths of Luneburg and Winfen, of the duchy of Bremen, and of the cosmological phenomena, which he found at Alteland, near Stade ;-in his defcriptions of the Kedinger:noor and Duvelfmoor (which fignify the Turberies of Keding and the Devil); in his voyage through Oldenburg, Eaft-Friesland, Delfzyl, Groningen, Friesland, and Holland; as alfo in his route from Utrecht to Pyrmont, and from Pyrmont to Aix la-Chapelle, by Geifmar, Wisbaden, and Coblentz. To all this are fubjoined fome letters from M. Trofon to our Author, concerning the ancient volcanos, which lie north-east of Coblentz, and the ftrata of pumice-ftone that are to be seen on the banks of the Rhine and the Mofelle; and this Part is terminated by a defcription of the country and foil between Aix-la-Chapelle and Calais. From all the obfervations made in thefe voyages, M. De Luc has been confirmed in his opinion, that our continents are not of a very ancient date-and that not one of the caufes, which are known to act upon, and influence our globe, and which, by * At Neuwied, there is a Moravian community, which our Author reprefents in pleafing colours, obferving, that it is rather on benevolence of character than on peculiarity of opinion, that the affociation of the Moravian brethren and fitters is founded. -This is, certainly, the most favourable way of reprefenting the Moraviansand we hope, and begin to believe, that it is a true one. APP. Rev. Vol. lxii. Nn their their nature, must have acted upon it formerly, as they do now, could have produced the univerfal change of land into fea, and fea into land, which has undoubtedly taken place, and of which the vestiges are evident. What then is the extraordinary cause that operated this revolution in the furface of our globe? This question our Author anfwers in the eleventh and Jaft Part, by producing his hypothefis, the refult of a long and laborious ftudy of nature, and for which he has prepared the reader in the preceding volumes. The facts and conclufions deducible from the obfervations related in the preceding volumes, may be reduced to the following. The existence of marine productions in our continents, and even in the fummits of mountains, indicates a change in our globe, and fuppofe a caufe that placed them there. Thefe marine bodies are inclofed in certain fubstances well known, and entirely diftinct from them, which fubftances furround them perfectly, and even fometimes fill their little cavities; and therefore, thefe fubftances were in a ftate of foftness or fufion when they inclofed thefe marine bodies.-The natural arrangement of thefe fubftances is in regular parallel beds, or ftrata, often horizontal, always a little inclined, fuch, in a word, as the waters form, when they remove any quantities of matter from one place to another, and fuch as they alone form : this arrangement, according to our Author, is due to them. In thefe beds the fragments of primordial fubftances are difcovered, and therefore thefe latter exifted as they are before thefe beds were formed.-The fragments of the primordial fubftances, found in thefe beds, though they appear, by undoubted marks, to have belonged to larger maffes, have their angles blunted by friction, and thus appear to have been rolled by the waters that formed thefe beds;-and as this operation required time, it was not by fudden shocks or movements, that the waters formed the beds, which contain the fragments under confideration.-Thefe depofits made by the waters have been raised, one above the other, even fo as to form high mountains, whose compofition is the fame from the fummit to the bafe; therefore the waters that formed them were deep, and a confiderable fpace of time was taken up in their formation.-These mountains contain alfo marine fubftances, throughout, but unequally diftributed; and the fame inequality is obfervable in the ftrata of the plains and hills: fome of thefe ftrata contain almost an equal mixture of marine and earthy fubftances: others contain few or none of the former: fometimes the fhells are of one kind at other times, of various forts;-frequently there is a mixture young, old, entire, and broken, with all the marks of the accidents that happen to them in the ocean, &c. "Therefore Our δε our continents have once been the bottom of a fea, on which 66 every thing paffed in the fame manner, as things pass on the "prefent bottom of the ocean."-Among the marine bodies, depofited in the bottom of the fea that is now become our continent, there are feveral kinds, that only live in the feas, that are far diftant from it. "Therefore, the fea, that covered our continent, did not withdraw from it flowly; for, by fuch a gentle retreat, the marine animals that lived in it would "have continued to live in it, and we fhould find in the waters, "that are near our coafts, the kinds, whofe fragments and car"cafes we discover in the contiguous lands."-9. We find alfo, in the earth, even near the fea-coafts, marine, fofile, animal, bodies, of fpecies which we have not as yet difcovered living in any fea,-though it would feem, that, did they exift, they would not have efcaped the notice of men. "There muft, "therefore, have been caufe, which made the fea to with"draw itself from our prefent continents; fome circumstances, "alfo, which have either deftroyed thefe marine animals, or con"cealed them from our view, or changed their aspect."-10. If we confider the external form of our continents, we fhall not find in the whole, taken together, any thing that denotes the fea's having withdrawn from them in a violent manner. They confift of a great number of hills and plains, composed of ftrata or layers of fand (or other unconnected matters) which have not undergone any confufion. We fee no great opening extending itself towards the prefent ocean, and even the greatest part of the rivers must have formed their own beds in order to arrive at it." From hence it follows, according to our Au thor, that, though it be evident, that the fea has not with❝ drawn itself from our continents, in a revolution extremely "flow and fucceffive, it appears, nevertheless, on the other hand, that its removal was not attended with a fudden paffage "of the whole mafs of the ocean into a new bed."-11. We perceive, at the furface of our continents, a prodigious quantity of accumulations different from the preceding, which have been undoubtedly expofed to the action of fire, which is now quite extinguished, and neither history nor the most ancient traditions convey any notice of the time when these mountains were formed. "Therefore, there is a clafs of volcanic moun"tains, whofe origin has probably been always unknown."12. These mountains have marks, that diftinguish them from the volcanos that burn ftill: more particularly, they are often covered with accumulations of diftinct fubftances, which are the work of the sea. "Therefore the fea has alfo covered this particular clafs of volcanic mountains:" and feveral circumftances indicated by our Author, fhew that these mountains were formed, when our continents were yet the bed of the Nn 2 ocean: ocean for their ftrata discover alternate marks of the operations of fire and water; and there are examples on record, of fuch mountains arifing from the bottom of the fea.-13. It appears by a variety of phenomena, mentioned by our Author," that the prefent continents have their primordial base precisely where it was, when it conftituted the foundation of the "ancient ocean, and that it is upon this ftable and permanent "bafe, that the fecondary eminences, produced, fome by fire "and others by water, have been raifed."-It appears farther, that when the fea produced its laft accumulations of calcareous matter and fand, upon our continents, it then occupied these continents entirely.-Again-as foils, difengaged from water, and exposed to the influence of the air, are covered, in process of time, with plants, whofe fucceffive generations, left upon the place, produce ftrata of vegetable earth, these ftrata, when they remain untouched, affist us in calculating, by their progreffive growth, the time that a foil has been expofed to the influence of the air. Accordingly, by confidering, not the mountains, where, from various caufes, vegetation does not follow a uniform rule, but the laft frata of fand which the fea has spread over extenfive diftricts of our continent; our Author concludes, from a variety of circumftances here fpecified, that the time elapfed, fince thefe ftrata have been expofed to the influences of the air, is not fo confiderable as fome have imagined, and that all the extent of the base of our continents was thus exposed at one and the fame period. An obfervation alfo of the phenomena, that are difcernible on the borders of the prefent ocean, have led our Author to conclude, that the level of the fea undergoes no more alterations, that fince it left our continents it difcovers no tendency to change its bed, and that the period when it left our continents is not extremely remote. The refult of all these phenomena is reduced, by our Author, to the following propofitions.-1. The fea covered formerly our continents, and covers them no more.-2. There exifted, at the fame time, other continents, that feem to exift no more.-3. The fea occupies a bed, in which it is permanent, and there is no difcernible caufe that has a tendeney either to deftroy this bed or to form a new one.-4. The revolution that produced this new ftate of things, must have affected, at the fame time, all the parts of our continents, where the untouched layer of vegetable earth is of the fame thickness.-5. The thickness of that layer or Aratum is not very confiderable, if we attend to the known effects of the cause that produced it. M. DE Luc's fystem may be then expreffed in the following fentence: Ancient continents, which were contemporary with the ancient sea, funk, or fell in below the level of its bed: and the fea, flowing into that |