Page images
PDF
EPUB

mountains are volcanic productions; which we hope will tend to reconcile our anti-volcanic mineralogifts with Mr. Whiteburf's notions concerning the Toadfone.

The Author's hypothefis refpecting the lead fiffures in Derbyshire, which are horizontally interrupted by the toadstone, is certainly inadmiffible. He imagines that there was a fucceffive depofition of alternating lime and toadstone ftrata; and that the calcareous ones only broke into fiffures, which were fucceffively filled up with ore, and its concomitant parafitical cristallizations of spar and fluor. But how came it to pass that the calcareous only broke into fiffures, and that the toadftone ftrata remained unaffected? How can he account for the conftant, regular, and perpendicular run of the veins in fucceffive limeftone trata, though horizontally cut off and interrupted by toadftone beds?

We are not better fatisfied with his conjectures on the origin of fluor, which in Derbyshire is always found depofited in the fiffures, mixed and embodied with sparry criftallizations. We own that both are parafitical, and seem to have been depofited, where they are, at the fame time, and by the fame operation, the fame fluid, or folution; we are convinced that the sparry cristallizations, being of a calcareous nature, are fufficiently accounted for by the limeftone beds in which they are found; but it is impofiible for us to conclude with him, "that the fame limeftone folution fhould have depofited the fluor, which is of a quite different vitrefcent nature." I found, fays the Doctor, no vitrefcent fufible rocks whofe folution, mixed with that of the limeftone, could have accounted for thefe vitrefcent fluor cryftals. This was certainly his own fault, or rather a confequence of the hurry in which he made his obfervations in Derbyshire, or in which he wrote them down. The grit ftrata, which are uppermoft in Derbyfhire, and the fhale, clay, and toadstone beds, which interchange alternately with those of limestone, and which he has mentioned himfelf, p. 288, are certainly not calcareous but vitrefcent. Ra-pe.

ART. XIV.

Offervazioni del Sig Dottore Angelo Gualandris fopra il Monte Roffe uno degli Euganei del Padovano―dirette al Sig. Giovanni Arduini. Padova. 4to.

THE

HE Author publifhed this pamphlet before the appearance of his mineralogical travels; and we take notice of it, because this well-qualified obferver's account of Monte Roffo is drawn up with the niceft attention to fome circumftances, which feem not to have been properly attended to in Mr. John Strange's differtation on the fame fubject, Phil. Tranfa&t. 1775

Monte

1

[ocr errors][ocr errors][ocr errors]

Monte Roffo confifts partly of ftratified natural ftone pillars, which appear on different elevations, and rest on, and are interrupted by, large rocks of the fame fubftance that have no determined form. They are most of them pentagonal; but many have fix, and fome have four fides. They are of different lengths, and are articulated, as it were, in the fame manner as the bafalt-pillars in the Irish Giant's Causeway; nor are they more regular in their articulations, as thefe Irish bafaltes feem to be, which according to our Author, and, as he fays, contrary to many fpecimens, have been mifreprefented in the prints and defcriptions, as being all of them broken into regular convex and concave joints exactly fitting each other. Many of those in Monte Roffe are flat in their articulations; fome are flanting; fome are rudely convex and concave; fome are pyramidal; but whatever be the form of their articulations, the upper part conftantly fits the under part of the pillar to which it belongs, or on which it refts. Thefe ftrata of pillars reft, or are incumbent on, large rocks of the fame fubftance, which have no form, but what the accidental breaking, or the erofion of the weather feems to have given to them. At the foot of the mountain is a large quarry, where the fame rock is dug from compact vertical veins, or coherent ftrata, which feem to have been brought into a vertical position. In fhort, the fame kind of rock appears in Monte Roffe under very different forms, in the fame manner as the Bafaltes has been obferved to appear in many places; both kinds of rock have a columnar form only in certain fituations.

That of Monte Roffo is a kind of granitello, which is partly attracted by the loaditone. It confifts of a pale or afhcoloured hard pafte, mixed with fome whiitifh regular cryftallizations, fome hexagonal mica, and fome fmall prifms of black fhirl. Sometimes it is tinged with a fine greenish colour. Befide thefe cryftallizations it contains fome ftones, which Dr. Gualandris looks upon to be adventitious, and to have pre-existed before they were wrapt up in it. They are of two different kinds. Some have no regular form, and feem to be fragments of a rusty lava; fome very common ones are fmall yellow and greenifh cryftallizations, of the form of a parallelopiped. The marine falt and calcareous fpars are the only fubftances which are known to appear under that form; yet thefe cryftallizations feem to be of a different nature. They are not acted upon by acids, they refift the blow pipe, and differ from the marine falt and calcareous fparry cryftals, in being longitudinally ribbed or ftriped, and as they are found in the fame pafte with black fhirl, the Author is of opinion, that they are of the fhirl kind; for the fupport of which fuppofition, he might have mentioned the electrical fhirl from Saxony, which is ribbed and ftriped in the fame manner, though its form refembles rather a flattened cylinder,

without

Without entering into a more minute detail of the nature of thefe fingular rocks, the Author fufpects, and very justly in our opinion, that the columnar, as well as the other forms of this granitello, are to be looked upon as natural breaks or fiffures, determined partly by the nature of its conftituent parts, and partly by its refpective fituation, or other particular circumftances. By these he understands a more or lefs fudden cooling of the whole mafs; which he, like other Italian naturalifts and obfervers, fupposes to have been in a state of fufion. He had obferved in the iron founderies at Bergamo, that mafies of caft iron, when heated and thrown into cold water, will crack and break; and that the fame iron mass exhibits a very various internal texture: the inner parts appearing as it were, fibrous, ftriated, and cryftallized; whereas the more external parts are fimply granulated, and in lefs determined forms.

We remember to have read a nearly fimilar hypothesis on the origin of the columnar Bafaltes *, which, fince its publication in England, has been adopted in France by M. Fougeroux, in his late publication on the ancient volcanos in Auvergne; and we cannot deny it our affent, because it is established upon facts and analogy. If the whole mafs of granitello in Monte Roffo had been in fufion, and cooled at once, its inner parts alone must appear to be a group of columns; which not being the cafe, the Author very judiciously doubts, whether Mr. Strange's hypothefis is admiffible, supposing that the whole mafs had undergone a local ignition and alteration in the fame place where we fee it at prefent; and he is of opinion, that it was accumulated by fucceffive volcanic eruptions: which however the Author should have more carefully proved than by bare affertion; for he could not be ignorant, that homogeneous maffes of clay or stone, brought to a state of liquidity by water or fire, and hardening again by drying or cooling, will equally affect a variety and regularity of forms.

We are as little fatisfied with his affertion concerning the parallelopiped crystals in the mafs of the granitello, which he is pofitive in declaring to be adventitious pre-exifting bodies in the fame form we see them, before they were wrapt up in the molten granitello or lava mafs. Meflrs. Ferber, Rafpe, and Sir William Hamilton, had looked upon different fpecies of fhirl crystallizations, which are found in the Vefuvian and other lavas, not as having pre-exifted, but as having been produced in their cooling and congealing maffes. We must refer to their publications, where they have specified thofe particular fhirl kinds, and the reasons and grounds of their hypothefis. As far we re

* See Rafpe's Account of fome German Volcanos. London. 1776. and our Review, vol. liv, p. 475.

member,

[ocr errors][ocr errors]

member, they never afferted that the granitello of Monte Roffo and the Vefuvian lavas are of the fame kind; or, in particular, that the ftriated parallelopiped crystals of Monte Roffo ought to be ranked amongst their volcanic fhirls. Yet Dr. Gualandris charges them with that affertion, and boldly denies his affent to their hypothefis on the formation of other fhirl kinds, though it is well fupported by fome facts they have given, and by the analogy of certain cryftallizations, which are undeniably produced in the melting pots of the glasshouses. They were firft obferved by Mr. Keir, who defcribed them in a differtation, which, about two years ago, was prefented to the Royal Society. Dr. Gualandris had an opportunity of feeing many famples of thefeglafs cryftallizations in Mr. Greville's noble collection in London. He himself agrees, that "to all appearances they are certainly produced in the mafs of glafs when in a state of fufion; yet he will not allow the above naturalifts to draw from them any analogical conclufions in favour of their volcanic crystallizations: becaufe, fays be, the glass, which served as a menftruum in the crystallization of thefe figured bodies was homogeneous, and in a perfect state of fufion; whereas the lavas are rather hetorogeneous mixtures, fcarce affected by the fire, and at most a thick paste, not at all reduced to any tolerable degree of liquidity, which the cryftallization abfolutely requires, and which to fuppofe, he declares to be against reafon and common fenfe." We have nothing to reply to all this, except that glass is no more a homogeneous mixture and body than lavas are; that the very cryftallizations produced in it prove it to conviction; that the mixture of lavas evidently is and must be very various; that the poffible degree of their liquidity, which has not yet been afcertained, is and must be in proportion to the degree of heat, which they may undergo; and that we cannot take upon us to agree with Dr. Gualandris in his round affertions, which he himfelf acknowledges to be unfupported by chemical experiments.

We are better and fully fatisfied with his very fenfible remarks on the difference of granite and granitello; and we congratulate the univerfity of Padua on having produced fo valuable and learned an obferver of nature.

See Ferber's Mineralogical Travels to Italy, Rafpe's Account of fome German Volcanos, and Sir William Hamilton's Campi Phlegrai.

Ra-pe.

ART.

[ocr errors]

ART. XV.

Differtatio Phyfiologico-Medica Inauguralis, De Menfibus ex Materia quadam peculiari. Ovariis Societa, oriundis, A Physiologico-Medical Inaugural Differtation, on the Origin of the Menfes, from a certain peculiar matter, fecreted by the Ovaries. By Phoebus Hetzerus Themmen, of Groningen. 8vo. Leyden. 1781.

THE

HE ingenious Author of this thefis, after propofing and attempting to overthrow the common theories of the menftrual Aux, offers his own, which is, that a certain matter fecreted by the ovaries, and periodically defcending into the uterus, is the caufe, as well of the venereal appetite, as of the menfes. The fanguineous discharge therefore, according to him, is only a kind of concomitant circumftance, and not effentially neceffary to the fulfilment of this great law of the female conftitution. This is not the place for entering into particular arguments for or against our Author's hypothefis; which, probably will fhare the fate of many an ingenious conjecture, not thoroughly compatible with the phenomena of

nature.

A.

CORRESPONDENCE.

R. D. obferving in the Review for November last, a note from our correfpondent-Nimrod,obferves, that Peter Beckford, Efq; of Stapleton, Dorfetfhire, fon of Julinis or Julianus Beckford, and nephew of the late celebrated Alderman of that name, the professed author of Thoughts on Hunting, is not the Mr. Beckford to whom Mr. Brydone addreffes his letters, nor are they relations.

He is fon-in-law of the prefent Lord Rivers, and has prefixed to his book an exceeding good print of Mrs. Beckford, his wife, one of the handfomeft women, and best of wives, in the Weft of England. R. D. expreffes his concern that we fhould have been mifled, by a correfpondent, in a defcription of the real or professed author of Thoughts on Hunting, and he remarks that there is another book on the fame fubject, (but rather on hare hunting) of which the Review has not, as yet, taken any notice. That Mr. B. of Stapleton is undoubtedly the author of Thoughts on Hunting; but he does not hear who is the author of that other work. If fays he, you think proper to afcertain the author, by diftinguishing him from William Beckford, Efq; of Effex, you may do Mr. Peter Beckford a favour, by afcribing to him the honour of this first effay on this fubject in English, and oblige a conftant reader."

We shall speedily give fome account of the book on Hunting, alluded to in the latter part of the foregoing letter. It is entitled Essays on Hunting.' Southampton, printed.

« PreviousContinue »