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mountains are volcanic productions; which we hope will tend to reconcile our anti-volcanic mineralogists with Mr. Wbitihurst's notions concerning the Toadstone.

The Author's hypothesis respecting the lead fissures in Derbyshire, which are horizontally interrupted by the toadstone, is certainly inadmissible. He imagines that there was a succes. five depofition of alternating lime and toadstone strata ; and that the calcareous ones only broke into fiffures, which were fuccef. fively filled up with ore, and its concomitant parasitical cristalJizations of spar and fuor. But how came it to pass that the calcareous only broke into fissures, and that the toadftone trata remained unaffected ? How can he account for the constant, regular, and perpendicular run of the veins in succeffive limeftone ftrata, though horizontally cut off and interrupted by toadftone beds ?

We are not better satisfied with his conjectures on the origin of fuor, which in Derbyshire is always found deposited in the fissures, mixed and embodied with sparry cristallizations. We own that both are parasitical, and seem to have been depofred, where they are, at the same time, and by the same operation, the same fluid, or solution; we are convinced that the sparry cristallizations, being of a calcareous nature, are sufficiently accounted for by the limestone beds in which they are found; but it is impoflible for us to conclude with him, “that the same limeftone solution should have deposited the fuor, which is of a quite different vitrescent nature." I found, says the Doctor, no vitrescent fusible rocks whose solution, mixed with that of the limestone, could have accounted for these vitrescent ftuor crystals. This was certainly his own fauit, or rather a confequence of the hurry in which he made his observations in Derbyshire, or in which he wrote them down. The grit strata, which are uppermost in Derbyshire, and the shale, clay, and toadstone beds, which interchange alternately with those of limestone, and which he has mentioned himself, p. 288, are certainly not calcareous but vitrescent.

Talope,

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A RT. XIV. Ofervazioni del Sig Dottore Angelo Gualandris Jopra il Monte Rollo uno

degli Euganei del Padovano-dirette al Sig. Giovanni Arduini. Pa. dova. 4to.

H E Author published this pamphlet before the appearance I of his mineralogical travels ; and we take notice of it, because this well.qualified observer's account of Monte Roffo is drawn up with the nicest attention to some circumstances, which feem not to have been properly attended to in Mr. John Strange's dissertation on the same subject, Phil. Tranfact. 1775.

Monte

have fix, and. They are mot lame substance chi and are in

Monte Raffo consists partly of stratified natural stone pillars, which appear on different elevations, and rest on, and are in. terrupted by, large rocks of the same substance that have no determined form. They are most of them pentagonal; but many have fix, and some have four sides. They are of different lengths, and are articulared, as it were, in the same manner as the basale-pillars in the Irish Giant's Causeway; nor are they more regular in their articulations, as these Irish basaltes seem to be, which according to our Author, and, as he says, contrary to many specimens, have been misrepresented in the prints and dela cripcions, as being all of them broken into regular convex and concave joints exactly fitting each other. Many of those in Monte Rollo are flat in their articulations; some are Nanting; some are rudely convex and concave; some are pyramidal; but whatever be the form of their articulations, the upper part constantly fits the under part of the pillar to which it belongs, or on which it rests. These strata of pillars reft, or are incumbent on, large rocks of the same subftance, which have no form, but what the accidental breaking, or the erosion of the weather seems to have given to them. At the foot of the mountain is a large quarry, where the same rock is dug from compact vertical veins, or coherent strata, which seem to have been brought into a vertical position. In short, the same kind of rock appears in Monte Rosso under very different forms, in the same manner as the Basaltes has been observed to appear in many places ; both kinds of rock have a columnar form only in certain situations.

That of Monte Rolo is a kind of granitello, which is partly attracted by the loadstone. It consists of a pale or afhcoloured hard pafte, mixed with some whiitish regular crystallizations, some hexagonal mica, and some small prisms of black shiri. Sometimes it is tinged with a fine greenish colour. Beside these cryftallizations it contains some stones, 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 seem to be fragments of a rusty lava ; some very common ones are small yellow and greenish crystallizations, of the form of a parallelopiped. The marine falt and calcareous spars are the only substances which are known to appear under that form ; yet these crystallizations seem to be of a different nature. They are not acted upon by acids, they resist the blow pipe, and differ from the marine salt and calcareous sparry crystals, in being longitudinally ribbed or striped, and as they are found in the same paste with black shirl, the Author is of opinion, that they are of the shirl kind; for the support of which supposition, he might have mentioned the electrical Thirl from Saxony, which is ribbed and striped in the same manner, though its form resembles rather a Rattened cylinder,

without Without entering into a more minute detail of the nature of these singular rocks, the Author suspects, and very juftly in our opinion, that the columnar, as well as the other forms of this granitello, are to be looked upon as natural breaks or fissures, determined partly by the nature of its constituent parts, and partly by its respective fituation, or other particular circumstances. By these he understands a more or less fudden cooling of the whole mass; which he, like other Italian naturalists and observers, supo poses to have been in a state of fufion. He had observed in the iron founderies at Bergamo, that masses of cast 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 in. ner parts appearing as it were, fibrous, ftriated, and crystallized; whereas the more external parts are simply granulated, and in less determined forms.

We remember to have read a nearly similar hypothesis on the origin of the columnar Balaltes *, which, since 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 aflent, because it is established upon facts and analogy. If the whole mass of granitello in Monte Roslo had been in fusion, and cooled at once, its inner parts alone muft appear to be a group of columns; which not being the case, the Author very judiciously doubts, whether Mr. Strange's hypothefis is admiffible, suppoling that the whole mass had undergone a local ignition and alteration in the same place where we fee it at present; and he is of opinion, that it was accumulated by fuccessive volcanic eruptions : which however the Author should have more carefully proved than by bare affertion; for he could not be ignorant, that homogeneous masses 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 satisfied with his assertion concerning the pa. sallelopiped crystals in the mass of the granitello, which he is positive in declaring to be adventitious pre-existing bodies in the same form we see them, before they were wrapt up in the molten granitello or lava mass. Meflrs. Ferber, Raspe, and Sir William Hamilton, had looked upon different species of hirl crystallizations, which are found in the Vesuvian and other lavas, not as having pre-existed, but as having been produced in their cooling and congealing' masses. We must refer to their publica. tions *, where they have specified those particular thiri kinds, and the reasons and grounds of their hypothefis. As far we re

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

member, member, they never asserted that the granitello of Monte Rolo and the Vesuvian lavas are of the same kind; or, in particular, that the striated parallelopiped crystals of Monte Rosso ought to be Tanked amongst their volcanic shirls. Yet Dr. Gualandris charges them with that affertion, and boldly denies his affent to their hypothesis on the formation of other fhirl kinds, though it is well supported by some facts they have given, and by the analogy of certain crystallizations, which are undeniably produced in the melting pots of the glasshouses. They were first observed by Mr. Keir, who described them in a dissertation, which, about two years ago, was presented to the Royal Society. Dr. Gualandris had an opportunity of seeing many samples of chereglass crystallizations in Mr. Greville's noble collection in London. He himself agrees, that “to all appearances they are certainly produced in the mass of glass when in a state of fusion; yet he will not allow the above naturalists to draw from them any analogical conclusions in favour of their volcanic crystallizations : because, fays be, the glass, which served as a menstruum in the crystallization of these figured bodies was homogenecus, and in a perfect state of fufion; whereas the lavas are rather hetorogeneous mixtures, scarce affected by the fire, and at most a thick paste, not at all reduced to any tolerable degree of liquidity, which the crystallization absolutely requires, and which to suppose, he declares to be against reason and common sense.” 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 crystallizations produced in it prove it to conviction ; that the mixture of lavas evidently is and must be very various; that the posible degree of their liquidity, which bas not yet been ascertained, is and must be in proportion to the degree of heat, which they may undergo; and chat we cannot take upon us to agree with Dr. Gualandris in his round affertions, which he himself acknowledges to be unsupported by chemical experiments.

We are better and fully satisfied with his very sensible re. marks on the difference of granite and granitello; and we congratulate the university of Padua on having produced fo valuable and learned an observer of nature.

• See Ferber's Mineralopical Travels to Italy, Raspe's Account of some Gersan Volcanos, and Sir William Hamilton's Campi Phlegræi,

Rar-pe.

ART.

ART. XV. Differtatio Pbyfrologico-Medica Inauguralis, De Menfibus ex Materia

quadam peculiari, Ovariis Societa, oriundis, A Physiologico-Me. dical Inaugural Differtation, on the Origin of the Menses, from a certain peculiar matter, secreted by the Ovaries. By Phoebus Hetzerus Themmen, of Groningen. 8vo. Leyden. 1781. T HE ingenious Author of this thesis, after propofing and

1 attempting to overthrow the common theories of the menstrual Aux, offers his own, which is, that a certain mat. ter fecreted by the ovaries, and periodically descending into the uterus, is the cause, as well of the venereal appetite, as of the menses. The fanguineous discharge therefore, according to him, is only a kind of concomitant circumstance, and not elfentially necessary 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 hypothesis ; which, probably will share the fate of many an ingenious conjecture, not thoroughly compatible with the phenomena of nature.

A.

CORRESPONDENCE. R. D. observing in the Review for November last, a note from oor correspondent-Nimrod, observes, that Peter Beckford, Erg; of Scapleton, Dorsetshire, son of Juliois or Julianus Beckford, and nephew of the late celebrated Alderman of that oame, the professed 20. chor of Tboughts on Hunting, is not the Mr. Beckford to whom Mr. Brydone addresses his letters, nor are they relations.

He is fon-in-law of the present 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 West of England. R. D, expreffes his concern chat we should have been milled, by a cor. respondent, in a description of the real or professed author of Thoughts on Huntiog, and he remarks that there is anorber book on the fame subject, (but rather on hare hunring) 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 says he, you think proper to ascer. tain the author, by distinguishing him from William Beckford, Efq; of Ellex, you may do Mr. Peier Beckford a favour, by ascribing to him the honour of this first essay on this subject in English, and ob

lige a confant reader.” *!* Widfall speedily give some account of the book on Hunting, al.

luded to in ihe latter part of the foregoing letter. It is entitled Efsays on Hunting.' Southampton, printed,

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