legs, it crawls about in queft of food; and its movements are, in fome fpecies, remarkably quick. Its head is armed with teeth or pincers, by which it eats the leaves of plants or other kinds of food. In this ftate it is abfolutely deprived of fex, and confequently of the power of multiplication. Its blood moves from the tail towards the head. It refpires either by ftigmata or fmall apertures placed on each fide of its body, or by one or feveral tubes fituated on its pofterior part, which have the resemblance of so many tails.'

In the fecond period the caterpillar throws off its skin, and exhibits its internal parts, covered with a foft tranfparent membrane. In this state it is called nymph. If to these is added a common cruftaceous covering, it receives the name of chryfalis. The infect is now deprived of the power of motion, and remains torpid. The circulation of the blood takes an oppofite course, proceeding from the head to the tail. The organs of refpiration are transferred from the pofterior part of the body to the anterior. Before this ftate of imbecility comes on, the grovelling caterpillar is led by instinct to fecure a peaceful

retreat:

Some, as the filk-worm and many others, fpin filken webs or cods round their bodies, which completely difguife the animal form. Others leave the plants upon which they formerly fed, and hide themselves in little cells which they make in the earth. The rattailed worm abandons the water upon the approach of its metamorphofis, retires under the earth, where it is changed into a chrysalis, and, after a certain time, burfts from its feemingly inanimate condition, and appears in the form of a winged infect.-Some caterpillars, when about to change into the chryfalis ftate, cover their bodies with a mixture of earth and of filk, and conceal themselves in the loofe foil. Others incruft themselves with a filky or glutinous matter, which they push out from their mouths, without fpinning it into threads. Others retire into the holes of walls, or of decayed trees. Others fufpend themselves to the twigs of trees, or to other elevated bodies, with their heads undermott. Some attach themselves to walls, with their heads higher than their bodies, but in various inclinations; others choose a horizontal pofition. Some fix themselves by a gluten, and spin a rope round their middle to prevent them from falling.

The chryfalis is commonly fmooth and fhining. Its colour is papilionaceous, and fometimes it has the rich appearance of gold. Hence the Greek name of chryfalis and the Latin of aurelia. But the infect is deftined to undergo another metamorphofis. It affumes the diftinction of fex, it is invested with wings, and burfts from its tomb in the gaudy form of a fly. Mr. Smellie relates some of the more remarkable inftances of transformation:

1

The whole moth kind, as well as the filk-worm, immediately before their transformation into the chryfalis ftate, cover their bodies with a cod or clue of filk, though the nature of the filk, and their mode of fpinning be very different. The cods of the filk-worm are compofed of pure filk. Their figure is generally oval, which neceffarily refults from that of the animal's body upon which they are moulded. When fpinning, they twilt their bodies into the form of an S. The cod is produced by numerous convolutions and zigzags of the fame thread. The filk is fpun by an inftrument fituated near the mouth of the infect. The filky matter, before it is manufactured by the spinning inftrument, appears under the form of a gum almost liquid, which is contained in two large refervoirs contorted like the inteftines of larger animals, and which terminate at the spinning inftrument by two parallel and flender conduits. Each conduit furnishes matter for one thread. The fpinning inftrument, as it is evident when viewed by the microscope, unites the two threads into one.'

It appears that the fly previously exifts, encafed in the caterpillar, and that the parts are gradually developed, and the external coverings fucceffively detached, till the infect acquires its perfect form. Moft butterflies void a large quantity of a redcoloured excrement. Hence the showers of blood which have, at different times, terrified the populace by dreadful portents.Every organised being is deftined to undergo a transformation. The world is conftantly in motion; every thing advances to its maturity, or haftens to its decline. Hence the great mystery of Nature, that eternal circle of production and abhorred decay.

FOREIGN

LITERATURE.

ART. XI. Efais, ou Recueil de Mémoires fur plufieurs Points de Minéralogie, &c.

ART. XI. Efays, or a Collection of Memoirs upon feveral Subjects of Mineralogy; with a Defcription of the Pieces depofited in the Cabinet of the King of France; to which are added a chemical Analysis of thofe most interefling, and the Topography of Moscow, written after a Journey through the northern Parts of Europe, undertaken at the Defire of Government. By M. Macquart, Member of the Royal Society of Medicine, &c. &c. 8vo. 580 Pages, with Cuts. Paris, 1789.

SINCE a tafte for chemistry has for fome years paft almost

univerfally prevailed, and given birth to a number of important as well as ufeful difcoveries, the curious have been induced to extend their researches to every thing relating to that noble science. On this account the knowledge of minerals was

never

never carried to fuch a degree of perfection as it has attained at prefent among all the polished nations of Europe; and governments have never been fo fully fenfible that this branch of human industry, which furnishes fociety and the arts with fo many valuable and agreeable objects, deferves to be encouraged; efpecially as it must require long and laborious efforts to obtain a thorough acquaintance with it. For this purpose the observations of ingenious travellers must be compared, new ones must be made, and the different mineral productions of every acceffible latitude must be examined with the utmost care and minuteness. Those who vifit foreign countries are fufficiently attentive to what concerns the animal and vegetable kingdom; but they generally neglect thofe immenfe treafures which are concealed in the bowels of the earth. Senfible of this deficiency feveral enlightened fovereigns have lately engaged learned men to travel through their territories in order to examine their mineral productions; and indeed it must be acknowledged that fuch enterprises do more honour to nations as well as princes than conquests purchased at the expence of much blood and treasure.

For half a century an opinion has prevailed that the mineral productions of Ruffia deferve the attention of learned naturalists in general, and of mineralogists in particular, more than those of any other country in Europe. For this reafon the French government, which feems lately to have beftowed much attention upon every thing that concerns mines, engaged M. Macquart, in the year 1783, to make a tour through the northern Countries to collect fpecimens, and to examine every object that could tend to throw any farther light upon the mineralogy of that part of the globe. This commiffion M. Macquart appears to have executed with equal ability and diligence; and the interesting work now before us is the refult of his observations and researches.

The first memoir of this volume, which may be faid to confift of eight, though they are divided into different branches, refpects a fingular change in the gypfums of Poland, which are converted into chalcedony. As a proof of this phenomenon M. Macquart tells us that M. de Carozi, director-general of the mines of Poland, among many curious objects in his collection fhewed him feveral pieces of gypfum which he affred him were abfolutely converted into chalcedony; others in which the metamorphofis appeared to be confiderably advanced, and fome that exhibited only the firft elements of its formation.

In the fecond memoir he defcribes the celebrated falt mine of Wieliczka in Poland. This mine has already been described by Our countryman Coxe in his Travels through Poland; but as M. Macquart feems to have examined it more minutely, we

Ff4

Aatter

flatter ourselves that our readers will not be displeased to see his account of it here almoft at full length.

After examining,' fays he, as far as circumstances would permit, the environs of Cracaw towards the north, I was defirous of feeing on the fouthern fide one of the richest and most curious mines to be found in the whole world; I mean the famous falt mines of Wieliczka. When these mines belonged to the King of Poland ftrangers and travellers could procure accefs to them with the greatest facility; but fince they have paffed into new hands, they cannot be vifited without great difficulty. To procure a plan of them is impoffible; and thofe who have the direction of them are even afraid of permitting people to examine the different ftrata of falt for any length of time. They must not take any notes respecting what they have feen; and their prohibitions are fo ridiculous that the miners are exprefsly forbidden to fuffer the leaft fpecimen of the salt to be carried away. The lofs of this mine, which is more valuable than the richest mines of gold or filver, was one of the greatest that the Poles could fuftain. The prefent king, who is as much diftinguished by his extenfive knowledge in the arts and fciences as by his humanity and affability, in order to gratify his ardent defire of being useful to his subjects, has expended confiderable fums in endeavouring to discover fome veins of this rock falt on the other fide of Cracaw. I do not know whether his attempts have been attended with fuccefs; but if it be true that the more thefe veins extend towards the north the deeper they are from the furface of the earth, it will not appear aftonishing that great difficulties ftill occur.

When you have obtained permiffion to defcend into this mine, after putting on a miner's frock you are tied to a large rope, which is fastened to a wheel turned by a horse at its mouth. At certain diftances in this rope there are knots containing pieces of wood thrust through them, upon which people are feated, by means of a girth that paffes below their thighs, and another behind their back, and when they lay hold of the rope with their hands they are then in perfect fecurity.

This method cannot be better compared than to that employed by tilers when they fufpend themselves from the roofs of houfes. Three pieces of wood generally pafs through each knot; and, according to the number of perfons, feveral companies are formed, who defcend all together at the same time: the number fometimes is from twelve to fifteen. Some of the miners who go down with you hold fticks in their hands to prevent you from being dashed against the fides of the pit; but, notwithstanding this precaution, you cannot help being at first

frightened,

frightened, when you confider that your existence, for a few minutes, depends entirely on the strength of the rope.

In this manner you defcend through an opening eight feet fquare, which extends to the depth of two hundred: the fides of it are lined with large planks of oak, in order to prevent the falling in of the fand, which is found in great abundance above a layer of clay, more or less coloured; it is very friable, and interfected with calcareous fpar: at a certain depth are found feveral laminæ of very thin and blackish calcareous stone.

The spaces cut out in the falt from top to bottom may be confidered as fo many ftories. When you arrive at the first ftory, by means of the rope to which you are fufpended, you find different galleries, one of which conducts to a beautiful wooden ftaircafe, fupported by props, fuch as is not to be found in any

other mine whatever.

In this firft ftory there is a piece of architecture cut out in the folid falt, and forming a complete chapel, which attracts the notice of all ftrangers. It is dedicated to St. Anthony, and may be about thirty feet in length, twenty-four in breadth, and eighteen in height. Not only the steps leading to the altar, but the altar itself, the candlesticks, and the twilted pillars which fupport the roof, are of falt; and every thing that ferves to ornament the chapel, fuch as the pulpit, the crucifix, and the ftatues of the Virgin and St. Anthony, are of the fame subftance. On the left, as you enter, there is a ftatue as large as life, and compofed of very tranfparent falt, which reprefents Sigifmund, King of Poland. Befides this there are two other chapels, in which mass is celebrated on ftated days of the year, in remembrance of certain phenomena that formerly happened in this mine, which has made fome hiftorians affert that there was once a city in these fubterranean regions. It is the more aftonishing that tales of this kind fhould be propagated, as the depth of the first ftory is only two hundred feet from the furface, and there still remain nine hundred to the deepest part of the `mine.

The greater part of the galleries in this mine are fo beautiful that they refemble long ftraight ftreets; and I have feen fome of them cut through mafies of the pureft falt, which reflected with the greatest vivacity the light of the flambeaux that our guides carried to conduct us. With regard to the pretended houfes, they are only fquare chambers, cut out in the falt on each fide of the galleries, and fhut with doors made of common deal, in which the miners lock up their utenfils every evening before they depart.

The deeper one penetrates into these mines the falt is found purer and in greater abundance: neither fulphur, bitumen, nor

coal,