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they would contract the streets, as the walls made with bricks of this kind must be very thick. In the country they were al lowed with proper precautions. They were made with different mixtures of lime, fand, clay, chalk, pumice-ftone, and ftraw; were two, three, or even four feet in length: the lar geft, were more than a foot thick, but they were often intermixed with bricks of a fmaller fize. Such bricks are eaûly made; and, though Vitruvius directs that they should be dried for two years before they be ufed, this can occafion no particular delay, fince the ftone of Italy, when first raifed, is fo foft, as to require an equal time for hardening. In the bricks they fometimes mixed ftraw and powdered pumice-ftone, which rendered them fo light as to float in water. Our author has mifinterpreted this paffage in Pliny, when he fays that they were not penetrated by the water. Such bricks would now be highly useful for vaults and flooring. But one precaution, either in making bricks of this kind, or imitating the Roman cement, fhould not be neglected, viz. beating the materials very carefully with iron mallets.

Though the duration of these unburnt bricks was, according to Pliny, eternal, if the perpendicular was ftrictly preferved, yet, about the time of Auguftus, they were generally burnt, and mixed with chains of hewn and rough ftone, fo as to facrifice in a great measure time and money to appearance. The fame clay was moulded by the Roman architects into many different forms, particularly vafes, of which they form ed arches much lighter and more durable than ours. Various works of this conftruction remain, and we are told by M. Vol ney, that the fame practice ftill prevails at Aleppo. The French artifts have lately attempted to imitate this ftructure, but with what fuccefs we know not.

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The Romans prepared clay alfo for cornices and roofs. At Pompeia, many of the houfes are encircled with bold cornices, made of terra cotta, caft in large pieces. Thefe cornices are ernamented with defigns and arabefques; and our author thinks, both from their appearance and ufe, that they are what Vitruvius means by his 'lorica teftacea,' designed to carry water beyond the walls. Another method of employing clay was in coating the pillars as with a ftucco, and the capital anfwered the purpose of a cornice to carry off the rain. The burnt bricks, moulded into a variety of forms, were used alfo as a foundation for the Roman roads, where the bottom was clayey, and flints could not eafily be procured. The forms are infinitely various, feemingly from accident or fancy, for the bricks were not finished with any care: they were thrown in confufedly, with the cinders and other rubbish of the fur

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nace. Foundations of this kind have been difcovered in different places: an inftance of it occurred at Marfal in Loraine. The bas reliefs of the houses were alfo conftructed of burned clay, and were ceconomical ornaments, as they coft only the price of the defign and the mould, which might be repeatedly ufed. Some of thefe ornaments are fo hard, as to strike fire with fteel; many are preferved by cardinal Albani in his beau tiful villa; fome of which Winckelman has defcribed in his • Monumenti Antichi inediti.'

On many of these bricks, the names of the legions and of the workmen are infcribed; and, when we examine these, we have much reafon to complain of the little folidity of our own manufacture. In general, this is owing to too low a degree of heat, to the pyritous mixtures which occasion fufion, and the heterogeneous matters, which the workmen are afraid of converting into glass. This can only be remedied by a more careful choice of the materials, and exciting the emulation of artists, by obliging them to impress their names on the brick.

Genera Infe&orum Linnai & Fabricii iconibus, illuftrata a Joanne Jacobi Roemer. 419. Veloduri Helvetiorum.

WE

E wish to announce this work, though it cannot furnish any very extenfive details or difquifitions: we mention. it chiefly on account of its utility, and the merit of its execution. The entomological fyftem of Linnæus is well known: it is fingularly neat and comprehenfive; and if this place would admit of fuch difcuffions, we think we could fhow that it might be more easily extended than altered. The outline of Linnæus' fyftem is taken from the wings; and infects are divided into three great claffes, according as they have four, two, or are wholly without wings: the two left are undivided, under the terms dyptera and aptera. The firft is fubdivided into thofe which have the upper wings of a different ftructure from the under, and thofe which have all the wings fimilar. The cruftaceæ are those which have the fuperior wings more hard and brittle, feparated by a ftrait line when clofed: the order is styled in the fyftematic language, coleoptera, the eleuterata of Fabricius. The femi cruftaceæ are thofe in which the upper part of the wing, next the joint, only is brittle, called hemiptera, the ulonata and ryngota of Fabricius. Thofe which have all the wings of a fimilar structure, are the infects with fealed wings, lepidoptera, the gloffata of Linnæus; and thofe which have membranous wings, are divided into those which have ftings; and those which have none, the europtera and hymen. optera. It must be allowed that these claffes are fometimes APP. VOL. IV. NEW ARR.

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too artificial, but this was no reason for changing the whole! a better one is, that the genera are not always well characterifed, and the fpecies often improperly combined.

Fabricius was a pupil of Linnæus, and learned from his maf ter to view nature with an accurate, comprehenfive eye. He faw the entomological fabric was externally elegant and fafcis nating, but within irregular, confufed, and erroneous. He ftudied fyftem in the botanical works of his preceptor, and transferred the rules to that of infects, rejecting any very great anxiety to make the claffes and orders perfectly natural, and contented with diftinguifhing the fpecics clearly, afcertaining fo near as the ftate of fcience would admit, fpecies from varieties, and carefully connecting the fpecific diftinctions with the generic character. His Philofophia Entomologica, a work published in 1778, is an excellent proof of the clearness of his views, and the fevere accuracy of his difcrimination. The confequence has been, that the fyftem of Fabricius has been gradually extending: he has added a mantiffa of new discover ed animals, and of more correct defcriptions or definitions, and, thus giving his fyftem the advantage of keeping pace with new discoveries, has contributed to fix it on as firm foundation as the fimilar additions of the difciples of the Linnæan fchool have already eftablifhed Linnæus' fyftem of botany. We fhall, for the fake of more general readers, add the outfine of Fabricius' work.

The claffes are eight in number; the characters taken from the figure, proportion, and fituation of every part of the month; chiefly from thofe parts employed in devouring the food. Of the claffes, four are taken from the appearances of the jaw, and four from the defcription of the mouth. The jaw is either naked and unconnected, eleuterata; covered with the galca obtufe, ulonata; united with the lip, fyniftata; or the lower jaw is deficient, agonata. The mouth is either furnifhed with maxilla and feelers, the lower jaw frequently hooked; unogata; furnished with feelers and a fpiral tongue, gloffata; with a roftrum, its fheath articulated, ryngota; furnifhed with a fucker, or fyphon, its fheath not articulated, antiliata.

While there is fo great diverfity in thefe fyftems, and that of Linnæus is by no means forgotten, it is an object of im portance to compare them, and to examine the correfponding genera, particularly as a very important entomological work, published in Germany by Sulzer, is arranged wholly according to the fyftem of the Swede. For the affiftance of the reader, the genera of Linnæus and Fabricius-are inferted with the effential generic characters; thofe of each naturalift following cach other according

according to their refpective systems, and fome fpecies are added, illustrated with plates, executed with great accuracy, diftinctnefs, and elegance. The plates refer to species; confequently the defcription of each author is illuftrated by it, and the fyftems are, in fome measure, contrafted. At the end is a plate, in which the parts of the mouth, and inftruments employed by the animal in devouring its food, on which each order depends, are delineated; but we must add, neither very accurately nor diftinctly; though, on the whole, the work deferves confiderable approbation, and will be highly useful to ftudents in entomology. In no place has Fabricius explained his terms with fufficient accuracy, nor has our author, in the additional plate, greatly affifted the learner. It is necessary to explain the only technical word ufed in this Article, galca: the term is applied to the upper-lip, when in the fhape of a

fhield.

Idee generale de la Siberie & de fes Habitans. Par M. Patrin, de plufieurs Academies.

THIS memoir, published fome time fince in the Journal de

la Phyfique, we have often alluded to, and promised to give fome account of it. Our knowledge of this country is not inconfiderable; but it is confined to works which feldom meet the eye of the English reader, who is almost wholly limited by what Dr. Bell has obferved in this part of Afia, and what Mr. Tooke has collected from the narratives of the Ruffian travellers. The defire of knowing, fays M. Patrin, that part of Afia which is called Siberia, and of bringing to my country fome ufeful obfervations and interefting productions, made me fupport for eight years the rigours of its forests, to ftudy nature in thefe regions fo near the pole.'

This vaft country, fo little known in happier climates, contains many rare plants and minerals, of which we have had already fome fpecimens from the attentive and fcientific induftry of Gmelin, Pallas, and his companions. M. Patrin has added to these imported riches, and we fall follow him in his more general and more particular accounts.

Siberia, it is well known, is feparated from the Ruffian empire by a long chain of mountains, extending from north to fouth, which are in reality the most natural boundaries interpofed between Europe and Afia: they are ftyled the Rural Mountains, and are cinphatically called by the Ruffians, the Girdle of the Earth.' Towards the fouth, Siberia is bounded by numerous groups of mountains, extending from west to eaft, fo far as the confines of China, which are diftinguished by different names in their different parts, as Altai, Saiann,

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&c.

&c. On the north is the icy fea, or the ftrait which feparates Europe from America. The rivers are fome of the largest in the world, the Irtifh, the Ob, the Yeniffei, the Angara, and the Lena. The north of Afia, from weft to eaft, may be diyided, our author tells us, into fix diftricts. First, the fpace between the rural mountains to the Yeniffei, which is moun tainous, or confifting of marthy forests, immenfe plains, or deferts, whofe foil is impregnated, not with natron, as the defarts of Egypt, but with a vitriolated lime or magnefia: the only cultivated spots are the neighbourhood of the rivers, where Tobolík, Pomfk, and other lefs confiderable cities are fituated. The fecond diftrict is from the Yeniflei to the lake Baikal, a fpace of about 300 leagues, in which the country is varied by hills ftretching from the fouthern chain. In this region are firft difcovered the peculiar productions of Afia, and it contains the capital of oriental Siberia, Irkoutz, at a little diftance from Baikal, which deferves the name of a fea from its fize, as it is 120 leagues long and 25 leagues mean width. To the east of the Baikal is the third country, called Daourie: it is wholly alpine and volcanic, with numerous hills of decompofed lava, whofe cavities are filled with chalcedony. The volcanos are fo ancient that their craters are obliterated, though there are fome more modern, but inconfiderable ones, particularly in the hills which are in the direction of the river Ouda. The part which belongs to Ruffia, extends northerly to the gulph of Kamtfchatka, and to the fouth fo far as the confluence of the Chilea and the Argreenn, which form the river Amour: the rest is fubject to the emperor of China. The fourth divifion is Kamtfchatka, which we have formerly defcribed when we followed M. Lef feps in his travels".

This country is inhabited by Ruffians and Tartars; but the number, in an extent of 1500 leagues in length by 600 in width, fcarcely exceeds 1,200,000 fouls, which amounts only to twelve perfons in nine fquare leagues. The Ruffians refemble entirely those of Mofcow: the fame manners, the fame drefs, language, and houfes: the nefts of fwallows are not more alike, as if the influence of an abfolute government had checked every kind of emulation, and reduced man to his most general principle, imitation. The Siberian is lefs a flave than a Ruffian, for he depends only on the monarch, though the fubordinate tyrants are often more formidable than the empero. In a free government, the Ruffian might appear with equal advantage, as in the military department, intelligent, active, reflecting, and endowed with a fpirit of calculation,

This work is printed in four volumes, 8vo, entitled Ruffia. See Crit. Rev. vols. xlix. li. and lvi.

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