Imágenes de páginas

The 28th and 29th plates exhibit Views of the Town of SanNicolo in the fame ifland, taken from different points of obfervation. In the explication of the 28th plate our Author makes farther observations on the island of Tenos, whose small extent of twelve miles in circuit is compenfated by its fertility, and which contains near twenty thousand inhabitants, difperfed in about fixty villages. It bore formerly the name of Ophiussa, from its being infefted with ferpents, and hence in Greece the viper is faid to have been called Tania. Its inhabitants are governed by their own magiftrates; no Turkish officer renews by his prefence the idea of their fervitude, and they only feel one day in the year that they are under the yoke of defpotifm.

The 30th plate represents the land and Town of Syra, formerly Syros. The traveller, fays M. DE CHOISEUL, who fails through the Archipelago, feels the most agreeable emotions in recalling to memory the great men, who once rendered these iflands famous, and make us ftill behold them with a certain fentiment of homage and respect. The image of Pythagoras arises to his fancy, when he arrives at Samos,-Lefbos recalls to him Alcæus and Sappho,-Ceos prefents to him Simonides the mafter, and Bacchylides the rival, of Pindar. He pays homage to the fhade of Hippocrates when he comes to Cos, and to that of Archilochus when he arrives at Paros. Syros had the honour of giving birth to Pherecides, one of the most ancient philofophers, and the mafter of Pythagoras.

In the 31ft plate we find a Plan of the Ifland of Delos. The ruins, fays our Author, with which Delos is covered, proves the veneration of the ancients for that ifle in a ftill more powerful manner than the Odes of Callimachus and Pindar. The fables, which ennobled the origin of Delos, excited the piety of the Greeks, who were always fond of the marvellous, to lavish on this ifland the richest oblations and prefents. The azylum of Latona, the place which gave birth to Apollo and Diana, could not but be honoured with a univerfal worship. All the hiftorical details that regard Delos, are comprehended here in a moft animated description of the feafts that were celebrated of old in that ifland. This defcription is the compofition of an anonymous Author, who detached it from a large work, and permitted M. DE CHOISEUL to infert it here. It is rather too poetical with respect to ftyle and imagery, but it has great merit as to erudition and eloquence, and will be read with pleafure by the lovers of claffical antiquity.

*For our accounts of the two former Numbers of this fplendid work, fee Appendixes to our 58th and 59th volumes.



Nouveaux Memoires de l'Academie Royale des Sciences et Belles Lettres. Annie 1776-avec l'Hiftoire,-New Memoirs of the Royal Academy of Sciences and Belles Lettres of Berlin for the Year 1776, with the Hiftory relative to that Year. Berlin. 4to. 1779. HISTORY OF THE ACADEMY.


HE firft thing we meet with in the hiftorical part of this volume (after some discourses on occafion of the reception of members, which we pafs over in filence) is a letter of DR. WILSON, of the Royal Society, to the Academy of Berlin, in which he communicates to that learned body his discovery of fome new properties of light. We have also here the opinions of fome of the principal Academicians concerning this discovery. Among these opinions, that of M. Beguelin is peculiarly interesting, and bears all the marks of that penetration, extensive knowledge, and amiable candour, that fo eminently diftinguish this excellent philofopher. This discovery, we fuppofe, is well known, as alfo the experiments by which it was made; it ftruck, indeed, the members of the Academy with great furprise, and appeared directly contrary, not only to the obfervations of Newton, but also to the known properties and nature of light. That the red or ubrific parts of a phlogifticated oyfter-fhell, or phofphorus, fhould exhibit a feeble and pale red after having been exposed to the red rays of the folar beam alone, and should, on the contrary, appear with a red several shades deeper and more lively, when exposed to the green rays only, and with a still more lively and brilliant red when expofed to the blue ones, seemed to M. Beguelin, incompatible with the theory of the immutability of the rays of light; and this ingenious academician makes several acute reflections on the subject, as alfo on the feries of experiments on the phosphori and their prifmatic colours, of which the learned Author made a prefent to the Academy.

This is followed by the obfervations of M. SULZER on a brass nail found in a quarry of lime-ftone near the port of Nice in Provence, and by the eulogies of the deceased Academicians, GUISCHARD (called Quintus Icilius), HEINIUS and KUSter. MEMOIRS.


Concerning Friction, confidered as diminishing Motion and oppofing it. By M. LAMBERT. Second Memoir.

Concerning the Powers of the Human Body. By the fame. Part firft. Thefe are confidered here as moving and accelerating powers; but both the extent of the piece, and the series of the reasoning, render this memoir incapable of abridgment.

Chymical Refearches concerning the Topaz of Saxony. By M. MARGRAFF. This ftone is found, in confiderable quantities, in Voigtland, about two miles from Averbach, in the crevices of a yery hard rock, where it is mixed with a kind of yellow marl


and with rock-cryftal. With refpect to its internal texture, it is compact, but foliated like the diamond; its form is prifmatic, and has four unequal angles; it is alfo hard, and has a vivid luftre. M. MARGRAFF, having obferved, that hard ftones, and more efpecially those which are placed in the clafs of precious ftones, are not compofed of homogeneous earths, but of earths of different kinds, thought proper to begin his researches on this fubject by examining the topaz by the means of diffolvents, and fubjecting it to the trial and operation of acids. In order to execute this defign, and to discover the different kinds of earth which enter into the compofition of the topaz, he chose the three acids of the mineral kingdom, thofe of vitriol, nitre, and falt, and having pulverized his topazės (a circumftance neceflary when hard ftones are to be fubjected to chymical operations) he began his experiments, which are here circumftantially related, are very curious, and fhew that the topaz contains a calcareous and an argillaceous earth.

An Inquiry into a Point of Phyfiology, relative to the State of the Pelvis or Bafon of Women, in the Circumftance of Child-birth. By M. DE FRANCHEVILLE. This fubject of inquiry is curious and important. The queftion is, whether or no, at the time of delivery, the Pelvis in lying-in women yields and is dilated in order to facilitate the paflage of the child? The greatest part of the medical faculty anfwer this question in the negative; feveral, however, are for the affirmative, in confequence of their own obfervations: from whence it is natural to conclude, that this dilatation does not actually take place in all women, but that it may happen, and that it has happened;-and this is what the learned academician propofes to prove, and has fully proved, in this memoir, both from the conftruction of the bason in wọ- · men, and from the teftimonies of the moft celebrated Anatomists and Physicians both of ancient and modern times.

Experiments on the Electrophorus, together with a Theory of that Inftrument. By M. ACHARD. The inftrument, here mentioned, is of late invention, and its fingular and unexpected effects have excited, in a peculiar manner, the attention of the obfervers of nature. The conftruction of this inftrument and the manner of ufing it, as alfo its preferving its electricity for a confiderable space of time, are well known. It was to discover the manner in which the electrophorus acts, and produces its effects, that M. ACHARD made the fixteen experiments related and described in this excellent memoir, and which do such honour to the fagacity and abilities of that celebrated naturalift. For an account of these experiments we must refer the Reader to the volume before us; but the conclufions and results deducible from them, and which M. ACHARD deduces from them in effect, with the cleareft evidence, are, ift, that it is not ne


*y ceffary,

ceffary, that the brass-plate fhould touch exactly and in all its furface the circular glass plate which is originally electric; for our Academician having placed horizontally a circular plate of glafs, a line and a half thick and a foot in diameter, upon a plate of tin, which touched the glafs only in a few places, the upper furface of the glafs being electrified by rubbing, produced all the effects of the electrophorus:-2dly, that the metallic plate, or the board of the electrophorus covered with tin-foil, is not effentially neceffary to the production of the effects which have been? obferved in that inftrument, and that when the electrophorus is deprived of it, it retains nevertheless all its properties:-3dly, that the property which this inftrument has of retaining its electricity longer when it is infulated by a fubftance, which acquires, by rubbing, an electricity contrary to that which is given by rubbing," to the electric plate, is not peculiar to the electrophorus, but is common to all fubftances which are originally electric:-4thly, that in order to draw fparks from a conductor, it is not neceflary that it fhould touch or communicate with the metal or tin-foil, that covers the inferior surface of the electrophorus, as fome affert; all that is required for this purpose is, that the conductor be touched by a body, which is adapted to tranfmit to it a portion of the electrical fluid :-5thly, that the electrophorus can never render the conductor electric, unless it be touched by a body, that is non-electric by itself:-6thly, that the electrophorus never electrifies the conductor, but fo far. as the latter receives or lofes a quantity of electrical fluid :-/ 7thly, that the conductor, as foon as it is placed on the electrophorus, acquires a fmall degree of electricity, which it lofes at the approach of a finger, and recovers the moment that it is taken away from the electrophorus:-8thly, that the electrophorus, whofe inferior metallic coating, or whofe conductor is electrified, produces the effects of the Leyden phial:-9thly, that to render the inftrument under confideration electric, it is not necessary to rub it directly; electricity by communication being fufficient for that purpose, as it produces the fame effect:/ Iothly, that the moment that the conductor is placed upon an electrophorus of fealing-wax, it acquires a weak pofitive electri city, and acquires a weak negative electricity when it is placed upon the fame inftrument made of glafs-thly, that if we touch the conductor, after having placed it on an electrophorus of fealing-wax or glafs, it lofes all its electricity:12thly, that when, after having placed the conductor on an electrophorus of fealing-wax, and touched it, we take it away from the inftrument, it acquires, the very moment it is lifted up, a pretty strong negative electricity; but when the electrophorus, employed in this experiment, is of glafs, the electricity of the conductor is pofitive.



[ocr errors]
[ocr errors]


[ocr errors]

The explication which this ingenious Academician gives of the effects of this celebrated inftrument, is recommendable for its fimplicity; his description of fome new electrophori, conftructed upon the principles which have been here afcertained by the most accurate experiments, is very curious, though fuccinct; but it would be difficult to render it perfpicuous to the Reader without the affiftance of the plates.

Concerning the Nature of the Earth, which is the Basis of the vegetable and animal Creation. By M. ACHARD. When any portion of animal or vegetable matter is fubjected to the com bined action of air and fire, there remains, after the intire dif perfion and evaporation of the volatile parts, a fixed refidue of a grey colour, which, by a calcination, continued for fome time longer, becomes intirely white. This refidue is a mixture of fixed alkali (united fometimes with other falts), and of the earth, from which the part of the vegetable or animal, that was burned, derived its folidity. In order to obtain this earth alone and fe parated from all other matter, nothing more is neceffary than to lixiviate the residue with diftilled water. By this procefs all the faline particles are removed, and the earth, that formed the bafis of the calcined vegetable or animal matter, remains alone in its moft perfect state of purity. This is the method that has been followed by our ingenious Academician. He gives us accordingly a circumftantial account of thirteen experiments, which he made in order to discover the earth that conftitutes the bafis of vegetables-but of thefe we can only specify the results. 1ft, the earth, already mentioned, diffolves, with effervefcence, in all acids:-2dly, it forms, with the marine and nitrous acids, falts per deliquium, that are not fufceptible of cryftallization:3dly, the marine acid adheres fo closely to the earth of vegetables, that the action of fire, alone, is not fufficient to separate them:

4thly, the marine falt, of which this earth is the bafis, is ful ceptible of decompofition by the vitriolic acid, and all the faline alkalis, except the caustic volatile alkali ;-the cafe is the fame with the nitrous falt which has vegetable earth for its bafis:5thly, heat alone is fufficient to carry off the nitrous acid that is united to the earth of vegetables:-6thly, this earth, faturated with the nitrous acid, acquires, by calcination, the property of fhining in the dark, provided it be previously expofed to the light:7thly, the vitriolic acid, in conjunction with this ve getable earth, forms a falt, which shoots into small cryftals, and requires a large quantity of water to diffolve it :-8thly, the action of fire alone is not fufficient to separate from the vitriolic falt (whofe bafis is vegetable earth) the acid, that is neceffary to the prefervation of its faline properties:-9thly, the vegetable earth decompounds cinnabar, by uniting itfelf with its fulphur, and difengaging the mercury, with which it was mineralized:












« AnteriorContinuar »