houses.-Disgraceful complaints, or the diseases of females, were considered as offending the sacerdotal dignity.-Physicians, thus confined within such narrow limits, would have enjoyed a great portion of leisure, if they had not had recourse to a species of quackery. Under the semblance of piety, they offered their advice for sale in the church of Notre Dame. Some patients went thither in person; and such as were unable to go sent their urine or faces to have their complaints pointed out. Those who were more anxious sent a detail of symptoms in writing; while others, by means of some persons who had witnessed their sufferings, applied to those charitable physicians who piously sold their advice. Thus the priests were consulted in temples like the antient oracles, and exercised the same functions as the priests of Apollo and Esculapius. There were also, however, some lay physicians, as Lanfranc informs us, who undertook the treatment of every complaint, and who went to visit such patients as were confined to bed: but they were not attached to the university; and to laymen alone was that privilege allowed. Afterward, the university imposed no other law on physicians than celibacy; since the year 1305 it has been no longer necessary, for the purpose of being adopted by the university, to embrace the ecclesiastical state; and the faculty of physic could give to married physicians a dispensation to practise their profession." It has been already said that the Jews were, at this time, the principal physicians in Europe; and so much were they in repute, as even to be employed in the service of popes, and in that of the Moorish kings of Spain. - Medicine might be considered as their national profession, but the monks disputed the exercise of it with them; and, in the end, got possession of it, in spite of the decrees of the Council of Trent. The third period in the History of Medicine comprizes the fifteenth and sixteenth centuries, when Europe began to emerge from that state of barbarism in which it had for so many ages been involved. The fourth, and last, is principally confined to the seventeenth century, which was celebrated for the production of many very distinguished physicians.-In this division of the work, notices are given of Van Helmont, Prosper Alpinus, Becher, Forestus, Sanctorius, Descartes, Sydenham, Morton, Mead, Friend, Hoffman, Boerhaave, Stahl, Baglivi, Riverius, and Etmuller. In the account of the practice of Sydenham, the author mistakes the opinion of that great man, when he represents him as erring in his supposition that pleuritis and peripneumonia essentially differ from each other. Sydenham's words on this subject are," Quam (speaking of peripneumonia) ego ejusdem plane indolis cum pleuritide esse arbitror, atque ab illa in eo tantum differre, quod peripneumonia pulmones universalius adficiat. Quin et utrique morbo pari omnino methodo medemur, venæsectione scilicet, præ cæteris, et medicamentis refrigerantibus." Hoffman is passed over too slightly: but a very ample space is allotted to a detail and examination of the doctrines and practice practice of Boerhaave. Considering, however, the present state of medical opinion, the author seems to us to have taken unnecessary pains to disprove the principles of that celebrated physician. ART. VII. Nouveau Dictionnaire d'Histoire Naturelle, &c. i. e. A [Article concluded from the last Appendix.] TH It is the common fate of compilements to assume a fair appearance at the outset, and to diminish in interest as they advance but the reverse is the case with the dictionary now under our consideration, of which the latter end is better than the beginning. Among many judicious and excellent articles contained in the 16th volume, those relative to the Eye, Pink, Egg, Goose, Bird, Olive-tree, Orange tree, Ortslan, and Bread, are fraught with accurate and substantial information. M. Parmentier's contributions are particularly valuable, as they are immediately connected with practical and economical details; so that the farmer, the cook, and the householder may reap considerable benefit from consulting them. His remarks, for example, on the best methods of preserving eggs will be found a wholesome comment on the warm statements of the otherwise correct and cautious Reaumur. The latter seems to have supposed that the suppression of evaporation was alone necessary to insure the soundness of an egg for any length of time; without adverting to the disorganization, and consequent corruption, induced by carriage of the commodity. A single jerk may break the delicate vascular ramifications which connect the embryo with the membrane of the yolk, and thus occasion putrefaction. The commodity, therefore, should be transported on a carriage which is suspended on springs, so as to avoid jolting. It is also recommended to boil eggs hard, on the day on which they are laid, and to put them up in a cool place, where they may safely lie for three or four months. In this state, it is obvious, they will easily bear carriage.-A mixture, composed of a bushel of quick lime, two pounds of salt, and eight ounces of cream of tartar, with a quantity of water sufficient to admit the complete Yell, complete immersion of eggs, has been known to preserve them fresh for two years.-Sed paulo MAJORA canemus. The combining causes of a thunder-storm are at least very ingeniously stated by M. Libes; and they are the more deserving of our attention, because they involve a new theory of the Aurora Borealis. That we may succeed in our inquiry, it is of consequence to remark, 1. That the torrid zone is the favourite theatre of thunderstorms. They are unknown in the regions near the poles. It never thunders in Greenland, nor in Hudson's Bay. (Mussembroek, tom. iii. p. 414.) In the temperate zones, thunder storms are more frequent and more violent, in proportion as we approach the tropics; and in the latitude of between 40 and 50 degrees, summer is the usual season of thunder-storms, which are always preceded by a suffocating heat.. These facts, confirmed by a long series of accurate, observations, warrant the conclusion that the days, on which thunder-storms occur, are marked by a considerable disengagement of oxygen and hydrogen gases, occasioned by the decomposition of water; and, as the atmospheric strata, which we inhabit, contain only oxygen and azotic gases, blended in a certain proportion, we must believe that the hydrogen gas escapes into the upper regions of the atmosphere, where it occupies a place appropriate to its specific weight. The oxygen gas probably serves it as a surrounding vehicle; and the levity of the small bubbles, formed by the gascous substances, with the additional aid of violent winds, (the usual fore-runners of thunder-storms,) determines their elevation in the atmosphere. 2. During thunder, the electrometer apprizes us of an excess of the electric fluid in the upper strata of the atmosphere; at the same time that a great variety of substances, of which the terrestrial globe and its atmospheric envelope are composed, eagerly re-demand a portion of their natural fluid, which has probably served to volatilize certain bodies, and to impart to them that levity which ascer tains their elevation in the atmosphere. Hence thunder presages the restoration of the equilibrium of the electric fluid, or, in other words, its passage from the superior atmospheric strata into the different terrestrial bodies which solicit its return. In this passage, which is accomplished with inconceivable rapidity, the electric fluid, in different points of its course, encounters, mixtures of oxygen and hydrogen gases. They immediately combine; and their combination gives rise to violent explosions, and to a mass of water proportioned to the quantity of aeriform fluids which contributed to produce it. Who would refuse to the concurrence of the oxygen and hydrogen gases, and of the electric spark, the power of producing the rain which accompanies the flashes of lightning and the noise of thunder? The ingredients of the atmosphere are little else than air and water dissolved in that aeriforin fluid. Hence we may ascribe a thunder shower to the circumstance of the atmospheric air parting with the water which it held in solution, or the combination of the bases of the oxygen and hydrogen gases by the electric spark. 6 · In In our attempts to explain a phænomenon, if several insulated causes may produce an effect, we cannot discover to which of these causes the effect is owing, without investigating each of them apart. Agreeably to this principle, we should ask, whether it be probable that water held in solution by the air of the atmosphere should collect in sensible masses, so as to generate rain exactly at the mo ment when the thunder-storm is brewing? It is incumbent on those who maintain this opinion, to explain why thunder showers are sudden and instantaneous; why they fail not till the storm has taken place; why they end immediately with it; and, finally, why they are so favourable to vegetation. These circumstances, combined, attest the influence of the electric fluid on the formation of this sort of rain; which, in course, we can only attribute to the reciprocal union of oxygen gas, hydrogen gas, and the electric spark. The thunder shower commences only when the three elements of its composition happen to meet in the atmosphere; and the absence of any one of those three elements always predicts its termination. When, by the intervention of the electric fluid, the bases of the oxygen and hydrogen gases intimately unite, in order to form a thunder shower, this union causes the violent explosions which con stitute thunder. Our naturo-electricians believed that they could imitate the latter by means of their machines; and they long confounded it with a few paltry cracklings-with those faint explosions which are produced by the discharge of the Leyden phial. This sort of illusion has passed away; and it is now generally admitted that we cannot imitate, in our apparatus-rooms, the formidable noise of thunder, except by transmitting the electric spark through a suc cession of Volta's pistols, which contain a duly proportioned mixture of the oxygen and hydrogen gases. This explanation of the meteor in question appears to me the more satisfactory, because it is connected with that of the Aurora Borealis, a remarkable phænomenon (Article AURORA BOREALIS) which Patrin has described with that elegant simplicity which characterizes his pen. I shall here confine myself to a summary explanation. 1. If the electric spark be made to pass through a mixture of azotic and oxygen gases, the result is nitric acid, nitrous acid, or nitrous gas, according to the proportion which exists between the oxygen and azotic gases, which compose the mixture. 2. The nitric acid, when it comes in contact with the solar light, assumes more colour and volatility. This observation of Scheele suggested to me the following experiment: I placed a receiver on a large plate containing nitric acid, which I exposed to the sun. In a few minutes, the acid became coloured, and the receiver was filled with red and volatile vapours, which continued for a long time, and emitted a light like that of the Aurora Borealis. 3. It is well known that, in the flasks containing nitrous acid, a reddish and volatile vapour, which never condenses, is seen above the acid. 4. Nitrous gas, in contact with atmospheric air, always exhales ruddy vapours, which fly off into the atmosphere. 5. The solar heat has very little influence in the polar regions. A moment's reflection on the principles which I have just stated, and of which the existence is unquestioned, suffices to prove, 1. That the production of hydrogen gas in the polar regions can hardly be perceptible. 2. That the higher regions of the polar atmosphere scarcely contain any hydrogen gas. 3. That, as often as the equilibrium of the electric fluid is restored in the polar atmosphere, this fluid, in its passage, can come in contact only with a mixture of azotic and oxygen gases. 4. That the electric spark should fix and combine the gaseous substances. 5. That the result of this combination should be a production of nitric acid, nitrous acid, or nitrous gas, according to the proportion which exists between the oxygen and azotic gases which compose that mixture. 6. That the production of nitric acid, of nitrous acid, or of nitrous gas, should give rise to red and volatile vapours, which ascend in the atmosphere, and there constitute the meteor known by the name of Aurora Borealis.' In answer to the question, Why the same appearance is not observable in the torrid and temperate zones, M. Libes remarks that the activity and duration of the solar heat, in warm countries, occasion a considerable disengagement of the hydrogen gas; which, in consequence of its levity, escapes into the higher regions of the atmosphere. The electric fluid therefore, in every attempt to regain its equilibrium, encounters a twofold mixture of gases; namely, of the azotic and oxygen, and of the latter and hydrogen. Now we know, by experience, that the electric spark manifests a greater affinity to the second mixture; and that the combination is always accompanied by a loud explosion, and a production of water proportioned to the quantity of aeriform fluids on which the electric spark exercises its activity. Hence the frequency of thunder, lightning, and sudden and heavy rains, in the hot latitudes; and hence the absence of streamers in the same latitudes. The common supposition, which ascribes the Aurora Borealis to a great quantity of the electric fluid accumulated in the polar regions, and animated by movements and colours peculiar to itself, will not abide the test of observation and experiment. It is now an acknowleged fact that the electrical fluid gives out no radiant light, unless it be put in motion in vacuo. If, then, we assert that its simple movement is the cause of the northern lights, the appearance must have its origin beyond the limits of the earth's atmosphere: but several reasons concur to prove that this is not the case. This meteor frequently assumes the appearance of an ordinary cloud; it may sometimes be observed at one place and not at another, though the distance between the two places be not considerable; it is occasionally accompanied by a crackling or rustling noise, which is heard on the earth's surface; and it sometimes preserves, for a fixed time, the |