had not the preffure they were ufually accustomed to. We were all in a feverish ftate, as will be feen in the fequel. While I remained perfectly ftill, I experienced but little uneafinefs more than a flight oppreffion about my heart; but, on the smallest bodily exertion, or when I fixed my attention on any object for fome moments together, and particularly when I preffed my cheft in the act of stooping, I was obliged to reft and pant for two or three minutes. My guides were in a fimilar condition. We had no appetite; and our provifions, which were all frozen, were not well calculated to excite it: nor had we any inclination for wine or brandy, which increased our indifpofition, moit probably by accelerating the circulation of the blood. Nothing but fresh water relieved us; and much time and trouble were neceffary to procure this article, as we could have no other than melted fnow. I remained on the fummit till half past three; and though I did not lofe a fingle moment, I was not able to make all thofe experiments, in four hours and an half, which I have frequently done in lefs than three on the fea fide. However I made, with great exactnefs, thofe which were most effential. We returned much easier than I could have expected, fince, in defcending, we did not experience any bad effects from the compref fion of the thorax; our refpiration was not impeded, and we were not under the neceffity of refting, in order to recover our breath and ftrength. The road down to the first plain was, nevertheless, by no means agreeable, on account of the great declivity; and the fun, fhining fo bright on the tops of the precipices below us, made fo daz zling an appearance, that it required a good head to avoid growing giddy from the profpect. We pitched our tent again on the fnow, though we were more than four hundred yards below our last night's encampment. I was here convinced that it was the rarity of the air, and not the fatigue of the journey, that had incommoded us on the fummit of the mountain, otherwife we should not have found ourselves fo well, and fo able to attack our fupper with a good appetite. I could now alfo make my meteorological obfervations without any inconvenience. I am perfuaded that the indifpofition, in confequence of the rarity of the atmosphere, is different in different people. For my own part, I felt no inconvenience at the height of 4000 yards, or nearly two miles and a quarter; but I began to be much affected when I was higher in the atmosphere. The next day we found that the ice-valley which we had passed on our firft day's journey, had undergone a confiderable change, from the heat of the two preceding days, and that it was much more difficult to pafs than it had been in our afcent. We were obliged to go down a declivity of fnow, of no less than 50 degrees of inclination, in order to avoid a chafm which had happened during our expedi tion. We at length got down as low as the first eminence on the fide, about half after nine, and were perfectly happy to find our felves on a foundation which we were fure would not give way under our feet.' M. de Sauffure concludes this part of his account by informing us, that he and his party returned to the Priory by dinnertime,-all fafe and well. The The meteorological obfervations follow the hiftory of the journey they are abridged, but the Author promifes a full and cire cumftantial explanation of them in the 3d volume of his Travels. From the present narrative we learn, that the fummit of the mountain is a ridge, nearly horizontal, lying eaft and weft: the flope, at each extremity, is inclined from 28 to 30 degrees, the fouth fide between 15 and 20, and the north about 45 or 50. This ridge is fo narrow, as fcarcely to allow two people to walk abreaft, especially at the weft end, where it resembles the roof of a houfe. It is wholly covered with fnow; nor is any bare rock to be seen within 150 yards of the top. The furface of the snow is fcaly, and, in fome places, covered with an icy cruft, under which the fnow is dufty, and without confiftence. The highest rocks are all Granites; those on the east fide are mixed with Steatites; those on the south and the weft contain a large quantity of Schoerl, and a little lapis corneus. Some of them, especially thofe on the eaft, which are about 150 yards below the fummit, seem to have been lately fhivered with lightning. M. de Sauffure faw no animals on the mountain, except two butterflies, which he fuppofes must have been driven thither by the wind. Lichens are the only vegetables which are found on the more elevated parts of these mountains: the Silene acaulis, which grows in great quantities on the lower parts, disappears at the height of about two miles above the level of the sea. The obfervations of our philofophical adventurer on the barometer, are few: we hope, however, that those which he made on Mont-Blanc, and the corresponding ones made at Chamouni, and Geneva, will be fully related in his Travels. The labours of many philofophers, for these laft hundred years, have been directed toward a method of meafuring the height of mountains by barometrical obfervations. Dr. Halley, in the Philofophical Tranfactions of the Royal Society, has fhewn that the height of the mercurial column is always proportional to the density of the air, and that the logarithms of the denfity are reciprocally as the diftances from the furface of the earth. This doctrine fuppofed the denfity to be as the compreffion, and that the atmofphere was of an equal heat at every height. M. Caffini, and his affociates, when they were employed in measuring the meridian through France, found this theory not confiftent with experiments. The fubject engaged the attention of many philofophers, who have fince attempted to form a theory that thould correfpond with obfervations. M. de Luc has fucceeded better than any of his predeceffors in the inveftigation and folution of the problem; and has given an excellent rule for determining the height of a mountain, from four obfervations, viz. one of the barometer, and one of the thermometer, at the bottom, and one 144 166 one of each at the top, of the hill. By the experiments at Schehallien, the mountain attracted a plummet. Will not a mountain, therefore, attract the air? And will not the air round the top of a mountain, three miles high, be more dense than the air would be at the fame height above a plain? If this be the cafe, and there is every reafon to think that it is, then M. de Luc's rules will not be general. We formerly approved of these rules, and we do not even now fee any reason for difapproving them when they are confined to measure heights, independent of huge maffes of mountains; but the Schehallien experiments induce us to fufpect, that the quantity of matter in mountains muft affect the denfity of the air in their neighbourM. de Sauffure has given us the height of the barometer on the top of Mont-Blanc. Auguft 3. at noon, 16 inches, o lines, and of a line, French measure; (i.e. 16.181 EngFilb); and Reaumur's thermometer was 2.3 below the freezing point. M. Sennebier, at the fame time, obferved (at Geneva) the barometer 27 2 1888 (29.020 inches English); and the thermometer 22.6 above freezing. From thefe data he makes the height of Mont-Blanc 2218 toifes, or 14180 English feet (about 2 miles) according to M. de Luc's rule; and 2272 toifes, or 14525 English feet, according to M. Trembley's. To thefe heights 13 toifes, or 83 feet, the height of M. Sennebier's room above the Lake of Geneva, must be added, to give the height of the mountain above the level of the lake 14263 feet, according to M. de Luc, and 14608 feet, according to M Trembley. Sir George Shuckburgh made the height of Mont-Blanc, by trigonometrical measurement, 14429 feet above the lake, which is almoft the mean between the other two. The refult of the obfervations made at Chamouni, contemporary with those on Mont-Blanc, agrees ftill nearer with Sir George's measurement. The general mean refult makes the fummit of Mont-Blanc 2450 toiles, 15673 English feet, or three miles nearly, above the level of the fea. The hygrometrical obfervations fhewed the air on MontBlanc to be extremely dry. The refults of these experiments are fufpicious; and from the short account given of them in the work before us, we muft fufpend our opinion about them till we fee them farther illuftrated. They feem contrary to that excellent fyftem of meteorology + lately publifhed by M. de Luc, whofe arguments require to be refuted before we can affent to M. de Sauffure's affertion, when he fays, I fhall shortly make it appear, that M. de Luc's objections to this method [that used by * See Monthly Rev. vol. xlviii. p. 576.; vol. xlix. p. 579.; and vol. 1. p. 567. * See Reviews for April and Auguft last. M. de M. de Sauffure] of obtaining the measure of extreme humidity, are ill founded, and that his new hygrometer is a faulty and fallacious inftrument.' M. de Sauffure found by his electrometer, that the electricity of the air on the fummit of the mountain was pofitive. Water boiled at 68.993 degrees of a thermometer, which rises to 80 with the barometer 27 French inches high. The wind was north and extremely piercing on the fummit; but, fouthward of the ridge, the temperature of the air was agreeable. The experiments with lime water, and with the cauftic alkali, fhew that the air was mixed with atmofpheric acid, or fixed air. The quickness of the pulfe, after remaining four hours on the fummit, was, in one of the guides, 98; in the fervant, 112; and in M. de S. himself, 100 in a minute. At Chamouni they were 49, 60, and 72, refpectively. The effect of the rarefied air on the human body, is little noticed by M. de Sauffure among his other obfervations. The internal air would most probably fwell the body univerfally. This circumftance is not mentioned. The quickness and difficulty of breathing, must be attributed to the dilatation of the air contained in the cavity of the thorax, between the lungs and the pleura: this dilated air, the external compreffion being nearly half, would prefs the lungs together, and also impede the action of the diaphragm, and other muscles of refpiration it would alfo prefs the heart, and a greater exertion would confequently be required in that vifcus to expel the blood; whence the increased quickness of the pulse. No mention is made of its fulness or strength. From the foregoing account, M. de Sauffure feems to have made few difcoveries. The narrative of the journey is entertaining; and though the difficulties and dangers attending it would diffuade many people from vifiting those dreary regions, yet our philofopher promifes to reafcend the mountain, and favour the public with farther observations in that elevated fituation. We wish him fuccefs in his labours, and hope that he will, after his fecond journey, be able to relate, in a more fatisfactory manner, the various phenomena which his limited time on the fummit of Mont-Blanc prevented him from attending to, in the manner he wished. As Mont-Blanc is confpicuous at a vaft diftance, we should recommend it to philofophers who go thither, to make several astronomical and geographical obfervations, especially to afcertain its latitude and longitude-to find the refraction of the atmosphere-to take the angles fubtended by different remarkable objects, and the angles which those objects make with the meridian-to meafure the length of a pendulum-and many more, which muft prefent themselves to a diligent obferver. ART. ART. IV. Ger. Nicolai Heerkens Groningani Aves Frifica; i. e. The Birds of Friedland, by Ger. Nic. Heerkens. of Groningen. 8vo. pp. 298. Rotterdam. 1787. HEERKENS here defcribes, in Latin verfe, ten dif M. ferent birds, viz. the lark, the crofs-bill, the magpye, the fwallow, the goofe, the crefted wren, the quail, the ftarling, the thrufh, and the black-bird. The Author informs us, in his preface, that his fituation in the country afforded him ample opportunities of obferving feveral of the indigenous birds, and his love of the Mufes induced him to record his obfervations in Latin poetry. He appears to have read Ovid with attention, to have feen the beauties of that poet in a proper light, and, in many inftances, to have happily imitated his juftly admired bard. The following extract is part of the introduction to his poem on the lark: • Prima avium noftris dicetur alauda libellis, Quodque licet multum de frigore, deque malignis Nec placet ulla magis, quam quæ fuper æthera fummum Poftque dies medios audita meffor alauda Ad falcem rediit & grave ruris opus.' The Author proceeds to defcribe their marriage ceremonies, the manner of building their nefts, the tutelage and education of their young, &c. In fome parts of his poems, M. Heerkens enters largely into fubjects which have been much controverted among naturalifts. He fpeaks in pofitive terms of the torpid ftate of certain birds during the winter. Of the fwallow he fays: Conditur ante hiemem, femeftri obnoxia fomno, Res |