with thofe of the winds, which account for its little variation between the tropics, where the winds are conftant; the greater extent of its range in winter than in fummer, and the relation of its variations to the different temperatures, a relation not quite exact, as it is influenced by many different caufes. But befides thefe changes, there appears to be a diurnal periodical variation in this intrument, which Father Cotte thinks is fufficiently evident in the barometography of M. Changeux; and the abbe Chiminello thought that he perceived a friking relation between the variations of this inftrument and the pofitions of the moon, which would include a relation alfo between its motions and the tides. Thefe coincidences are not, however, yet established, In a table added to this memoir, containing obfervations made on the barometer three times a day, in fixty cities, for a number of fucceeding years, we find that the mercury has always a tendency to rife in the morning till towards the evening; that this tendency is more diftinguishable from two to nine o'clock in the evening, fince the mercury is then highest, The elevation of the evening appears to differ fourtwelfths from that of two o'clock, which differs only one-twelfth from that of the morning. The author remarks that, in fome climates, the lowest period is at two in the afternoon. We have not been inattentive to the difpute refpecting the hair-hygrometer, but have been able to collect little fatisfactory information, From fome obfervations we have had occafion to anake, we think there is great variety in the hygrometrical affinity of the hair of different perfons; and this difference, we fufpect, extends to every kind of animal fibre. While we are fpeaking of philofophical inftruments, we are led to recollect the new pneumatic machine (it muft not be called an air pump), of M. Cazeler, We find it difficult to give an account of it in any other words than his own, and might at last find the task not very eafy to render it intelligible. It confifts in filling a large balloon of water, purged of air by boiling, and exhaufting again the water, while the air is prevented from returning by a valve. This operation is repeated three times, and then leaves only 347 part of the former air. With mercury the process is more eafy, but pretty expenfive. The abbe Her vieu propofes fome improvements on the operation, but for both we fhall refer to the Journal de Phyfique for May and July of the last year. The arcometer, or as we call it the hydrometer, is also an inftrument at prefent of fome importance in arts and manufactures, as it shows the denfity of liquors by a very simple and eafy experiment. The inftrument differs according to the li quors to be examined; and that, which we shall first mention, is the areometer of M. Vallet, director of the manufactory of acids at Javel. The defects of the ufual inftruments, he obferves, when employed for acids and fpirit of wine, are owing to the principle followed for the divifion of the fcales. It has been been ufual to fix on the point, at which the areometer properly ballanced, finks in pure diftilled water, as the zero of the fcale; and to determine the other limit by the point at which it funk in a folution of ten ounces of very pure dry fea falt, in go ounces of water. This space was divided for acid into ten equal parts, which commonly amounted to 40 or 45 degrees. Each degree marked it was not confidered that, as acids were more concentrated, the degrees fhould have been gradually less, for in mixing acids with water, while the latter is added in arithmetical progreffion, the denfity of the former diminishes in a geometrical. As the areometer was formerly graduated, it tood in the muriatic acid at 22 degrees, and in the nitrous at 47; but, for the vitriolic, it was neceffary to have another inftrument, whose scale began from the point where the first ended, and was continued to 70 degrees in the vitriolic acid of the greatest degree of concentration, this areometer stood at 66. It is evident therefore that thefe fcales did not give the proportion of water either mixed with acids or with spirit. Our author, in the improved inftrument, marks the extremes at the parts of the stem, to which the areometer finks in pure water and pure acid. His firft divifion, which he marks 4, is with 4 ounces of acid and 12 of water: his middle term with equal parts, and his third divifion with 12 ounces of acid and 4 of water. His degrees therefore point out ounces of water or acid in different parts of the fcale. The areometer, for fpirit of wine, is made in a fimilar way, only that the degrees, inftead of ounces of the acids, are English gills ( of a pint) of fpirit. Our author's eafy geometrical method of constructing thefe inftruments must be feen from the plate, which accompa nies the memoir. M. Dutrone, we find, ufes the common areometer, that of Baume, for ascertaining the denfity of melaffes; and we should not have mentioned him in this place but to obferve, that the quantities of fugar, &c. diffolved, do not proceed in the fame progreffion as the degrees of the inftrument. His tables afford a fufficient foundation for correcting it in this refpect. The greatest difference that he ever found in the richness of the melaffes was within the points of 5 and 14 of the common instru ment, containing, in a quintal, 9 pounds, 3 ounces, and 34 grains, and 25 pounds 11 ounces, 6 drachms 8 grains refpectively. Mr. Kichardfon's faccharometer, ufed in brewing, is constructed on a better principle, and is a more useful inftrument. As our chief object in this fketch is to defcribe philofophical inftruments, it is enough to mention M. Pagot des Charmes' machine for polishing looking-glaffes, or copper for engravers, and the fame author's new method of engraving plates and cy linders to ftamp gauze. We shall now turn our attention to the application of the inftruments we have particularly noticed, and introduce our accounts with the continuation and conclufion of M. Sauffure's journey. After After having determined the pofition of Mount Rofe, and examined its internal structure, our travellers endeavoured to afcertain the external structure. They departed from Macugnaga on the fourth of Auguft, defcended the vale of Anzafca, to Ponte Grande, a fhort league below Vanzon; from whence they paffed Lanza, and flept at Banio, a large village, elevat ed 338 toifes, on the vigil of the feast of our Lady of the Snows, a proper patronefs for an Alpine town. A ferpentine path, in a forest of vaft and ancient chestnut-trees, perfectly illuminated; with numerous oratories occafionally scattered, fimply but nobly decorated, led to the chapel, and impreffed on the foul the fentiments of refpect and veneration, which the ornaments of worship ought always to infpire.' They next afcended to the top of the Egna, at the height of 104 toifes, and again defcend ed to Carcofazo. In this route they furrounded the mountain, obferving the mine of copper at Allagna, which confists of a yellow pyrites, diffeminated in a ftratum of fix or feven feet in thickness, which finks from 25 to 30 degrees from the east to the fouth-west, and furrounded by parallel ftrata of a rock, confifting of mica, iron ore, and white feld-fpar. It was the mountain of Rothhorn where M. Sauffure stopped to examine the external appearances of Mount Rofe, at the height of 1506 toifes above the level of the fea. The circumference of the crown feemed more magnificent on the outfide than within. All the pics which formed this crown occupied on their horizon a space of more than 60 degrees, from whence at that distance the diameter must have been gooo toifes, or double of the internal diameter. This fhows that the interior circle is not formed of a fingle range of mountains, and that there are many without which are not feen from the infide. Mount Rofe is not therefore an ifolated mountain, but a central mals, fupported by feven or eight vaft chains, which are higher the nearer they are to the centre, and mix with the general mountain, or become ornaments to its crown. Some of these external ornaments feem to have been broken; fo that the chain, of which their fituation formed the extremity, feems to terminate abruptly, before it reaches the principal mountain. The other chains approach more nearly to it. All thefe mountains are foliard rocks of different kinds. The immenfe concourse of thefe high fummits prefented to the most careful examination neither vertical ftrata nor granites in mafs. All the chains which reach to Mount Rofe are compofed of ftrata which fall gently from its fide, making an angle of 30 or 35 degrees with the horizon; fo that Mount Rofe, which is inacceffible on the infide, feems to be practicable from without. All these declining ftrata are covered with maffes of fnow, which reach fo far down as fome rocks that feem of eafy accefs, and will pro bably conduct a traveller fafely to the highest pics. The danger only arifes from the ftate of the fnow, from unfufpected ravines, In In the intervals of thefe inclining mountains are numerous and beautiful glaciers; the moft remarkable glacier is that from which the river Lys flows, and gives the name to the valley that it waters. Three of thefe glaciers unite and reach almoft to the paftures of the Trinity at Greffony, and, from thefe, the river appears to burst out. Between two of the fnowy precipices which hang over thefe glaciers, there is a very elevated neck of land filled with fnow. There was an ancient tradition that it led to a beautiful valley, and that the paffage was now fhut up by new glaciers. Some adventurous youths fet out on the difcovery, and faw a valley, whofe exiftence was afterwards denied, and it became the subject of a curious controverfy, whether fuch a valley had ever teen feen. On examining the different bearings, and making the fullest enquiry, M. Sauffure concludes that they really did fee a beautiful valley, but it was the Alps of Pedrilio, which he paffed in his route to the interior circle of the mountain. The reality of is valley, and the juftnefs of their conjecture, they leave however for future examination. In their return from Mount Rofe, they paffed the glacier of Mount Carvin, clevated 1550 toifes, When they faw the glacier it was covered with a thick fog, and they defcended to Le Breuil, as the page in that fate of the air was dangerous; and, from this village, it was tafer to cross the glacier even in the best weather. When they arrived on it they found it covered with fnow: but there were no ravines nor even the usual marks of them, furcows in the fnow. The afcent was fo eafy that they could ride on their mules, but, as the fnow became deeper, they were obliged to dilimount and even unload them. They no longer funk in the fnow, but they experienced all the breathleffnefs and debility which men feel on fuch elevated fleeps: they even uttered a kind of plaintive cry, which is not heard even during the fevereft fatigues, for they were on higher ground than mules were ever employed in Europe, being 1736 toifes above the fea. This fpot alfo affords another fingularity; for, on the highest point, is a redoubt constructed of loofe ftones with regular embrafures for large mufquets. It was built three centuries ago, as a defence against the inhabitants of Valais. This is probably the highest fortress on this globe, and its fituation is in many refpects beautiful. The wind fweeps the fnow away from the ridge during the fummer; and the eastern fommit, where the author's tent was pitched, called St. Theodule, was adorned with the diapenfia Helvetica, and the racunculus glacialis. It was undoubtedly a more favourable fpot for the meteorological obfervations than the Col de Geant, and very little lower. The profpect from this fpot is beautiful, and the mountain appears in a very advantageous light from it; but the most beautiful object is the high and bold fumnit of Mount Cervin, which rifes to an enormous height, in the form of a triangular obelisk, which feems to have been fhaped haped by a chiffel. Our author means to examine it more par ticularly, but it is inacceffible, being too steep to allow the fnow to reft on it. In this fpot alfo there were no granites in mafs, no vertical ftrata. The height of St. Theodule, and the rocks which our author vifited to the north above this point, were compofed of alternate ftrata, a little inclined, of fteatite, calcareous stone, and quartz. Among the ftones which fell from Mount Cervin, our author found only veined granites, and foliated rocks of quartz and mica; but the variety of colours in this natural obelifk fhows, that it probably contains fome other kinds. Its ftrata are not distinct, though they are fo in the other parts of the chain, which forms as it were the fhoulders of this enor mous Giant. Our author foon returned, and the mules feemed particularly cager to efcape from thefe icy regions. Nothing very particular occurred in his journey to Geneva, from whence he had been ablent thirty-feven days. He returned the twentieth of August. M. de Sauffure, in the continuation of his account, recapitulates the remarkable properties of Mount Rofe, which we need not follow; but we may add, from the conclufion, a few words refpecting the inhabitants of this country and their manners. The villages round the mountain are chiefly German, but the inhabitants now speak French and Italian. The origin of thefe Germans is unknown: they probably were inhabitants of the Upper Valais, who, on traverting the Alps, faw that the fummits of thefe valleys were not inhabited, and fixed on them, while the more effeminate inhabitants of Italy had not courage to lead their flocks or to vifit thefe apparently inhofpitable regions. The barren and ungrateful foil fcarcely furnifhes them the conveniencies of life, and the men foon leave it, as the knowledge of three languages, which they may acquire in their infancy, fits them for travelling. The women remain almost wholly charged with the labours of agriculture. They alfo carry the burthens, and travel with great dexterity, avoiding the dangerous fpots, thus loaded, in places inaccef fible to beafts. Their ftrength, their diligence, and their integrity are equally remarkable. They will carry a burthen fufficient to load two mules, and which a man can fcarcely lift, nor does this exceffive labour leffen their gaiety and fpirit. They accompanied our author; and, as they had no burthens, they ran on laughing, fpringing and leaping from the point of one rock to another, finging in the fhade till our travellers overtook them, when they again fet off with their ufual velocity and gaiety. Sobriety, the ufual attendant of industry, distinguishes alfo thefe mountaineers. Their rye-bread, we have faid, is eaten only fix months after it is baked: they foften it in whey or butter-milk, and it makes their principal food; checfe, and a 7 little |