o'clock in the morning, when no electricity can be difcovered till noon, or about two in the afternoon, when it is at its maximum. This obfervation is the more remarkable, as it flows that it is not the local temperature which determines the ufual routine of the electrical changes; for, as the temperature is nearly that of the winter in the plains, if it were owing to that cause the maximum fhould occur, as in the winter, in the morning, and again in the evening. The strongest electricity, which they obferved, feparated the balls only three lines eight tenths, which fhows that the intenfity of electricity decreases as the den. fity of the air leffens. The electricity in ftorms was as ftrong as in the plains, and then was fometimes negative: in general, however, it was pofitive. Our author did not employ M. Vol ta's method of increafing the quantity of electricity, or render ing it more confpicuous. By fixing, at the point of the conductor, a fmall taper, or a fulphured thread, which is to be lighted at the moment of the experiment, the electricity is conducted to the electrometer, fought after by the flame and fmoke.' M. Sauffure wanted only a comparative ftate of the air and its electricity.

Fogs occafionally arofe from the condenfation of the air again the cold neighbouring hills; but there were evidently changes in drynefs and moisture, independent of heat and cold. The period of the greatest drynefs was, as in the plains, about four in the afternoon, and of the greatest moisture, between eight and nine at night, or four and five in the morning. During the night, in good weather, the hygrometer always went on towards dry. The greatest drynefs, which prevailed in the air during their continuance on the mountain, was at four in the morning, when the heat was fomewhat below the freezing point. The hygrometer was at 52.5, and the rest of the night proceeded towards moisture. At the other times, when the air was extraordinarily dry, it was wet at Chamouni, but not proportionally fo. The abfolute quantity of moisture feemed to be lefs at the Col de Geant than at Chamouni.

The next object of M. Sauffure's attention is the proportional evaporation of water; and, from his experiments, it follows, that a degree of difference in the heat produces an effect three times as great as a degree of drynefs; and one degree of drynefs is equal to about nine degrees of the hygrometer. On the plain the proportion is different. On the whole, about one third diminution in the denfity of the air renders the quantity of evaporation double; and this accounts in a great degree for the drynefs and the cracking of the fkin in those who refide on high mountains, which would be more confpicuous if the perfpiration was not also increased. This effect is, however, peculiar to air in a state of tranquillity, for, when in motion, the fhock of the denfe air compenfates for the power acquired by its greater rarity; and our author found that, on the mountains as on the plains, when the air is moving at the rate of thirty-fix or

thirty-feven feet in a fecond, its power is three times greater than when in a state of tranquillity, and nearly equal in both fituations. The fuperior power of dry air alfo, in increafing evaporation, is lefs confpicuous when the air is in motion.

The evaporation of ether was not fo much affected by the rarefaction of the air as might have been fuppofed: it feemed to be flower on the mountain than it was on the plain, probably impeded by accidental circumstances. Our author's experi ments are not, however, conclufive: one impediment to accuracy he mentions; and this arifes from the cold produced, and the confequent precipitation of water from the neighbouring air, which mixes with the ether. In the experiments on the cold produced by the ather the effect of the rarefaction is more confpicuous, though not regular. The moisture of the air prevented its evaporation and the confequent effect. It is probable, however, that the rarefaction of the air does not increase the evaporation of æther fo much as it does that of water, perhaps because the æther has a more powerful tendency to form an elastic vapour than water, without the affistance of air.

The account of the Journey of M. Sauffure to Mount Rose is only in part published: we shall notice fhortly what we have hitherto received of it. Mount Rofe (Monte Rofa), is the principal hill of the fouthern boundary of the chain of the Alps, as Mount Blanc rifss over the northern boundary of the fame chain. This mountain may be feen from all the plains of Piedmont and Lombardy, from Turin, from Padua, from Milan, and even far beyond is. Yet it has never been described: by many travellers it has not been mentioned; and from those in whole works it occurs, no very exact information can be obtained our author was eager to examine it, and began his journey with his fon in July of laft year: his tour contains fome fingular circumstances. In his way he visited the noble collection of baron Erlach, at Laufaane, where he found not on. ly a beautiful collection of the ores of Saxony and other countries, but the most complete collection, which exifts, of the minerals of Switzerland, and particularly the crystallized feld fpaths and fchorls, and the tourmalines of St. Gothard. From Laufanne they proceeded to Vevay, to Martigny, to Sierre, and to Viege. In the last stage they croffed the torrent of Millgrabe, one of those rapid and transitory streams which fall from the Alps with inconceivable violence, and pafs away with the ftorm which contributed to their fury. The ftream of Millgrabe had hollowed the ground to a great depth, and covered its banks with a large quantity of yellowifh earth. All this had been done the day before, and it was already almoft dry. A quarter of a league beyond it, if the traveller turns to the right, he fees a kind of funnel, compofed of high mountains, whose bare fides are furrowed by the ftreams which fupply the torrent, and are covered with earth of the fame colour.

M. Sauffure then defcribes the paffage over the Simpione, iz French

French the Simplon, which fome authors have raised to the rank of a faint, ftyling it Saintomb: its greatest elevation is 1029 toifes. This part our countryman, Mr. Coxe, fcarcely faw, and we shall transcribe M. Sauffure's bold and animated defcription of the paffage.

"On the fide of Switzerland the traveller paffes through beautiful forefts, under the moft magnificent fhades, watered, not by torrents, but by rills, as gentle as they are limpid. The fide of Italy prefears, on the contrary, rocks the most abrupt and the most terrible; like enormous walls, fharpened to a point, and fo near, that a fingle block of granite rolled from the mountain is fufpended between the walls of the valley, and ferves as a bridge from one bank to the other. Ar fome distance the torrent precipitates itself into an abyfs, with fuch violence, that the drops broken and raised by the air, which feparates the particles, mount with impetuofity as the steam of an enormous cauldron; they are coloured by the rays of the fun, and appear a mixture of flame and fmoke. But it requires a good head to receive from fuch fcenes a pleafure unalloyed by fear, for the road, or rather the path, often projects over a dreadful precipice, and is fcarcely four feet wide, without any parapet. In many parts it is worked out of the rock; and there is one place where the rock is pierced at the edge of a projecting part, and appears like a ring iufpended in the air. The traveller who fees it at a diftance, for the first time, can fcarcely believe that he muft pafs on horfeback through this ring. The route terminates at Lake Major, and is the most frequented pafs for transporting corn and wine, which is done on mules. As it is the route alfo of the courier of Milan, it is kept up with the greatest care. Yet it is not eafy to traverfe on a mule, "cornices" fo ftrait, fo high, and paved with granite polished by travelling: it is indeed better to walk, particularly down the hills; but, whatever tafte the traveller may have for these savage beauties, he fe Is a real fatisfaction on coming out of these defiles, and ecing the country open near Dovedro. There the mountains feparate on the eaft, and form an ample girdle, which inclofes an amphitheatre of vines and chestnut-trees; a delicious mixture of a beautiful verdure and handsome buildings.'

On the fide of Switzerland the rock is calcareous, mixed with more or lefs of glimmer: the ftrata vertical, or nearly vertical. On the other fide are either the common foliated rocks, compofed of quartz and mica, or veined granites: they are generally horizontal, or inclined at most from thirty to forty degrees. On the northern fide of the road, about a league and a quarter from Simplon, is a block of white calcareous stone, confufedly cryftallized, and confequently a marble of the kind called faline. It is fix feet thick, naturally dividing in laminæ, of from feven to eight lines, and is bounded on each fide by a foliated vitrefcent rock of quartz and mica. If this iaft is a pri

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mitive

mitive rock, our author thinks the calcareous must be allo pri mitive, as the vitrefcent rock rests on it. The diftin&tion, however, added in the note, appears of importance, and is truly new. We fhall tranferibe it.

The calcareous, fecondary rocks, or thofe which have been formed fubfequent to the revolution, at the conclusion of which the fea was inhabited by fish, and abounded with fhells, are almost always covered with grits, with breccia, and puddingftones; in other words, with the remains of the rocks, broken to pieces in the revolution, Thefe remains, interpofed be tween the ftrata of primitive rocks and thofe of the fecondary ftones, form the transitions which I have often observed, and particularly at the bottom of Buct (Voyages, fect. 594). The calcareous primitives, on the coutrary, or thofe which have exitted previous to this revolution, are not diftinguithed by fuch tranfitions, or they are tranfitions of another kind.'

Domo d'Offula is the next principal town which they mention, and they foon arrive at Lake Major, and then follow the right bank of the Toccia, to go three-fourths of a league far ther to Pié de Mulera, where they find the first effects of the gold mines of Macugnaga; the great church and the Palazzo Tefloni being built by means of the gold drawn from the mines, From the middle of the bridge leading to Vanzon, a village in the road to the mines, they fee Mount Rofe, which arifes as majestically as Mount Blanc, feen from Salenche. This mountain has the advantage of appearing furrounded by the beautiful verdure of the narrow and deep valley of Anzal ca, which, like the frame of a picture, fets off the whiteness of the fnow and the ice. This exquifitely beautiful valley, where the verdure and the trees are equally luxuriant, is bounded by the approaching hills, which meet, except in one point, where the river Lanza patles out, The nature of the rocks refembles that of the valley of Martigny (Voyages, fect. 1047, &c.) The fituation of the ftrata is nearly vertical; the direction of their planes nearly that of the valley.

At a little diftance from Vanfon is a tranfverfe rock, which inclofes as it were the mines. Near the bridge of Vando is a magnificent block of granite, in the middle of which was a group of large hexagonal cryftals of black fchorl, fet in a mixture of white feld fpath and filvery mica, The fituation of the village of Macugnaga is faid to be very beautiful; but the inhabitants were not hofpitable. Habitations were only wanting; for the inhabitants, and even the curate, live on milk and rye-bread, made fix months in advance, and which can be cut only by a hatchet. Our travellers provifions were brought from Vanzon,

The mineral of gold is found in the continuation of the bafe of Mount Rofe: it is compofed of a veined granite or a foliated rock of feld fpar, mica, and quartz. I he rata are generally horizontal, or a little inclined, and the gold is found in all the varieties of this granite, but generally in the fofter kinds and

thofe

thofe of the finest grain. The matrix of gold is a yellow fulphureous pyrites. Gold alfo occurs in the carious hollows of the quartz, mixed with a ruft of iron, which appears to be the refiduum of decompofed pyrites. The auriferous pyrites are often crystallized in cubes; but thefe are the poorelt: thofe whofe grain is finer are not much richer; and the most valuable are thofe where the cryftallization appears to have been rapid, fo that little of the metal has efcaped, and these pyrites appear in the form of large fcales. The threads are offen vertical, but the threads affect no particular direction. They fometimes cross each other, and the groups of auriferous pyrites, in the interfection, are large and rich. The expence is effimate ed at 46800 livres per annum, and the income at 59800 livres. M. Testoni, whofe mines are the fubject of this estimate, clears therefore about 1300 livres, about 540l. per annum. It is fuppofed, however, that on account of the proportion paid to the lord of the foil and to the king, the profits are diminished; and, on the other hand, it is laid that the richer veins, which appeared to be the more fuperficial ones, are exhausted. In all gold mines the profit has been generally exaggerated. The mode of extracting the metal is not peculiar, nor very fcientific; but it feems fufficiently exact.

Co

The high pics of Mount Rofe are inacceffible, it feems, from the fide of Macugnaga; but one of thefe of a lefler height is acceffible on this fide. On account of the fnow with which it was conftantly covered, it is ftyled Pizze Blanco-the White Pic: our travellers fet out on the 30th of July, and encamped on the Alp of Pedriolo, for the Alps retain their original Celtic fignification in this country, as well as in the German part of Switzerland: it fignifies the pafturage of the mountain.' After encamping on the fe meadows, they began to measure the highest pics of Mount Rofe, and found the highest 2430 toifes above the level of the fea, and the lowest 2398; the higheft is, therefore, within twenty toifes of the height of Mount Blanc. We paffed the night (fays M. Sauffure) under our tent, in a fituation truly delicious. We were encamped in a meadow, vered with the clofe turf of the highest Alps, enamelled with the most beautiful flowers. Thefe meadows were terminated by the Glaciers and the pics of Mount Rofe, the magnificent outlines of whofe higheft cliffs were feen to advantage, against the azure vault of heaven. Near to our tents flowed a rill of the frefheft and clearest water. On the other fide was a cavern, under whofe fhelter we burned the rhododendron, the only wood which grows at this height, and whofe fire ferved to warm our foup, and to defend us against the harp freshness of the evening. The night was magnificent; and I was too fond of contemplating it, for from the cold I fel: fome inconvenience, which delayed my journey a little the next morning. This journey was indeed very painful; we paffed with fome difficulty over the hanging precipices of broken rocks, which were very steep; we occafionally

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