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our ladder without apprehension such of the chasms as were exposed to view; and, sometimes stopping in the middle of the ladder, looked down in safety upon an abyss which baffled the reach of vision, and from which the sound of the masses of ice that we repeatedly let fall in no instance ascended to the ear. In some places we were obliged to cut footsteps with our hatchet; yet, on the whole, the difficulties were far from great; for in two hours and a half we had passed the glaciere. We now, with more ease, and much more expedition, pursued. our way, having only snow to cross, and in two hours arrived at a hut which had been erected in the year 1786 by the order, and at the expense, of M. de Saussure. The hut was situated on the eastern side of a rock which had all the appearance of being rotten with age, and which in fact was in a state of such complete decay, that, on my return the next evening, I saw scattered on the snow many tons of its fragments, which had fallen in my absence; but the ruin was not on the side on which the hut was built. Immediately on our arrival, which was at five in the afternoon, the guides began to empty the hut of its snow; and at seven we sat down to eat; but our stomachs had little relish for food, and felt a particular distaste for wine and spirits. Water, which we obtained by melting snow in a kettle, was the only palatable drink. Some of the guides complained of a heavy disheartening sickness; and my Swiss servant, who had accompanied me at his own request, was seized with excessive vomiting, and the

pains of the severest headach. But from these complaints, which apparently arose from the extreme lightness of the air in those elevated regions, I myself and some of the guides were free, except. as before observed, that we had little appetite for food, and a strong aversion to the taste of spirituous liquors. We now prepared for rest; on which two of the guides, preferring the open air, threw themselves down at the entrance of the hut, and slept upon the rock. I too was desirous of sleep; but my thoughts were troubled with the apprehension that, although I had now completed one half of the road, the vapours might collect on the summit of the mountain, and frustrate all my hopes Or if at any time the rest I wished for came, my repose was soon disturbed by the noise of the masses of snow which were loosened by the wind from the heights around me, and which, accumulating in bulk as they rolled, tumbled at length from the precipices into the vales below, and produced upon the ear the effect of redoubled bursts of thunder. At two o'clock I threw aside my blankets, and went out of the hut to observe the appearance of the heavens. The stars shone with a lustre that far exceeded the brightness which they exhibit when seen from the usual level; and had so little tremor in their light, as to leave no doubt on my mind that, if viewed from the summit of the mountain, they would have appeared as fixed points. How improved in those altitudes would be the aids which the telescope gives to vision; indeed, the clearness of the air was

such

such as led me to think that Jupiter's satellites might be distinguished by the naked eye; and had he not been in the neighbourhood of the moon, I might possibly have succeeded. He continued distinctly visible for several hours after the sun was risen, and did not wholly disappear till almost eight. At the time I rose, my thermometer, which was on Fahrenheit's scale, and which I had hung on the side of the rock without the hut, was 8° below the freezing point. Impatient to proceed, and having ordered a large quantity of snow to be melted, I filled a small cask with water for my own use, and at three o'clock we left the hut. Our route was across the snow; but the chasms which the ice beneath had formed, though less numerous than those that we had passed on the preceding day, embarrassed our ascent. One in particular had opened so much in the few days that intervened between M. de Saussure's expedition and our own, as for the time to bar the hope of any further progress; but at length, after having wandered with much anxiety along its bank, I found a place which I hoped the ladder was sufficiently long to cross. The ladder was accordingly laid down, and was seen to rest upon the opposite edge, but its bearing did not exceed an inch on either side. We now considered that, should we pass the chasm, and should its opening, which had enlarged so much in the course of a few preceding days, increase in the least degree before the time of our descent, no chance of return remained. We also considered that, if the clouds which so often enve

lope the hill should rise, the hope of finding, amidst the thick fog, our way back to this only place in which the gulf, even in its present state, was passable, was little less than desperate. Yet, after a moment's pause, the guides consented to go with me, and we crossed the chasm. We had not proceeded far when the thirst, which, since our arrival in the upper regions of the air, had been always troublesome, became almost intolerable. No sooner had I drank than the thirst returned, and in a few minutes my throat became perfectly dry. Again I had recourse to the water, and again my throat was parched. The air itself was thirsty; its extreme of dryness had robbed my body of its moisture. Though continually drinking, the quantity of my urine was almost nothing; and of the little there was, the colour was extremely deep. The guides were equally affected. Wine they would not taste; but the moment my back was turned, their mouths were eagerly applied to my cask of water. Yet we con

tinued to proceed till seven o'clock; when, having passed the place where M. de Saussure, who was provided with a tent, had slept the second night, we sat down to breakfast. All this time the thermometer was 4° below the freezing point. We were now at the foot of Mount Blanc itself; for, though it is usual to apply that term to, the whole assemblage of several successive mountains, yet the name properly belongs only to a small mountain of pyramidal form that rises from a narrow plain which at all times is covered with snow. Here the thinness of the atmosphere

atmosphere began to affect my head with a dull and heavy pain. I also found, to my great surprise, an acute sensation of pain, very different from that of weariness, immediately above my knees. Having finished our repast, we pursued our journey, and soon arrived at a chasm which could not have existed many days, for it was not formed at the time of M. de Saussure's ascent. Misled by this last circumstance, for we concluded that, as he had seen no rents whatever from the time that he passed the place where he slept the second night, none were likely to be formed, we had left our ladder about a league behind; but as the chasm was far from wide, we passed it on the poles that we used for walking; an expedient which suggested to me that the length of our ladder might be easily increased by the addition of several poles laid parallel and fastened to its end; and that the hazard of finding our retreat cut off from the enlargement of the chasms might by this means be materially diminished. At this place I had an opportunity of measuring the height of the snow which had fallen during the preceding winter, and which was distinguished by its superior whiteness from that of the former year. I found it to be five feet. The snow of each particular year appeared as a separate stratum; that which was more than a twelvemonth old was perfect ice; while that of the last winter was fast approaching to a similar state. At length, after a difficult ascent, which lay among precipices, and during which we were often obliged to employ the hatchet in making a footing for

our feet, we reached and reposed ourselves upon a narrow flat which is the last of three from the foot of the small mountain, and which, according to M. de Saussure, is but 150 fathoms below the level of the summit. Upon this platform I found a beautiful dead butterfly, the only appearance which, from the time I entered on the snow, I had seen of any animal. The pernicious effects of the thinness of the air were now evident on us all; a desire, almost irresistible, of sleep came on. My spirits had left me; sometimes indifferent as to the event, I wished to lie down; at others, I blamed myself for the expedition; and, though just at the summit, had thoughts of turning back, without accomplishing my purpose. Of my guides many were in a worse situation; for, exhausted by excessive vomiting, they seemel to have lost all strength, both of mind and body. But shame at length came to our relief. I drank the last pint of water that was left, and found myself amazingly refreshed. Yet the pain in my knees had increased so much, that at the end of every 20 or 30 paces I was obliged to rest till its sharpness was abated. My lungs with difficulty performed their office, and my heart was affected with violent palpitation. At last, however, but with a sort of apathy which scarcely admitted the sense of joy, we reached the summit of the mountain; when six of my guides, and with them my servant, threw themselves on their faces, and were immediately asleep. I envied them their repose; but my anxiety to obtain a good observation for the latitude subdued my

wishes for indulgence. The time of my arrival was half an hour after ten; so that the hours which had elapsed from our departure from Chamouni were only 27, 10 of which we had passed in the hut. The summit of the hill is formed of snow, which spreads into a sort of plain which is much wider from E. to W. than from N. to S., and in its greatest width is perhaps 30 yards. The snow is every where hard, and in many places is covered with a sheet of ice. When the spectator begins to look round him from this elevated height, a confused impression of immensity is the first effect produced upon his mind; but the blue colour, deep almost to blackness, of the canopy above him soon arrests his attention. He next surveys the mountains; many of which, from the clearness of the air, are to his eye within a stone's throw from him; and even those of Lombardy (one of which appears of an altitude but little inferior to that of Mount Blanc) seem to approach his neighbourhood; while on the other side the vale of Chamouni glittering with the sunbeams is to the view directly below his feet, and affects his head with giddiness. On the other hand, all objects of which the distance is great, and the level low, are hid from his eye by the blue vapour which intervenes, and through which I could not discern the Lake of Geneva, though at the height of 15,700 English feet, which, according to M. de Saussure, was the level on which I stood: even the Mediterranean Sea must have been within the line of vision. The air was still; and the day so re

markably fine, that I could not discover in any part of the heavens the appearance of a single cloud. As the time of the sun passing the meridian now approached, I prepared to take my observation. I had with me an admirable Hadley's sextant, and an artificial horizon, and I corrected the mean refraction of the sun's rays. Thus I was enabled to ascertain with accuracy that the latitude of the summit of Mount Blanc is 45° 49′ 59′′ North.

I now proceeded to such other observations as the few instruments which I had brought permitted me to make. At twelve o'clock the mercury in the thermometer stood at 38° in the shade; at Chamouni, at the same hour, it stood when in the shade at 78°. I tried the effect of a burning glass on paper, and on a piece of wood, which I had brought with me for the purpose, and found (contrary, I believe, to the gene. rally received opinion) that its power was much greater than in the lower regions of the air. Having continued two hours on the summit of the mountain, I began my descent at half an hour after twelve. I found that, short as my absence had been, many new rents were opened, and that several of those which I had passed in my ascent were become considerably wider. In less than six hours we arrived at the hut in which we had slept the evening before, and should have proceeded much further down the mountain had we not been afraid of passing the Glaciere de la Coté at the close of the day, when the snow, from the effect of the sun-beams, was extremely rotten. Our evening's

repast

repast being finished, I was soon asleep; but in a few hours I was awakened with a tormenting pain in my face and eyes. My face was one continued blister, and my eyes I was unable to open; nor was 1 without apprehensions of losing my sight for ever, till my guides told me that if I had condescended to have taken their advice of wearing, as they did, a mask of black crape, the accident would not have befallen me, but that a few days would perfectly restore the use of my eyes. After I had bathed them with warm water for half an hour, I found to my great satisfaction that I could open them a little, on which I determined upon an instant departure, that I might cross the Glaciere de la Coté before the sun was sufficiently high for its beams to be strongly reflected from the snow. But unluckily the sun was already above the horizon; so that the pain of forcing open my eyes in the bright sunshine, in order to avoid the chasms, and other hazards of my way, rendered my return more irksome than my ascent. Fortunately one of the guides, soon after I had passed the glaciere, picked up in the snow a pair of green spectacles, which M. Bourrit had lost, and which gave me wonderful relief.

At eleven o'clock on Aug. 10, after an absence of 52 hours, of which 20 were passed in the hut, I returned again to the village of Chamouni. From the want of instruments (the scale of the barometers I had, being graduated no lower than 20 inches, which was not sufficiently extended) the observations I made were but few. Yet the effects which the air in

the heights I visited produced on the human body may not perhaps be considered as altogether uninteresting, nor will the proof I made of the power of the lens on the summit of Mount Blanc, if confirmed by future experiments, be regarded as of no account in the theories of light and heat. At any rate, the having determined the latitude of Mount Blanc may assist in some particulars the observations of such persons as shall visit it in future; and the knowledge which my journey has afforded, in addition to that which is furnished by M. de Saussure, may facilitate the ascent of those who, with proper instruments, may wish to make in that elevated level experiments in natural philosophy.

Notes of a Mineralogical Excursion to the Giant's Causeway. By the Rev. Dr. Grierson.

(From the same.)

I left Coleraine on the morning of Sept. 17, in company with a gentleman of that place, whose obligingness, intelligence, hospitality, and kindness, afforded me a most agreeable specimen of the Irish character; and proceeded to the Giant's Causeway. The day was charming; and it is not easy for me to express the gratification I felt, as we made our way through a fine and gently varied district, at the idea of having it in my power soon to contemplate in favourable circumstances one of the most stupendous and interesting natural phenomena that are any where to be seen. From Coleraine to the Causeway is eight

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