power, and then you can judge for your-fords ample supplies of fuel to the traveler selves." So up went the cloth, down bent when he wants to cook his provisions, or the tent-pole; the canvas flapped and to protect himself from the cutting cold quivered in the blast; and a blinding of the night. And when night does come, volley of gravel was showered over the how greatly is the loveliness of the scene person of the intrusive Professor. enhanced. "There was," says Professor Smyth, the silence and stillness of death." It was a silence which would have been striking even to Ossian's heroes of the mist and ghosts of the hills. For, on Teneriffe, there were no gurgling torrents, no madly-rushing cataracts to keep the mountain awake with their sleepless roar. Not a single stream existed to enliven this Sahara of sound. To the listener, in the dead of night, far above the levels of human life, the utter taciturnity of Nature is more solemn, and perhaps more stunning, than the crashes of her loudest thunder. "A faint tinkle, tinkle, now and then from a stray goat was the only sound to be heard during this anxious period; and though the crea ture was far off, one could distinguish whenever it stopped to browse on some solitary retama bush, and then when it trotted off to find another." In spite of these boisterous aborigines, however, the invaders held their ground, and made themselves as much at home as circumstances would permit. In truth, it was a lonely world. There they were, nearly 9000 feet above the haunts of men, dwelling in a volcanic wilderness, and on the very margin of a great crater, whose diameter was not less than eight miles. Within ten paces of the station a tremendous precipice commenced, with a plunge of more than 1500 feet. Hovering over the sea, half way beneath their position, the clouds brought by the trade-wind formed themselves into a plateau of gray vapor, which extended to the horizon on every hand; and so even was its surface, that the spectator fancied he might have walked across on its pavement of watery vesicles to the island of Palma, which showed its summits in the distance. This hanging-plain, however, did not approach close to the mountain side. A rim of cloud, lower in elevation, and thinner in substance, ran round the cliffs, as if attached to their flanks, like the "ice foot" of the polar shores. Generally there was an interval between the two strata of vapor, through which the ocean might be seen-sometimes whipped into foam under the breeze, whilst the winds might perhaps be hushed, and all was calm on the brow of the rock. At this height, and in such a stony region, the powers of vegetation seemed to be well nigh exhausted. Yet as if to show how happily Nature can still employ her energies in the most unfavorable circumstances, one bush springs up when all others have succumbed to the rigors of the locality. This is the retama, (cytisus nubigenus.) It is required to grow in a cindery soil, and on declivities where the particles are kept in constant Does dryness increase or decrease as we motion, gliding along like a powdered ascend? When we look upwards, and glacier, but with a much swifter pace. It see whole acres of vapor floating at great must vegetate, too, in an arid atmosphere, heights in the air-when we observe the far above the ordinary line of mist, and gray mists gathering in solemn convocaon ground rarely refreshed by summer tion upon the summits of the hills, and showers. Yet this brave little plant shrouding them for days together, we strikes its roots into the earth, and man- might naturally assume that the elevated ages to gain a firm footing on the treach- regions of the earth must be more watery erous slopes. There it flourishes on the than the inferior. We should say that meagerest allowance of moisture, and af-the man who proposes to live in nubibus What, then, were the scientific questions to which the attention of the Professor was turned whilst dwelling in these towering solitudes? We can only give a few illustrations. If the reader should be a bit of a meteorologist, or will be kind enough to consider himself such for a few moments, he will doubtless take some interest in the humidity of the upper air. We don't ask him to display any passionare attachment to hygrometers, nor do we expect that he will feel particularly enthusiastic on the subject of mountain moisture in general. But when he learns that this topic has been the bone of philosophical contention that rival theories exist on the point, and that each of these has been demonstrated to the satisfaction of its upholders, he will probably prick up his ears, and even long to have a finger in the fight. for a time ought to take a quantity of unbrellas and mackintosh garments, unless, like a pillar saint of old, he considered it part of his penance to endure all the vicissitudes of the weather without protection. Explorers, too, in various quarters have observed much to confirm this plausible conclusion. Thus, at Table Mountain, the traveler begins with arid sand, which exhibits the characteristic vegetation of a dry region, and ends with boggy flats, where reeds and marshy plants abound, and the air is charged with a cold wet mist. But when Saussure and Deluc came down from the Alps, hygrometer in hand, their instrumental readings appeared to be quite inconsistent with this view. Humboldt's American researches confirmed the doubts of the French philosophers. Various æronauts have also added their observations, and these, says Professor Smyth, "have now unalterably established the fact that, from the surface of the earth up to the level of the first Newton's grosser clouds, moisture evidently increases; but above that level suddenly and greatly decreases, barring exceptional cases, to more than African dryness." At any rate, the question might be fairly tried on the pinnacles of Teneriffe. Unfortunately, the Professor has given us no hygrometric observations taken at the level of the sea, nor any particulars of atmospheric pressure in the lowlands, from which the full value of his results might be determined. In truth, this want of comparative data generally greatly impairs the scientific sufficiency of his book, and lays his conclusions open to the assumption that they may have sometimes been founded on partial or transitory conditions. If provision was not made for the simultaneous registration of all meteorological changes beneath as well as above the clouds of the Peak, so far as this could be done, we think it was a flaw in the arrangements of an excellent and laudable expedition. But however this may be, many of the facts adduced by the Professor show that, instead of a sloppy atmosphere, as the first theory would lead us to expect on Teneriffe, the dryness of its upper stories, at this season of the year, was quite remarkable. On ascending the mountain, the lips of the party began to split, the skin cracked, the nails became exceedingly brittle, the hair grew crisper and more frizzly, and the faces of the travelers were soon browned and blistered by the sun. The bread became so desperately hard in the course of half a day, that even nautical teeth would have gnawed through it with some difficulty, and a set of iron incisors alone could have done adequate justice to such fare. Sad havoc was made with the scientific tackle in consequence of the extreme aridity of the air. Cracks opened in the photographic apparatus, and pictures came out with ugly black lines across their surface. Fissures, into which you might insert a finger, were discovered in the lids of gay mahogany cases. The wooden scale of a thermometer bent into such a curve that the tube was snapped, and the central portion driven to a considerable distance. The microscopical glasses were found glued into a nauseous lump by the shrinking of the cork in a bottle of viscid Canada balsam. The electrometer was damaged by the contraction of its base on the glass bell, and the magnetometer suffered acutely from the warping of the wood, until relieved by chisels and penknives. Queerest of all disasters, perhaps, was that which happened to a box. On attempting to lift it carefully by both handles, the lid and sides alone responded to the call; the body, with its lockers and contents, remaining behind, as if the tenacity of the glue had been totally destroyed. There was certainly one advantage arising from this dessication of the air. The bushes gathered by the travelers burn readily even in their green and youthful condition. The retama made brilliant fires, particularly when assisted by the codeso, otherwise adenocarpus frankenoides-what imposing titles botanists do give poor little bushes! The Professor is warm in his praises of their culinary services. The one began the blaze right joyously-the other continued the good work with its more substantial stuff. Hence the pot boiled merrily in the mountain air. But, of course, as the pressure of the atmosphere was so much less, the point of ebullition must needs be so much lower. At the very top of the central cone the boiling temperature was afterwards found to be about 191°; consequently, if articles had to be seethed or decocted at this elevation, upwards of twenty degrees of good caloric would have been cut off from the service of the cook, and the operation must have been continued for a lengthened period if the full benefit of vineyards beneath; but Providence has kindly enjoined them to reserve their contents for more northerly climes. Why? Each atom of vapor they transport has been raised in a region of sunshine, and bears with it a quantity of tropical warmth. On mixing with the cold air of less favor gives out its latent heat. Thus the temperature of lands like Great Britain is ameliorated-in fact, supported-by reg ular subsidies of warmth from the South, That great current conscientiously abstains from expending any considerable quantity of moisture until it reaches the region of comparative cold, as if it knew it was freighted with the most precious of principles, that its drops were the glad carriers of caloric, and that many a fair land might wither were this fleet of golden vesiclesargosies more richly laden than those of Mexico or Peru-staid in its course or diverted to another destination. the process was to be obtained. Some- [S. W. winds do occasionally let fall a few times this circumstance has been produc- drops upon the mountain, and upon the tive of much annoyance to travelers. Can you get eggs delicately done-can you procure first-rate tea, if the water goes off in steam, when it reaches a temperature of little more than 191°? The Professor not only thinks it possible, but seems to laugh at the difficulties which other explorers appear to have encountered latitudes, this vapor condenses and ed. Mrs. Smyth, who is capital at a cup of tea, triumphed over the atmosphere, and even produced a more excellent beverage in excelsis than she could have done in the valleys. This the Professor explains on the principle, that as the air is expelled from the leaves at a lower temperature, their flavor is not dissipated to the same extent by the application of heat. But if this be correct, what of the eggs and similar commodities? Mr. Darwin tells us that whilst high up amongst Andes, his party found their potatoes as hard as ever after several hours' boiling. The pot was kept on the fire all night; the operation was continued next morning; but still the vegetable remained perfectly obdurate. Two of his attendants were heard discussing the phenomenon, and the conclusion they formed was that the vessel must be bewitched. "It takes nearly as long again," says a visitor to the Hospice of St. Bernard, "to cook meat as it would if the water boiled at the ordinary point of 212°. The fire must be kept glowing, and the pot boiling five hours, to cook a piece of meat which it would have taken only three hours to get ready for the table if the water would only have waited till 212°. This costs fuel, so that a dish of bouilli makes the monks consume an inordinate quantity of wood in the kitchen." Rain, of course, could scarcely be expected at this season of the year. Were not the clouds brought by the trade winds some thousands of feet beneath their position? It is true the great counter current which flows from the equator to the poles was streaming steadily along in the upper regions of the atmosphere, but it was too high in its course to deposit its moisture upon a region so little removed frem the tropical belt. Let it travel to the latitude of the British islands, and there, having descended to a lower level and entered a colder sky, it would drench the natives, as it was frequently doing at that very period. These high Another interesting question was to determine the amount of solar radiation in these elevated tracts. In other words, what was the strength of the sun's rays before they plunged into the denser part of the atmosphere, and sacrificed a large portion of their caloric in their transit through the ocean of vapor below? Here the good reader must distinguish between temperature and radiation. They are different things. The one may be represented by the climate of the room in which you sit: the other by the direct influences of the fire which enlivens the apartment. The thermometer may indicate a general warmth of sixty or seventy degrees; but let it gradually approach the hearth, and the quicksilver will mount until it has reached the top of its calorific gamut and fractured the tube in its expansive rage. Now judging from the nightcaps of snow which are worn by the tallest mountains, and remembering that if we could climb to the height of some 15,000 feet at the Equator itself we should find every pinnacle coated with ice, we might conclude that the sun's beams must be less powerful in these lofty solitudes than in the humbler plains. It would be a great mistake. It certainly sounds like a paradox to say that if the Tower of Babel had been completed, the garrets would have been white with frost, and the inhabitants of the upper stories shivering with cold, though the direct heat of the sun would be considerably greater than that received from him at the groundfloors of the pile. Such, however, would unquestionably have been the case. The depth and density of the atmosphere explain the phenomenon. Let a schoolboy possessed of a convex lens, and eager as all schoolboys are, when so enriched, to burn holes in the hands of their companions, try the pleasing experiment when the sun is declining in the heavens, and he will find it difficult to make a proper impression upon the cuticle of his patient; but let him operate towards the middle of the day, and the writhings of his victim will soon assure him that he has completely succeeded in his little auto-da-fé. The solar rays have in fact to traverse a much greater extent of air when the sun is on the horizon than when he is in the zenith, and consequently are shorn of much of their calorific power before they alight on the earth. This loss has been variously estimated. Few have reckoned it at much less than a third of the heat of the beam when it first strikes upon our atmosphere and some have supposed that at least seventy parts out of every hundred are intercepted in the vertical descent of a ray. Not that all this valuable warmth is idly squandered; on the contrary, it is absorbed by the air and vapors, and thus serves to heat the great transparent garment which nature has so magnificently woven for the protection of the globe. But if the upper parts of the atmosphere arrest the choicest portions of the solar fire, why should they not be warmer than the lower? Such, indeed, would be the case, were the air of equal density throughout. But it is not. Its rarity increases in proportion as we ascend, and consequently its capacity for heat augmenting, there is not the same palpable manifestation of warmth in these lofty regions which we expect, and, in fact, experience at the surface of the earth. Neither can the superior strata of the atmosphere profit by the radiation which goes on from the ground, and tends to keep up the temperature of the strata contiguous to the soil. Hence though the attics of the globe receive the "pick" of the sunshine -the virgin effusions of the solar furnace, if we may so speak-the air around is unable to fund the glorious fire so as to raise its own sensible temperature to an equivalent height. These things considered, we shall not be surprised to learn how Professor Smyth's thermometers conducted themselves on the mountains of Teneriffe. On the first day of trial a patent instrument was shattered by the sunshine. It was only qualified to mark a temperature of 140 degrees, but when exposed to the direct rays of the luminary, the quicksilver rose so rapidly that it soon reached this limit, and broke the tube in its efforts to expand. With instruments of higher capabilities the observations were continued, and by noon the mercury stood at 168°. Still more striking results were attained on a subsequent day. One calm morning the fluid ascended to 180° by half-past nine o'clock, and at twelve o'clock it had flowed over, and half filled a kind of safety cistern, the apparatus being only graduated to that extent. But on the 4th of August the sun seemed to come out in such force that you might have thought Phæton was in charge of his chariot once more. The Professor calculated his heat at 212 degrees! This, as the reader will remember, is the boiling point of water at the level of the sea, and much higher than the boiling point at the summit of a tall mountain. Could the direct temperature of the sun have been imparted to the air and the rock, the climate of Guajara would have surpassed that of the Piombi at Venice, or the Black Hole at Calcutta. The bare foot could not have rested on the ground; the hands could not have touched any object without being blistered; the lungs would have drunk in the attenuated air with fearful gaspings; and the fluids of the body must have exhaled so rapidly, that the traveler would soon become little better than an animated mummy. Yet here, where the fiery shafts from the great luminary might be expected, as a Cape boer remarked of the African orb, to "stick you through" on the spot, they fall harmlessly upon the earth; and here, where we might fancy the ground would be scorched and blackened by exposure to the artillery of the sun, playing upon it without a cloud to break its force, the practical temperature ranged from 60° to 67°! Under cover, the mercury stood at the first of these figures on the day when the exposed bulbs intimated that they were at the boiling point. The direct power of the sunshine therefore, over and above the temperature of the hour, was equivalent to 150 degrees! It is clear, therefore, that the tops of great mountains are not places where we could advise ladies to indulge in a summer sojourn. What would become of their complexions under the fierce outpourings of a tropical sun? Could baths of Kalydor keep their skins in the fair and dainty condition which it is the glory of the sex to maintain? Would it not be requisite to establish dépôts of parasols above the clouds, and to enlarge the dimensions of the round-hats, so as to bring them up by a small addition, it is trueto the circumference of a coach-wheel? Even in the nether lands of the Canaries, men-and these young active Britons, too -might be seen walking about with blue spectacles on their eyes, and green umbrellas unfurled over their heads. And if bearded people could do this at the level of the sea, could we expect ladies, who have a natural antipathy to tanned visages and crops of freckles, to intrust themselves to the sun in his own hill territory, unless provided with the amplest silken shields, or protected by the immensest straw-canopies? How Mrs. Smyth braved the exposure we are not informed, and it would be impertinent in us to conjecture, even as a matter of pure scientific curiosity. literally extinguished on the photographic plate. Aloft at Alta Vista there had been no difficulty in obtaining pictures of the crater-wall at a distance of four miles, in which every ridge, and almost every bush, stamped itself permanently on the silver mirror of the camera; but here, as the author forcibly remarks, the photographic apparatus could only produce" a dim outline of a mountain looming through a chemical fog, where the eye, though sensible of an atmosphere, saw all the lights and shadows of the cliff." Professor Smyth also made a dash at another vexata quæstio in science. Do the rays of the moon yield any appreciable heat? That we can not warm our hands in her rays that cats are rarely found basking in her presence as they do in the glories of the sun-are matters of universal observation; but if she affords so much light, why should she not also afford some caloric ? We do not ask for much. A trifle will suffice. But surely it does not seem unreasonable to suppose that if she reflects so considerable an amount of solar illumination, she should also be able to transmit us some noticeable dividend of solar warmth. Time after time philosophers have experimented on her beams. They have tried her with the most sensitive thermometers; but she would not raise the fluid through the smallest fraction of a degree. They have concentrated her rays by means of reflectors, and brought them to a focus on the bulb of the instrument; yet, though metals would have flashed into vapor under such a test had the sun been the operator, the poor moon did not appear to have fire enough to stir the mercury at all. At length Melloni questioned her with his thermo-multiplier But if the sun's calorific rays were so far intensified in excelsis, what effect would the abstraction of 9000 or 10,000 feet of atmosphere produce upon his chemical beams? After the Professor's descent from the clouds, he took up his photographic implements to the roof of the hotel. He wanted the peak to sit for its portrait. The day was beautifully clear, and every great feature in the mountain was distinctly visible to the eye. There was the steep ridge of Tigayga, for example, with its variegated flanks, glitter--an apparatus of rare susceptibility-and ing in direct frontage to the morning sun. The first plate, however, which issued from the camera contained no Tigayga at all! "Not a ghost of it or of its brethren appeared on the collodion film. We tried another and another, ringing all the changes of long and short exposure, positive and negative developers yet all to no avail, the detail of the escarpment would not come out. There was only the sky line and a flat tint within that; as if the sun were behind, and not in front of the mountain." Where was Tigayga gone? The atmosphere had intercepted so many of the chemical rays, that it was to him she seemed to reply that she was not the perfect icicle men supposed. So faint, however, was her response, that it has generally been ignored, and the feeble results obtained were ascribed to some disturbing causes; for the process is one of such delicacy that the observer may easily credit the moon with the very caloric which emanates from his own person. In fact, many people seem disposed to adhere to the old fancy, that the lunar rays produce a positive chill. There are gardeners who feel deeply aggrieved by the proceedings of the "Red moon "--one which is on duty in the heavens in April |