The Press. — London, England, 1858-02-13 00:00:00

162 The Professor of Practical Astronomy in the University of Edinburgh was the fittest person to undertake such an experiment as the ascent of the Peak of Teueriffe, and to render us an account of his astronomical observations above the clouds. His previous expeditions at the Cape had given him that practical experi ence so essential to the success of such an undertaking, while his high scientific attain ments peculiarly fitted him for the conduct of the proposed expedition. It was in May, 1858, that the Admiralty, upon the recom mendation of the Astronomer Royal, intrusted Professor Smyth with 500/., and no instruc tions, and towards the end of June in that year the learned Professor, accompanied by his wife, set sail fin. Teneriffe in Mr. Stephen son's yacht Titania, whicb, with a liberality that did honour to him, had been placed at the entire disposal of the astronomer. The expe dition arrived in safety at Santa Cruz, and it having been resolved to send the yacht round to Orotava—a port on the other side of the island, and from which the ascent of the Peak is most easily achieved—on the 1 lth July the instruments and camp equipage were safely landed, and three days afterwards, with more than twenty horses and mules, and as many muleteers, the ascent was commenced. Our estimate of the Professor as a practical man is best sceu in his little losS of time to attain the object of his journey. With true scientific thirst he rested not until he had "eliminated " the lower third part of the atmosphere." The ascent was first directed to the top of the Guajara, a mountain nearly 9,000 feet high, and four miles south of the " Pico," the sum mit of which was unattainable by mules, and the abundant escape of hot vapours from which, it was believed, would seriously interfere with the accuracy of telescopic vision. So the Gutijara for first operations was agreed upon, and on the third day the whole party started. With the exception of loose lava and dead wood, the ascent was easy—a gentle slope ;in fact the whole island is one slope, at from 5 deg. to 12 deg. from the level of the sea to the top of the world-famous Peak. The top of the Guajara was reached in one day with out any remarkable incident, except that the mules, unaccustomed to the weight of delicate scientific instruments, became unusually spiteful, and either kicked into one another's 1 tad or relieved themselves by an occasional roll •;er the loose lava. The top reached, the obser vatory was at once established, and the Equa torial telescope mounted in position. At that height the temperature was still high, 74 deg. Fah., but in the dryness of the air there was a remarkable change. The depression of the dew point from 10 deg. in Orotava had increased to 50 deg. "No wonder," writes the learned Professor, " we felt our lips cracking, our hair " frizzling, our nails becoming brittle, and " saw each other's faces scarlet ; for the sun " too was now shining down vehemently " from a high altitude, where the dust " haze no longer dimmed his rays." Cracked lips and frizzled hair were not the least ill the scientific flesh was heir to iu these attitudes of drought—" over aridity de " stroyed the cohesive power of animal " matter," which means that the glue of all the Professor's packing-cases gave way, the handles came off, and the sides carne out, and great occasionally was the fall thereof. Then the cork of a bottle of Canada balsam would shrink " to such an extent, as to let out the " sticky fluid amongst microscopical glasses, " and glue them all into one odious lump ": Worse still, the wooden base of our electrometer, in shrinking on the glass bell, had broken it; and finally the well•seasoned mahogany box of the magnetometer had contracted on its plate glass cover, and forcibly held it in. Fortunately the glass, being half an inch thick, resisted the pressere, until we could come to its assistance with chisels and pen-knives, and cut it out safely from so mur abrous a grip. " These little incidents," observes the Pro fessor, with an eye to business, " has their " scientific uses; for our wet bulb therm°. " meter only gave the measure of dryness at " the instant of observation ; while the effects " on our baggage acted, though vulgarly, the " part of a cumulative instrument, and indi " cated the sum total of drought fur the entire " period of our mountain residence." Some curious atmospheric effects were wit. n-Ased at this elevation. Ahuge stratum of cloud. THE PRESS, FEBRUARY 13, 1858. covered the sea at an altitude of about 5,000 feet, while another at 3,000 feet covered the island; between them the sea was visible curling in foam-waves from a N.E. wind, while on the mountain top they had only a gentle air. The view was "grand and soul-inspiring." The colours of even distant mountains ap peared "as vivid and pure " as on the ground close by, while the shadows are so dark and yet so transparent, "so black-looking amid " the sun lit landscape, and yet in reaity so " richly and deeply coloured, that a full idea " can only be formed, by combining what the " telescope reveals of the powerful lights and " shadows in the moon, with the paintings of " Turner and of Rembrandt." " Each mo " men t," writes the Professor in a burst of natural enthusiasm, "on a day of this sort is " worth hours on any other ; we look at every " thing far and near, see it as it were face to " face, and gain a higher idea of the glorious " creation in which we live ": As the sun descends, the shadow of Guajara is thrown first on the sea, then on the cloud-plain ; and then as the sun actually sets, the shadow crosses the island of Gland Canary, rises into the sky above it, and appears distinct and pronounced as a real mountain; and when presently, almost behind the sharply defined summit of the shadow, the full moon rises, and appears to be the very cause of it, the illusion is extraordinary indeed. . . . . . Turn round quickly though, lest you lose the glories of the west ; ses. how vivid atmospheric colours can be, when there are no impurities in the air. The chief part of the light is yellow, glorious cadmium, passing below into the richest tint of red-orange, shove into lemon-yellow, and then powerful rose-pink, which by degrees fadea into the deep-blue sky above. Underneath all this display is seen the trade-wind cloud-plain, concealing all the distant sea, and forming the horizon on this as on every other side. Of a delicate blue grey, these clouds farm so level a plain, that if only a footing could be obtained on the edge that approaches so close to Teneriffe, one could fancy it to offer an easy walk over to Palma, that rises on the verge of the glowing horizon. While still admiring this scene, night arrives ; one hour five minutes is the observed astronomical time of the dura tion of twilight, but that takes account of far fainter light than what practical persons would deem of any importance; aud half that interval ought to see all wanderings about the mountain terminated. Oo this particular night • larger scope is allowed by tho glories of a full moon, which, soon abandoning the saffron colour with which it rose, mounts up in the sky as a disc of the purest white, and actually seems to stand out in front of the stars, and their back- ground of indigo blue. There was, however, at this height a " dust haze," which seriously interfered with astro nomical vision, and the Professor resolved to try an actual ascent of the Peak, and, if possi ble, the establishment there of a small obser vatoa•y. How he laboured to achieve this end, and how gallantly he encountered and over came all obstacles, our readers will find de tailed in this volume. Suffice it to say that he scaled the central cone with undaunted ardour, and established himself, and soon afterwards Pattinson's Equatorial telescope, in a bed of obsidian on the Great Crater, at a height of some 11,000 feet above the sea level, and within a few hundred feet of the sharp-pointed peak of this majestic mountain, which, rising straight from the ocean to its prodigious eleva tion, stands in I-me grandeur towering above the clouds into the heavens beyond. We have scarcely left.ourselves room to speak of the scientific results of the expedition. In a paper read before the Royal Society on 3rd June, 1557, and reprinted in the Philosophical Transactions, they will be found. The present volume details more the personal experiences under which those observations were made, yet some very interesting scientific results aro stated. Upon the top of the Guajara the maximum heat of solar radiation was esti mated—for from the insufficiency of the instru ment it co rld not be calculated—at 212 deg. 4 min , the temperature in the shade being only 60 deg., thus leaving l 3 deg. for the effect of sunshine at an elevation of t+,900 feet. From this Professor Smyth argues that the higher we ascend, though the lower the tem perature, the greater the solar radiation : Amongst those who have not thought much on radiation, there has arisen au idea, that the closer we go to the sun the less heat do we receive from that great luminary. Consequently, they allege, a comet—which like that of 154:3 passed at its perihelion within 80,000 miles of the surface of the sun—must have suffered rather from cold, the cold of space, than from the excessive heat which astronomers have described ; and the circumstance of per petual snow on the top of our loftiest mountains is pointed to as an illustration of the case. Such snow however, and its perpetuity, are rather to be taken as proofs of tempera ► ture, and of the non-conductive powers of frozen water, than of radiation; and this latter quality we invariably found on Guajara to be the opposite of temperature ; i.e. the days in the which temperature iu the shade was loweat, and we may add when the air was most clear and trails. parent, were precisely the days of highest radiation. With the increase, on the ()tiler hand, of our too frequent visitors, the banks of dust•haze, the height of a thermometer in the shade increased ; while another exposed to the sun's rays invariably decreased. Were it possible to ascend fifty miles above the earth's surface, and so escape altogether from its atmosphere, the temperature of shade might fall to 50 deg., but that of solar exposure, or radiation, would be increased probably some hundreds of degrees, though we had not sensibly altered our distance from the sun. An attempt to obtain instrumental evidence of the moon's radiation was not so satisfactory. On one peculiarly fine, still night, radiation was evident to the extent only of about a third of a degree—according to experiment, just one-third " that of an ordinary candle " at a distance of fifteen feet. The results of the experiments for zodiacal light are too long to enter upon here; but we may observe that they completely overthrow the theory of the American Japan surveyors, who started the theory that the light encircles not the sun bat the earth. Mr. Smyth, as the result of his careful observation, declares the human eyo in his position would have been " unable to " appreciate anything so inconceivably faint " as must he a lunar analogue of the solar zo " diacal light, supposing the latter for a moment " to depend on the sun illuminating a nebulous " ring, encircling not himself but the earth." The famous " lateral oscillation of stars," ob served by Humboldt on th• Alta Vista in 1799, was never seen by Professor Smyth in the whole course of his two mouths' observa tions He regards the phenomenon related by Humboldt as entirely exceptional, "even on " the mountain where it was observed." The geologist, also, will find observations of great interest upon the graver physical fea tures of the Peak—upon the ages of lava streams, upon lava caverns, and upon other volcanic phenomena rare in occurrence and problematical in character. The central cone of the Peak of Teneriffe, Professor Swyth maintains, exhibits secular and periodical qualities coexistent : Examination of the slums which have been sent forth within the memory of man would tell little of secular pro gression; for they only break out about once a century, the last eruption having occurred in 1798 and the previous one in 1703 ; and it is necessary, therefore, to question, as we have done, pre-historic phenomena. This method at once enables us to take up a far more powerful position ; for what a mighty period must have elapsed to include alone the thousands of black streams which now seam thu cone on every side; and finding many of these, that are quite beyond the memory of man, untouched by any oxidating influence—we are inclined to wonder what myriads of ages must have further elapsed to produce the deep red and yellow decompositions, so conspicuous on the surface of still earlier streams. For their blocks are, in the interior, black ; and in chemical composition very similar to the substances last ejected. We have here at all events, whatever the absolute dates, results from an immense duration of periodical effects spread before our eyes; and cannot resist the conclusion which their forms set forth, viz., that a most marked secular change has been wrought out, and that its signs are visible still. Hence, we may state RS the general law, holding good on the whole, not of course in every indi vidual instance any more than that the tide-wave advances uniformly, and without little undulations on its surface, that the earlier streams were the most copious and most fluid ; nay, we may pretty safely add, the hottest also, and that there has been a continual decrease in size and beat ever since. The Peak of Teneriffe has, in fact, been s eadily burning out for ages; and is, happily for inaukind, no longer in its youthful energy, nor in its primeval vigour of destructive power. The ascent to the top of the Peak ought not to be spoken of as difficult " by any man tra. yeller," says the learned Professor ; but eager aspirants to crown the Peak must remember this is the opinion of a saran in pursuit of a crater, and to such a man, under such circum stances, loose pumice and lava crags, to say nothing of holes and cracks and sulphurcous vapours, are pleasant stimulants to the pur suit of science. But let us hasten with the Professor to the top of the crater:— Fagli !—on inhaling the first whiff one was inclined to beat an instant retreat for a few steps ; looking for the moment with infinite disgust ou the whole mountain, as nothing more than the chimney, 12,200 feet high, of one of Nature's chemical inanufsctories. This chimney haying been built at great expense, she was resolved to turn it to account. We, curiously foolish creatures, bad been innocently creeping up the sides; and were now astonished to find, on peering over the mouth of the long stalk, that noisome fumes were ascending from it The north-eastern, northern, and north-western were the highest, whitest, and betted', parts of the crater walls