Shall I tell you anything of my own poor and superannuated works? The sixth volume is wanting to my "Geography of the Fifteenth Century" (Examen Critique). It will appear this summer. I am also printing the second volume of a new work to be entitled "Central Asia." It is not a second edition of "Asiatic Fragments," but a new and wholly different work. The thirty-five sheets of the last volume are printed, but the two volumes will only be issued together. You can judge of the difficulty of printing at Paris and correcting proofs here,—at Poretz or at Toplitz. I am just now beginning to print the first number of my physics of the world, under the title of "Cosmos:" in German, "Ideen zur erner physischen Weltbeschreibung." It is in no sense a reproduction of the lectures I gave here. The subject is the same, but the presentation does not at all recall the form of a popular course. As a book, it has a somewhat graver and more elevated style. A "spoken book" is always a poor book, just as lectures read are poor however well prepared. Published courses of lectures are my detestation. Cotta is also printing a volume of mine in German, "Physikalische geographische Erinnerungen." Many unpublished things concerning the volcanoes of the Andes, about currents, etc. And all this at the age when one begins to petrify! It is very rash! May this letter prove to you and to Madame Agassiz that I am petrifying only at the extremities, —the heart is still warm. Retain for me the affection which I hold so dear.
A. DE HUMBOLDT.
In the following winter, or, rather, in the early days of March, 1841, Agassiz visited, in company with M. Desor, the glacier of the Aar and that of Rosenlaui. He wished to examine the stakes planted the summer before on the glacier of the Aar, and to compare the winter and summer temperature within as well as without the mass of ice. But his chief object was to ascertain whether water still flowed from beneath the glaciers during the frosts of winter. This fact would have a direct bearing upon the theory which referred the melting and movement of the glaciers chiefly to their lower surface, explaining them by the central heat of the earth as their main cause. Satisfied as he was of the fallacy of this notion, Agassiz still wished to have the evidence of the glacier itself. The journey was, of course, a difficult one at such a season, but the weather was beautiful, and they accomplished it in safety, though not without much suffering. They found no water except the pure and limpid water from springs that never freeze. The glacier lay dead in the grasp of winter. The results of this journey, tables of temperature, etc., are recorded in the "Systeme Glaciaire."
In E. Desor's "Sejours dans les Glaciers" is found an interesting description of the incidents of this excursion and the appearance of the glaciers in winter. In ascending the course of the Aar they frequently crossed the shrunken river on natural snow bridges, and approaching the Handeck over fearfully steep slopes of snow they had some difficulty in finding the thread of water which was all that remained of the beautiful summer cascade. On the glacier of the Aar they found the Hotel des Neuchatelois buried in snow, while the whole surface of the glacier as well as the surrounding peaks, from base to summit, wore the same spotless mantle. The Finsteraarhorn alone stood out in bold relief, black against a white world, its abrupt slopes affording no foothold for the snow. The scene was far more monotonous than in summer. Crevasses, with their blue depths of ice, were closed; the many-voiced streams were still; the moraines and boulders were only here and there visible through the universal shroud. The sky was without a cloud, the air transparent, but the glitter of the uniform white surface was exquisitely painful to the eyes and skin, and the travelers were obliged to wrap their heads in double veils. They found the glacier of Rosenlaui less enveloped in snow than that of the Aar; and though the magnificent ice-cave, so well known to travelers for its azure tints, was inaccessible, they could look into the vault and see that the habitual bed of the torrent was dry. The journey was accomplished in a week without any untoward accident.
In the summer of 1841 Agassiz made a longer Alpine sojourn than ever before. The special objects of the season's work were the internal structure of these vast moving fields of ice, the essential conditions of their origin and continued existence, the action of water within them as influencing their movement, and their own agency in direct contact with the beds and walls of the valleys they occupied. The fact of their former extension and their present oscillations might be considered as established. It remained to explain these facts with reference to the conditions prevailing within the mass itself. In short, the investigation was passing from the domain of geology to that of physics. Agassiz, who was as he often said of himself no physicist, was the more anxious to have the cooperation of the ablest men in that department, and to share with them such facilities for observation and such results as he had thus far accumulated. In addition to his usual collaborators, M. Desor and M. Vogt, he had, therefore, invited as his guest, during part of the season, the distinguished physicist, Professor James D. Forbes, of Edinburgh, who brought with him his friend, Mr. Heath, of Cambridge.* (* As the impressions of Mr. Forbes were only made known in connection with his own later and independent researches it is unnecessary to refer to them here.) M. Escher de la Linth took also an active part in the work of the later summer. To his working corps Agassiz had added the foreman of M. Kahli, an engineer at Bienne, to whom he had confided his plans for the summer, and who furnished him with a skilled workman to direct the boring operations, assist in measurements, etc. The artist of this year was M. Jacques Burkhardt, a personal friend of Agassiz, and his fellow-student at Munich, where he had spent some time at the school of art. As a draughtsman he was subsequently associated with Agassiz in his work at various times, and when they both settled in America Mr. Burkhardt became a permanent member of Agassiz's household, accompanied him on his journeys, and remained with him in relations of uninterrupted and affectionate regard till his own death in 1867. He was a loyal friend and a warm-hearted man, with a thread of humor running through his dry good sense, which made him a very amusing and attractive companion.
As it was necessary, in view of his special programme of work, to penetrate below the surface of the glacier, and reach, if possible, its point of contact with the valley bottom, Agassiz had caused a larger boring apparatus than had been used before, to be transported to the old site on the Aar glacier. The results of these experiments are incorporated in the "Systeme Glaciaire," published in 1846, with twenty-four folio plates and two maps. They were of the highest interest with reference to the internal structure and temperature of the ice and the penetrability of its mass, pervious throughout, as it proved, to air and water. On one occasion the boring-rod, having been driven to a depth of one hundred and ten feet, dropped suddenly two feet lower, showing that it had passed through an open space hidden in the depth of the ice. The release of air-bubbles at the same time gave evidence that this glacial cave, so suddenly broken in upon, was not hermetically sealed to atmospheric influences from without.
Agassiz was not satisfied with the report of his instruments from these unknown regions. He determined to be lowered into one of the so-called wells in the glacier, and thus to visit its interior in person. For this purpose he was obliged to turn aside the stream which flowed into the well into a new bed which he caused to be dug for it. This done, he had a strong tripod erected over the opening, and, seated upon a board firmly attached by ropes, he was then let down into the well, his friend Escher lying flat on the edge of the precipice, to direct the descent and listen for any warning cry. Agassiz especially desired to ascertain how far the laminated or ribboned structure of the ice (the so-called blue bands) penetrated the mass of the glacier. This feature of the glacier had been observed and described by M. Guyot (see page 292), but Mr. Forbes had called especial attention to it, as in his belief connected with the internal conditions of the glacier. It was agreed, as Agassiz bade farewell to his friends on this curious voyage of discovery, that he should be allowed to descend until he called out that they were to lift him. He was lowered successfully and without accident to a depth of eighty feet. There he encountered an unforeseen difficulty in a wall of ice which divided the well into two compartments. He tried first the larger one, but finding it split again into several narrow tunnels, he caused himself to be raised sufficiently to enter the smaller, and again proceeded on his downward course without meeting any obstacle. Wholly engrossed in watching the blue bands, still visible in the glittering walls of ice, he was only aroused to the presence of approaching danger by the sudden plunge of his feet into water. His first shout of distress was misunderstood, and his friends lowered him into the ice-cold gulf instead of raising him. The second cry was effectual, and he was drawn up, though not without great difficulty, from a depth of one hundred and twenty-five feet. The most serious peril of the ascent was caused by the huge stalactites of ice, between the points of which he had to steer his way. Any one of them, if detached by the friction of the rope, might have caused his death. He afterward said: "Had I known all its dangers, perhaps I should not have started on such an adventure. Certainly, unless induced by some powerful scientific motive, I should not advise any one to follow my example." On this perilous journey he traced the laminated structure to a depth of eighty feet, and even beyond, though with less distinctness.
The summer closed with their famous ascent of the Jungfrau. The party consisted of twelve persons Agassiz, Desor, Forbes, Heath, and two travelers who had begged to join them,—M. de Chatelier, of Nantes, and M. de Pury, of Neuchatel, a former pupil of Agassiz. The other six were guides; four beside their old and tried friends, Jacob Leuthold and Johann Wahren. They left the hospice of the Grimsel on the 27th of August, at four o'clock in the morning. Crossing the Col of the Oberaar they descended to the snowy plateau which feeds the Viescher glacier. In this grand amphitheatre, walled in by the peaks of the Viescherhorner, they rested for their midday meal. In crossing these fields of snow, while walking with perfect security upon what seemed a solid mass, they observed certain window-like openings in the snow. Stooping to examine one of them, they looked into an immense open space, filled with soft blue light. They were, in fact, walking on a hollow crust, and the small window was, as they afterward found, opposite a large crevasse on the other side of this ice-cavern, through which the light entered, flooding the whole vault and receiving from its icy walls its exquisite reflected color.* (* The effect is admirably described by M. Desor in his account of this excursion, "Sejours dans les Glaciers" page 367.)
Once across the fields of snow and neve, a fatiguing walk of five hours brought them to the chalets of Meril,* (* Sometimes Moril, but I have retained the spelling of M. Desor.—E.C.A.) where they expected to sleep. The night which should have prepared them for the fatigue of the next day was, however, disturbed by an untoward accident. The ladder left by Jacob Leuthold when last here with Hugi in 1832, nine years before, and upon which he depended, had been taken away by a peasant of Viesch. Two messengers were sent in the course of the night to the village to demand its restoration. The first returned unsuccessful; the second was the bearer of such threats of summary punishment from the whole party that he carried his point, and appeared at last with the recovered treasure on his back. They had, in the mean while, lost two hours. They should have been on their road at three o'clock; it was now five. Jacob warned them therefore that they must make all speed, and that any one who felt himself unequal to a forced march should stay behind. No one responded to his suggestion, and they were presently on the road.
Passing Lake Meril, with its miniature icebergs, they reached the glacier of the Aletsch and its snow-fields, where the real difficulties and dangers of the ascent were to begin. In this great semicircular space, inclosed by the Jungfrau, the Monch, and the lesser peaks of this mountain group, lies the Aletsch reservoir of snow or neve. As this spot presented a natural pause between the laborious ascent already accomplished and the immense declivities which lay before them yet to be climbed, they named it Le Repos, and halted there for a short rest. Here they left also every needless incumbrance, taking only a little bread and wine, in case of exhaustion, some meteorological instruments, and the inevitable ladder, axe, and ropes of the Alpine climber. On their left, to the west of the amphitheatre, a vast passage opened between the Jungfrau and the Kranzberg, and in this could be distinguished a series of terraces, one above the other. The story is the usual one, of more or less steep slopes, where they sank in the softer snow or cut their steps in the icy surfaces; of open crevasses, crossed by the ladder, or the more dangerous ones, masked by snow, over which they trod cautiously, tied together by the rope. But there was nothing to appall the experienced mountaineer with firm foot and a steady head, until they reached a height where the summit of the Jungfrau detached itself in apparently inaccessible isolation from all beneath or around it. To all but the guides their farther advance seemed blocked by a chaos of precipices, either of snow and ice or of rock. Leuthold remained however quietly confident, telling them he clearly saw the course he meant to follow. It began by an open gulf of unknown depth, though not too wide to be spanned by their ladder twenty-three feet in length. On the other side of this crevasse, and immediately above it, rose an abrupt wall of icy snow. Up this wall Leuthold and another guide led the way, cutting steps as they went. When half way up they lowered the rope, holding one end, while their companions fastened the other to the ladder, so that it served them as a kind of hand-rail, by which to follow. At the top they found themselves on a terrace, beyond which a far more moderate slope led to the Col of Roththal, overlooking the Aletsch valley on one side, the Roththal on the other. From this point the ascent was more and more steep and very slow, as every step had to be cut. Their difficulties were increased, also, by a mist which gathered around them, and by the intense cold. Leuthold kept the party near the border of the ridge, because there the ice yielded more readily to the stroke of the axe; but it put their steadiness of nerve to the greatest test, by keeping the precipice constantly in view, except when hidden by the fog. Indeed, they could drive their alpenstocks through the overhanging rim of frozen snow, and look sheer down through the hole thus made to the amphitheatre below. One of the guides left them, unable longer to endure the sight of these precipices so close at hand. As they neared their goal they feared lest the mist might, at the last, deprive them of the culminating moment for which they had braved such dangers. But suddenly, as if touched by their perseverance, says M. Desor, the veil of fog lifted, and the summit of the Jungfrau, in its final solitude, rose before them. There was still a certain distance to be passed before they actually reached the base of the extreme peak. Here they paused, not without a certain hesitation, for though the summit lay but a few feet above them, they were separated from it by a sharp and seemingly inaccessible ridge. Even Agassiz, who was not easily discouraged, said, as he looked up at this highest point of the fortress they had scaled "We can never reach it." For all answer, Jacob Leuthold, their intrepid guide, flinging down everything which could embarrass his movements, stretched his alpenstock over the ridge as a grappling pole, and, trampling the snow as he went, so as to flatten his giddy path for those who were to follow, was in a moment on the top. To so steep an apex does this famous peak narrow, that but one person can stand on the summit at a time, nor was even this possible till the snow was beaten down. Returning on his steps, Leuthold, whose quiet, unflinching audacity of success was contagious, assisted each one to stand for a few moments where he had stood. The fog, the effect of which they had so much feared, now lent something to the beauty of the view from this sublime foothold. Masses of vapor rolled up from the Roththal on the southwest, but, instead of advancing to envelop them, paused at a little distance arrested by some current from the plain. The temperature being below freezing point, the drops of moisture in this wall of vapor were congealed into ice-crystals, which glittered like gold in the sunlight and gave back all the colors of the rainbow.