TAYMOUTH CASTLE, October 15, 1840.

. . .Lyell has adopted your theory in toto!!! On my showing him a beautiful cluster of moraines, within two miles of his father's house, he instantly accepted it, as solving a host of difficulties that have all his life embarrassed him. And not these only, but similar moraines and detritus of moraines, that cover half of the adjoining counties are explicable on your theory, and he has consented to my proposal that he should immediately lay them all down on a map of the county and describe them in a paper to be read the day after yours at the Geological Society. I propose to give in my adhesion by reading, the same day with yours, as a sequel to your paper, a list of localities where I have observed similar glacial detritus in Scotland, since I left you, and in various parts of England.

There are great reefs of gravel in the limestone valleys of the central bog district of Ireland. They have a distinct name, which I forget. No doubt they are moraines; if you have not, ere you get this, seen one of them, pray do so.* (* Agassiz was then staying at Florence Court, the seat of the Earl of Enniskillen, in County Fermanagh, Ireland. While there he had an opportunity of studying most interesting glacial phenomena. ) But it will not be worth while to go out of your way to see more than one; all the rest must follow as a corollary. I trust you will not fail to be at Edinboro' on the 20th, and at Sir W. Trevelyan's on the 24th. . .

A letter of later date in the same month shows that Agassiz felt his views to be slowly gaining ground among his English friends.

LOUIS AGASSIZ TO SIR PHILIP EGERTON.

LONDON, November 24, 1840.

. . .Our meeting on Wednesday passed off very well; none of my facts were disturbed, though Whewell and Murchison attempted an opposition; but as their objections were far-fetched, they did not produce much effect. I was, however, delighted to have some appearance of serious opposition, because it gave me a chance to insist upon the exactness of my observations, and upon the want of solidity in the objections brought against them. Dr. Buckland was truly eloquent. He has now full possession of this subject; is, indeed, completely master of it.

I am happy to tell you that everything is definitely arranged with Lord Francis,* (* Apropos of the sale of his original drawings of fossil fishes to Lord Francis Egerton.) and that I now feel within myself a courage which doubles my strength. I have just written to thank him. To-morrow I shall devote to the fossils sent me by Lord Enniskillen, a list of which I will forward to you. . .

We append here, a little out of the regular course, a letter from Humboldt, which shows that he too was beginning to look more leniently upon Agassiz's glacial conclusions.

HUMBOLDT TO LOUIS AGASSIZ.

BERLIN, August 15, 1840.

I am the most guilty of mortals, my dear friend. There are not three persons in the world whose remembrance and affection I value more than yours, or for whom I have a warmer love and admiration, and yet I allow half the year to pass without giving you a sign of life, without any expression of my warm gratitude for the magnificent gifts I owe to you.* (* Probably the plates of the "Fresh-Water Fishes" and other illustrated publications.)

I am a little like my republican friend who no longer answers any letters because he does not know where to begin. I receive on an average fifteen hundred letters a year. I never dictate. I hold that resort in horror. How dictate a letter to a scholar for whom one has a real regard? I allow myself to be drawn into answering the persons I know least, whose wrath is the most menacing. My nearer friends (and none are more dear to me than yourself) suffer from my silence. I count with reason upon their indulgence. The tone of your excellent letters shows that I am right. You spoil me. Your letters continue to be always warm and affectionate. I receive few like them. Since two thirds of the letters addressed to me (partly copies of letters written to the king or the ministers) remain unanswered, I am blamed, charged with being a parvenu courtier, an apostate from science. This bitterness of individual claims does not diminish my ardent desire to be useful. I act oftener than I answer. I know that I like to do good, and this consciousness gives me tranquillity in spite of my over burdened life. You are happy, my dear Agassiz, in the more simple and yet truly proud position which you have created for yourself. You ought to take satisfaction in it as the father of a family, as an illustrious savant, as the originator and source of so many new ideas, of so many great and noble conceptions.

Your admirable work on the fossil fishes draws to a close. The last number, so rich in discoveries, and the prospectus, explaining the true state of this vast publication, have soothed all irritation regarding it. It is because I am so attached to you that I rejoice in the calmer atmosphere you have thus established about you. The approaching completion of the fossil fishes delivers me also from the fear that a too great ardor might cause you irreparable losses. You have shown not only what a talent like yours can accomplish, but also how a noble courage can triumph over seemingly insurmountable obstacles.

In what words shall I tell you how greatly our admiration is increased by this new work of yours on the Fresh-Water Fishes? Nothing has appeared more admirable, more perfect in drawing and color. This chromatic lithography resembles nothing we have had thus far. What taste has directed the publication! Then the short descriptions accompanying each plate add singularly to the charm and the enjoyment of this kind of study. Accept my warm thanks, my dear friend. I not only delivered your letter and the copy with it to the king, but I added a short note on the merit of such an undertaking. The counselor of the Royal Cabinet writes me officially that the king has ordered the same number of copies of the Fresh-Water Fishes as of the Fossil Fishes; that is to say, ten copies. M. de Werther has already received the order. This is, to be sure, but a slight help; still, it is all that I have been able to obtain, and these few copies, with the king's name as subscriber, will always be useful to you.

I cannot close this letter without asking your pardon for some expressions, too sharp, perhaps, in my former letters, about your vast geological conceptions. The very exaggeration of my expressions must have shown you how little weight I attached to my objections. . .My desire is always to listen and to learn. Taught from my youth to believe that the organization of past times was somewhat tropical in character, and startled therefore at these glacial interruptions, I cried "Heresy!" at first. But should we not always listen to a friendly voice like yours? I am interested in whatever is printed on these topics; so, if you have published anything at all complete lately on the ensemble of your geological ideas, have the great kindness to send it to me through a book-seller. . .

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.

When all the party were once more assembled at the base of the peak, Jacob, whose resources never failed, served to each one a little wine, and they rested on the snow before beginning their perilous descent. Of living things they saw only a hawk, poised in the air above their heads; of plants, a few lichens, where the surface of the rock was exposed. It was four o'clock in the afternoon before they started on their downward path, turning their faces to the icy slope, and feeling for the steps behind them, some seven hundred in all, which had been cut in ascending. In about an hour they reached the Col of the Roththal, where the greatest difficulties of the ascent had begun and the greatest dangers of the descent were over. So elated were they by the success of the day, and so regardless of lesser perils after those they had passed through, that they were now inclined to hurry forward incautiously. Jacob, prudent when others were rash, as he was bold when others were intimidated, constantly called them to order with his: "Hubschle! nur immer hubschle!" ("Gently! always gently!")

At six o'clock they were once more at Le Repos, having retraced their steps in two hours over a distance which had cost them six in going. Evening was now falling, but daylight was replaced by moonlight, and when they reached the glacier its whole surface shone with a soft silvery lustre, broken here and there by the gigantic shadow of some neighboring mountain thrown black across it. At about nine o'clock, just as they had passed that part of the glacier which was, on account of the frequent crevasses, the most dangerous, they were cheered by the sound of a distant yodel. It was the call of a peasant who had been charged to meet them with provisions, at a certain distance above Lake Meril, in case they should be overcome by hunger and fatigue. The most acceptable thing he brought was his great wooden bucket, filled with fresh milk. The picture of the party, as they stood around him in the moonlight, dipping eagerly into his bucket, and drinking in turn until they had exhausted the supply, is so vivid, that one shares their good spirits and their enjoyment. Thus refreshed, they started on the last stage of their journey, three leagues of which yet lay before them, and at half-past eleven arrived at the chalets of Meril, which they had left at dawn.

On the morrow the party broke up, and Agassiz and Desor, accompanied by their friend, M. Escher de la Linth, returned to the Grimsel, and after a day's rest there repaired once more to the Hotel des Neuchatelois. They remained on the glacier until the 5th of September, spending these few last days in completing their measurements, and in planting the lines of stakes across the glacier, to serve as a means of determining its rate of movement during the year, and the comparative rapidity of that movement at certain fixed points. Thus concluded one of the most eventful seasons Agassiz and his companions had yet passed upon the Alps.* (* Though quoting his exact language only in certain instances, the account of this and other Alpine ascensions described above has been based upon M. E. Desor's "Sejours dans les Glaciers". His very spirited narratives, added to my own recollections of what I had heard from Mr. Agassiz himself on the same subject, have given me my material.—E.C.A.)

CHAPTER 11.

1842-1843: AGE 35-36.

Zoological Work uninterrupted by Glacial Researches. Various Publications. "Nomenclator Zoologicus." "Bibliographia Zoologiae et Geologiae." Correspondence with English Naturalists. Correspondence with Humboldt. Glacial Campaign of 1842. Correspondence with Prince de Canino concerning Journey to United States. Fossil Fishes from the Old Red Sandstone. Glacial Campaign of 1843. Death of Leuthold, the Guide.

Although his glacier work was now so prominent a feature of Agassiz's scientific life, his zoological studies, especially his ichthyological researches, and more especially his work on fossil fishes, went on with little interruption. His publications upon Fossil Mollusks,* (* "Etudes Critiques sur les Mollusques Fossiles" 4 numbers quarto with 100 plates.) upon Tertiary Shells,* (* "Iconographie des Coquilles Tertiaires reputees identiques sur les vivans" 1 number quarto 14 plates.) upon Living and Fossil Echinoderms,* (* "Monographie d'Echinodermes vivans et fossiles" 4 numbers quarto with 37 plates.) with many smaller monographs on special subjects, were undertaken and completed during the most active period of his glacial investigations. More surprising is it to find him, while pursuing new lines of investigation with passionate enthusiasm, engaged at the same time upon works seemingly so dry and tedious as his "Nomenclator Zoologicus," and his "Bibliographia Zoologiae et Geologiae."

The former work, a large quarto volume with an Index,* (* The Index was also published separately as an octavo.) comprised an enumeration of all the genera of the animal kingdom, with the etymology of their names, the names of those who had first proposed them, and the date of their publication. He obtained the cooperation of other naturalists, submitting each class as far as possible for revision to the leaders in their respective departments.

In his letter of presentation to the library of the Neuchatel Academy, addressed to M. le Baron de Chambrier, President of the Academic Council, Agassiz thus describes the Nomenclator.

. . ."Have the kindness to accept for the library of the Academy the fifth number of a work upon the sources of zoological criticism, the publication of which I have just begun. It is a work of patience, demanding long and laborious researches. I had conceived the plan in the first years of my studies, and since then have never lost sight of it. I venture to believe it will be a barrier against the Babel of confusion which tends to overwhelm the domain of zoological synonymy. My book will be called 'Nomenclator Zoologicus.'". . .

The Bibliographia (4 volumes, octavo) was in some measure a complement of the Nomenclator, and contained a list of all the authors named in the latter, with notices of their works. It appeared somewhat later, and was published by the Ray Society in England, in 1848, after Agassiz had left Europe for the United States. The material for this work also had been growing upon his hands for years. Feeling more and more the importance of such a register as a guide for students, he appealed to naturalists in all parts of Europe for information upon the scientific bibliography of their respective countries, and at last succeeded in cataloguing, with such completeness as was possible, all known works and all scattered memoirs on zoology and geology. Unable to publish this costly but unremunerative material, he was delighted to give it up to the Ray Society. The first three volumes were edited with corrections and additions by Mr. H.E. Strickland, who died before the appearance of the fourth volume, which was finally completed under the care of his father-in-law, Sir William Jardine.

The ability, so eminently possessed by Agassiz of dealing with a number of subjects at once, was due to no superficial versatility. To him his work had but one meaning. It was never disconnected in his thought, and therefore he turned from his glaciers to his fossils, and from the fossil to the living world, with the feeling that he was always dealing with kindred problems, bound together by the same laws. Nowhere is this better seen than in the records of the scientific society of Neuchatel, the society he helped to found in the first months of his professorship, and to which he always remained strongly attached, being a constant attendant at its sessions from 1833 to 1846. Here we find him from month to month, with philosophic breadth of thought, treating of animals in their widest relations, or describing minute structural details with the skill of a specialist. He presents organized beings in their geological succession, in their geographical distribution, in their embryonic development. He reviews and remodels laws of classification. Sometimes he illustrates the fossil by the living world, sometimes he finds the key to present phenomena in the remote past. He reconstructs the history of the glacial period, and points to its final chapter in the nearest Alpine valleys, connecting these facts again with like phenomena in distant parts of the globe. But however wide his range and however various his topics, under his touch they are all akin, all coordinate parts of a whole which he strives to understand in its entirety. A few extracts from his correspondence will show him in his different lines of research at this time.

The following letter is from Edward Forbes, one of the earliest explorers of the deep-sea fauna. Agassiz had asked him for some help in his work upon echinoderms.

EDWARD FORBES TO LOUIS AGASSIZ.

21 LOTHIAN ST., EDINBURGH, February 13, 1841.

. . .A letter from you was to me one of the greatest of pleasures, and with great delight (though, I fear, imperfectly) I have executed the commission you gave me. It should have been done much sooner had not the storms been so bad in the sea near this that, until three days ago, I was not able to procure a living sea-urchin from which to make the drawings required. . .You have made all the geologists glacier-mad here, and they are turning Great Britain into an ice-house. Some amusing and very absurd attempts at opposition to your views have been made by one or two pseudo-geologists; among others, poor—, who has read a paper at the Royal Society here, maintaining that all the appearances you refer to glaciers were caused by blocks of ice which floated this way in the Deluge! and that the fossils of the pleistocene strata were mollusks, etc., which, climbing upon the ice-blocks, were carried to warmer seas against their will!! To my mind, one of the best proofs of the truth of your views lies in the decidedly arctic character of the pleistocene fauna, which must be referred to the glacier time, and by such reference is easily understood. I mean during the summer to collect data on that point, in order to present a mass of geological proofs of your theory.

Dr. Traill tells me you are proposing to visit England again during the coming summer. If you do, I hope we shall meet, when I shall have many things to show you, which time did not permit when you were here. I look anxiously for the forth-coming number of your history of the Echinodermata. . .

FROM SIR RODERICK MURCHISON.

June 13, 1842.

. . .Your letters have given me great pleasure: first, in assuring me that your zeal in ichthyology is undiminished, and that you are about to give such striking proofs of it to the British Association; and next that you still pursue with enthusiasm your admirable researches upon the glaciers. I should be charmed to put myself under your guidance for a walk on the glaciers of the Aar, but I hardly dare promise it yet. . .Even were I to make every haste, I doubt if it be possible to reach your Swiss meeting in time. It is just possible that I may find you in your glacial cantonment after your return, but even this will depend upon circumstances over which I have no control.

I send this letter to you by my friend, Admiral Sir Charles Malcolm, who passes through Neuchatel on his way to Geneva. Accompanying it is a copy of my last discourse, which I request you to accept and to read all parts of it. You will see that I have grappled honestly and according to my own faith with your ice, but have never lost sight of your great merit. My concluding paragraph will convince you and all your friends that if I am wrong it is not from any preconceived notions, but only because I judge from what you will call incomplete evidence. Your "Venez voir!" still sounds in my ears. . .

Murchison remained for many years an opponent of the glacial theory in its larger application. In the discourse to which the above letter makes allusion (Address at the Anniversary Meeting of the Geological Society of London, 1842.* (* Extract from Report in volume 33 of the "Edinburgh New Philosophical Journal".)) is this passage: "Once grant to Agassiz that his deepest valleys of Switzerland, such as the enormous Lake of Geneva, were formerly filled with snow and ice, and I see no stopping place. From that hypothesis you may proceed to fill the Baltic and the northern seas, cover southern England and half of Germany and Russia with similar icy sheets, on the surfaces of which all the northern boulders might have been shot off. So long as the greater number of the practical geologists of Europe are opposed to the wide extension of a terrestrial glacial theory, there can be little risk that such a doctrine should take too deep a hold of the mind. . . The existence of glaciers in Scotland and England (I mean in the Alpine sense) is not, at all events, established to the satisfaction of what I believe to be by far the greater number of British geologists."

Twenty years later, with rare candor, Murchison wrote to Agassiz as follows; by its connection, though not by its date, the extract is in place here: "I send you my last anniversary address, which I wrote entirely myself; and I beg you to believe that in the part of it that refers to the glacial period, and to Europe as it was geographically, I have had the sincerest pleasure in avowing that I was wrong in opposing as I did your grand and original idea of my native mountains. Yes! I am now convinced that glaciers did descend from the mountains to the plains as they do now in Greenland."

During the summer of 1842, at about the same date with Murchison's letter disclaiming the glacial theory, Agassiz received, on the other hand, a new evidence, and one which must have given him especial pleasure, of the favorable impression his views were making in some quarters in England.

FROM DR. BUCKLAND.

OXFORD, July 22, 1842.

You will, I am sure, rejoice with me at the adhesion of C. Darwin to the doctrine of ancient glaciers in North Wales, of which I send you a copy, and which was communicated to me by Dr. Tritten, during the late meeting at Manchester, in time to be quoted by me versus Murchison, when he was proclaiming the exclusive agency of floating icebergs in drifting erratic blocks and making scratched and polished surfaces. It has raised the glacial theory fifty per cent, as far as relates to glaciers descending inclined valleys; but Hopkins and the Cantabrigians are still as obstinate as ever against allowing the power of expansion to move ice along great distances on horizontal surfaces. . .

The following is the letter referred to above.

C. DARWIN TO DR. TRITTEN.

Yesterday (and the previous days) I had some most interesting work in examining the marks left by EXTINCT glaciers. I assure you, an extinct volcano could hardly leave more evident traces of its activity and vast powers. I found one with the lateral moraine quite perfect, which Dr. Buckland did not see. Pray if you have any communication with Dr. Buckland give him my warmest thanks for having guided me, through the published abstract of his memoir, to scenes, and made me understand them, which have given me more delight than I almost remember to have experienced since I first saw an extinct crater. The valley about here and the site of the inn at which I am now writing must once have been covered by at least 800 or 1,000 feet in thickness of solid ice! Eleven years ago I spent a whole day in the valley where yesterday everything but the ice of the glaciers was palpably clear to me, and I then saw nothing but plain water and bare rock. These glaciers have been grand agencies. I am the more pleased with what I have seen in North Wales, as it convinces me that my view of the distribution of the boulders on the South American plains, as effected by floating ice, is correct. I am also more convinced that the valleys of Glen Roy and the neighboring parts of Scotland have been occupied by arms of the sea, and very likely (for in that point I cannot, of course, doubt Agassiz and Buckland) by glaciers also.

It continued to be a grief to Agassiz that Humboldt, the oldest of all his scientific friends, and the one whose opinion he most reverenced, still remained incredulous. Humboldt's letters show that Agassiz did not willingly renounce the hope of making him a convert. Agassiz's own letters to Humboldt are missing from this time onward. Overwhelmed with occupation, and more at his ease in his relations with the older scientific men, he had ceased to make the rough drafts in which his earlier correspondence is recorded.

HUMBOLDT TO AGASSIZ.

BERLIN, March 2, 1842.

. . .When one has been so long separated, even accidentally, from a friend as I have been from you, my dear Agassiz, it is difficult to find beginning or end to a letter. The kindly remembrance which you send me is evidence that my long silence has not seemed strange to you. . .It would be wasting words to tell you how I have been prevented, by the distractions of my life, always increasing with old age, from acknowledging the admirable things received from you, —upon living and fossil fishes, echinoderms, and glaciers. My admiration of your boundless activity, of your beautiful intellectual life, increases with every year. This admiration for your work and your bold excursions is based upon the most careful reading of all the views and investigations, for which I have to thank you. This very week I have read with great satisfaction your truly philosophical address, and your long treatise in Cotta's fourth "Jahresschrift." Even L. von Buch confessed that the first half of your treatise, the living presentation of the succession of organized beings, was full of truth, sagacity, and novelty.

I in no way reproach you, my dear friend, for the urgent desire expressed in all your letters, that your oldest friends should accept your comprehensive geological view of your ice-period. It is very noble and natural to wish that what has impressed us as true should also be recognized by those we love. . .I believe I have read and compared all that has been written for and against the ice-period, and also upon the transportation of boulders, whether pushed along or carried by floods or gliding over slopes. My own opinion, as you know, can have no weight or authority, since I have not myself seen the most decisive points. Indeed I am, perhaps wrongly, inclined to look upon all geological theories as having their being in a mythical region, in which, with the progress of physics, the phantasms are modified century by century. But the "elephants caught in the ice," and Cuvier's "instantaneous change of climate," seem to me no more intelligible today than when I wrote my Asiatic fragments. According to all that we know of the decrease of heat in the earth, I cannot understand such a change of temperature in a space of time which does not also allow for the decaying of flesh. I understand much better how wolves, hares, and dogs, should they fall to-day into clefts of the frozen regions of Northern Siberia (and the so-called "elephant-ice" is in plain prose only porphyritic drift mixed with ice-crystals, true drift material), might retain their flesh and muscles. . .But I am only a grumbling rebellious subject in your kingdom. . .Do not be vexed with a friend who is more than ever impressed with your services to geology, your philosophical views of nature, your profound knowledge of organized beings. . .

With old attachment and the warmest friendship, your

A. DE HUMBOLDT.

In the same strain is this extract from another letter of Humboldt's, written two or three months later.

. . ."'Grace from on high,' says Madame de Sevigne, 'comes slowly.' I especially desire it for the glacial period and for that fatal cap of ice which frightens me, child of the equator that I am. My heresy, of little importance, since I have seen nothing, does not, I assure you, my dear Agassiz, diminish my ardent desire that all your observations should be published. . .I rejoice in the good news you give me of the fishes. I should pain you did I add that this work of yours, by the light it has shed on the organic development of animals, makes the true foundation of your glory.". . .

LOUIS AGASSIZ TO SIR PHILIP EGERTON.

NEUCHATEL, June, 1842.

. . .I am hard at work on the fishes of the "Old Red," and will send you at Manchester a part at least of the plates, with a general summary of the species of that formation. I aim to finish the work with such care that it shall mark a sensible advance in ichthyology. I hope it will satisfy you. . .You ask me how I intend to finish my Fossil Fishes? As follows: As soon as the number on the species of the "Old Red" is finished, I shall complete the general outline of the work as I did with volume 4, in order that the arrangement and character of all the families in the four orders may be studied in their zoological affinities, with their genera and principal species. But as this outline can no longer contain the innumerable species now known to me, I take up monographically the species from the different geological formations in the order of the deposits, and publish as many supplements as there are great formations rich in fossil fishes. I shall limit myself to the species described in the body of the work, merely adding the description of the new species in each deposit, and such additions as I may have to make for those already known. In this way, those who wish to study fossil fishes from the zoological stand-point can turn to the work in the original form, while those who wish to study them in their geological relations can confine themselves to the supplements. By means of double registers at the end of each volume, these two distinct parts of the work will be again united as a complete whole. This is the only plan I have been able to devise by which I could publish in succession all my materials without burdening my first subscribers, who will thus be free to accept the supplements or not, as they prefer. Should you have occasion to mention this arrangement to the friends of fossil ichthyology, pray do so; it seems to me for the interest of the matter that it should be known. . .I propose to resume with new zeal my researches upon the fossil fishes as soon as I return from an excursion I wish to make in July and August to the glacier of the Aar, where I hope, by a last visit this year, to conclude my labors on this subject. You will be glad to learn that the beautiful barometer you gave me has been my faithful companion in the Alps. . .I have the pleasure to tell you that the King of Prussia has made me a handsome gift of nearly 200 pounds for the continuance of my glacial work. I feel, therefore, the greater certainty of completing what remains for me to do. . .

The campaign of 1842 opened on the 4th of July. The boulder had ceased to be a safe shelter, and was replaced by a rough frame cabin covered with canvas. If the party had some regrets in leaving their picturesque hut beneath the rock, the greater comfort of the new abode consoled them. It had several divisions. A sleeping-place for the guides and workmen was partitioned off from a middle room occupied by Agassiz and his friends, while the front space served as dining-room, sitting-room, and laboratory. This outer apartment boasted a table and one or two benches; even a couple of chairs were kept as seats of honor for occasional guests. A shelf against the wall and a few pegs accommodated books, instruments, coats, etc., and a plank floor, on which to spread their blankets at night, was a good exchange for the frozen surface of the glacier.* (* In bidding farewell to the boulder which had been the first "Hotel des Neuchatelois" we may add a word of its farther fortunes. It had begun to split in 1841, and was completely rent asunder in 1844, after which frost and rain completed its dismemberment. Strange to say, during the last summer (1884) certain fragments of the mass have been found, inscribed with the names of some of the party; one of the blocks bearing beside names, the mark "Number 2". The account says "The middle stone, the one numbered 2, was at the intersecting point of two lines drawn from the Pavilion Dollfuss to the Scheuchzerhorn on the one part, and from the Rothhorn to the Thierberg on the other." According to the measurements taken by Agassiz, the Hotel des Neuchatelois in 1840 stood at 797 metres from the promontory of Abschwung. We are thus enabled, by referring to the large glacier map of Wild and Stengel, to compare the present with the then position of the stone, and thereby ascertain the progress of the glacier since the time in question. Thus the boulder still contributes something toward the sequel of the work begun by those who once found shelter beneath it.—E.C.A.)

Mr. Wild, an engineer of known ability, was now a member of their party, as a topographical survey was to be one of the chief objects of the summer's work. The results of this survey, which was continued during two summers, are embodied in the map accompanying Agassiz's "Systeme Glaciaire." Experiments upon the extent and connection of the net-work of capillary fissures that admitted water into the interior of the glaciers, occupied Agassiz's own attention during a great part of the summer. In order to ascertain this, colored liquids were introduced into the glacier by means of boring, and it was found that they threaded their way through the mass of the ice and reappeared at lower points with astonishing rapidity. A gallery was cut at a depth of ten metres below the surface, through a wall of ice intervening between two crevasses. The colored liquid poured into a hole above soon appeared on the ceiling of the gallery. The experimenters were surprised to find that at night the same result was obtained, and that the liquid penetrated from the surface to the roof of the gallery even more quickly than during the day. This was explained by the fact that the fissures were then free from any moisture arising from surface melting, so that the passage through them was unimpeded.* (* Distrust has been thrown upon these results by the failure of more recent attempts to repeat the same experiments. In reference to this, Agassiz himself says "The infiltration has been denied in consequence of the failure of some experiments in which an attempt was made to introduce colored fluids into the glacier. To this I can only answer that I succeeded completely myself in the self-same experiment which a later investigator found impracticable, and that I see no reason why the failure of the latter attempt should cast a doubt upon the success of the former. The explanation of the difference in the result may perhaps be found in the fact that as a sponge gorged with water can admit no more fluid than it already contains, so the glacier, under certain circumstances, and especially at noonday in summer, may be so soaked with water that all attempts to pour colored fluids into it would necessarily fail."—See "Geological Sketches" by L. Agassiz, page 236.)

The comparative rate of advance in the different parts of the glacier was ascertained this summer with greater precision than before. The rows of stakes planted in a straight line across the glacier by Agassiz and Escher de la Linth, in the previous September, now described a crescent with the curve turned toward the terminus of the glacier, showing, contrary to the expectation of Agassiz, that the centre moved faster than the sides. The correspondence of the curve in the stratification with that of the line of stakes confirmed this result. The study of the stratification of the snow was a marked feature of the season's work, and Agassiz believed, as will be seen by a later letter, that he had established this fact of glacial structure beyond a doubt.

The origin and mode of formation of the crevasses also especially occupied the observers. On the 7th of August, Agassiz had an opportunity of watching this phenomenon in its initiation. Attracted to a certain spot on the glacier by a commotion among his workmen, he found them alarmed at the singular noises and movements in the ice. "I heard," he says, "at a little distance a sound like the simultaneous discharge of fire-arms; hurrying in the direction of the noise, it was repeated under my feet with a movement like that of a slight earthquake; the ground seemed to shift and give way under me, but now the sound differed from the preceding, and resembled a crumbling of rocks, without, however, any perceptible sinking of the surface. The glacier actually trembled, nevertheless; for a block of granite three feet in diameter, perched on a pedestal two feet high, suddenly fell down. At the same instant a crack opened between my feet and ran rapidly across the glacier in a straight line."* (* Extract from a letter of Louis Agassiz to M. Arago dated from the Hotel des Neuchatelois, Glacier of the Aar, August 7, 1842.) On this occasion Agassiz saw three crevasses formed in an hour and a half, and heard others opening at a greater distance from him. He counted eight new fissures in a space of one hundred and twenty-five feet. The phenomenon continued throughout the evening, and recurred, though with less frequency, during the night. The cracks were narrow, the largest an inch and a half in width, and their great depth was proved by the rapidity with which they drained any standing water in their immediate vicinity. "A boring-hole," says Agassiz, "one hundred and thirty feet deep and six inches in diameter, full of water, was completely emptied in a few minutes, showing that these narrow cracks penetrated to great depths."

The summer's work included observations also on the comparative movement of the glacier during the day and night, on the surface waste of the mass, its reparation, on the neve and snow of the upper regions, on the meridian holes, the sun-dials of the glaciers, as they have been called.* (* "Here and there on the glacier there are patches of loose material, dust, sand, or gravel, accumulated by diminutive water-rills and small enough to become heated during the day. They will, of course, be warmed first on their eastern side, then still more powerfully on their southern side, and, in the afternoon, with less force again, on their western side, while the northern side will remain comparatively cool. Thus around more than half of their circumference they melt the ice in a semicircle, and the glacier is covered with little crescent-shaped troughs of this description, with a steep wall on one side and a shallow one on the other, and a little heap of loose materials in the bottom. They are the sun-dials of the glacier, recording the hour by the advance of the sun's rays upon them."—" Geological Sketches" by L. Agassiz page 293.) On the whole, the most important result of the campaign was the topographical survey of the glacier, recorded in the map published in Agassiz's second work on the glacier.

At about this time there begin to be occasional references in his correspondence to a journey of exploration in the United States. Especially was this plan in frequent discussion between him and Charles Bonaparte, Prince of Canino, a naturalist almost as ardent as himself, with whom he had long been in intimate scientific correspondence. In April, 1842, the prince writes him: "I indulge myself in dreaming of the journey to America in which you have promised to accompany me. What a relaxation! and at the same time what an amount of useful work!" Again, a few months later, "You must keep me well advised of your plans, and I, in my turn, will try so to arrange my affairs as to find myself free in the spring of 1844 for a voyage, the chief object of which will be to show my oldest son the country where he was born, and where man may develop free of shackles. The mere anticipation of this journey is delightful to me, since I shall have you at my side, and may thus feel sure that it will make an epoch in science." This letter is answered from the glacier; the first part refers to the Nomenclator, in regard to which he often consulted the prince.

LOUIS AGASSIZ TO THE PRINCE OF CANINO.

GLACIER OF THE AAR, September 1, 1842.

. . .I thank you most sincerely for the pains you have so kindly taken with my proof, and for pointing out the faults and omissions you have noticed in my register of birds. I made the corrections at once, and have taken the liberty of mentioning on the cover of this number the share you have consented to take in my Nomenclator. I shall try to do better and better in the successive classes, but you well know the impossibility of avoiding grave errors in such a work, and that they can be wholly weeded out only in a second and third edition. I should have written sooner in answer to your last, had not your letter reached me on the Glacier of the Aar, where I have been since the beginning of July, following up observations, the results of which become every day more important and more convincing. The most striking fact, one which I think I have placed beyond the reach of doubt, is the primitive stratification of the neve, or fields of snow,—stratified from the higher regions across the whole course of the glacier to its lower extremity. I have prepared a general map, with transverse sections, showing how the layers lift themselves on the borders of the glacier and also at their junction, where two glaciers meet at the outlet of adjoining valleys; and how, also, the waving lines formed by the layers on the surface change to sharper concentric curves with a marked axis, as the glacier descends to lower levels. For a full demonstration of the matter, I ought to send you my map and plans, of which I have, as yet, no duplicates; but the fact is incontestable, and you will oblige me by announcing it in the geological section at Padua. M. Charpentier, who is going to your meeting, will contest it, but you can tell him from me that it is as evident as the stratification of the Neptunic rocks. To see and understand it fully, however, one must stand well above the glacier, so as to command the surface as a whole in one view. I would add that I am not now alluding to the blue and white bands in the ice of which I spoke to you last year; this is a quite distinct phenomenon.

I wish I could accept your kind invitation, but until I have gone to the bottom of the glacier question and terminated my "Fossil Fishes," I do not venture to move. It is no light task to finish all this before our long journey, to which I look forward, as it draws nearer, with a constantly increasing interest. I am very sorry not to join you at Florence. It would have been a great pleasure for me to visit the collections of northern Italy in your company. . .I write you on a snowy day, which keeps me a prisoner in my tent; it is so cold that I can hardly hold my pen, and the water froze at my bedside last night. The greatest privation is, however, the lack of fruit and vegetables. Hardly a potato once a fortnight, but always and every day, morning and night, mutton, everlasting mutton, and rice soup. As early as the end of July we were caught for three days by the snow; I fear I shall be forced to break up our encampment next week without having finished my work. What a contrast between this life and that of the plain! I am afraid my letter may be long on the road before reaching the mail, and I pause here that I may not miss the chance of forwarding it by a man who has just arrived with provisions and is about to return to the hospice of the Grimsel, where some trustworthy guide will undertake to deliver it at the first post-office.

No sooner is Agassiz returned from the glacier than we meet him again in the domain of his fossil fishes.

LOUIS AGASSIZ TO SIR PHILIP EGERTON.

NEUCHATEL, December 15, 1842.

. . .In the last few months I have made an important step in the identification of fossil fishes. The happy idea occurred to me of applying the microscope to the study of fragments of their bones, especially those of the head, and I have found in their structure modifications as remarkable and as numerous as those which Mr. Owen discovered in the structure of teeth. Here there is a vast new field to explore. I have already applied it to the identification of the fossil fishes in the Old Red of Russia sent me for that purpose by Mr. Murchison. You will find more ample details about it in my report to him. I congratulate myself doubly on the results; first, because of their great importance in paleontology, and also because they will draw more closely my relations with Mr. Owen, whom I always rejoice to meet on the same path with myself, and whom I believe incapable of jealousy in such matters. . .The only point indeed, on which I think I may have a little friendly difference with him, is concerning the genus Labyrinthodon, which I am firmly resolved, on proofs that seem to me conclusive, to claim for the class of fishes.* (* On seeing Owen's evidence some years later, Agassiz at once acknowledged himself mistaken on this point. ) As soon as I have time I will write to Mr. Owen, but this need not prevent you from speaking to him on the subject if you have an early opportunity to do so. I am now exclusively occupied with the fossil fishes, which at any cost I wish to finish this winter. . . Before even returning to my glacier work, I will finish my monograph of the Old Red, so that you may present it at the Cork meeting, which it will be impossible for me to attend. . .I am infinitely grateful to you and Lord Enniskillen for your willingness to trust your Sheppy fishes to me; I shall thus be prepared in advance for a strict determination of these fossils. Having them for some time before my eyes, I shall become familiar with all the details. When I know them thoroughly, and have compared them with the collections of skeletons in the Museums of Paris, of Leyden, of Berlin, and of Halle, I will then come to England to see what there may be in other collections which I cannot have at my disposal here.

The winter of 1843, apart from his duties as professor, was devoted to the completion of the various zoological works on which he was engaged, and to the revision of materials he had brought back from the glacier. His habits with reference to physical exercise were very irregular. He passed at once from the life of the mountaineer to that of the closet student. After weeks spent on the snow and ice of the glacier, constantly on foot and in the open air, he would shut himself up for a still longer time in his laboratory, motionless for hours at his microscope by day, and writing far into the night, rarely leaving his work till long after midnight. He was also forced at this time to press forward his publications in the hope that he might have some return for the sums he had expended upon them. This was indeed a very anxious period of his life. He could never be brought to believe that purely intellectual aims were not also financially sound, and his lithographic establishment, his glacier work, and his costly researches in zoology had proved far beyond his means. The prophecies of his old friend Humboldt were coming true. He was entangled in obligations, and crushed under the weight of his own undertakings. He began to doubt the possibility of carrying out his plan of a scientific journey to the United States.

AGASSIZ TO THE PRINCE OF CANINO.

NEUCHATEL, April, 1843.

. . .I have worked like a slave all winter to finish my fossil fishes; you will presently receive my fifteenth and sixteenth numbers, forwarded two days since, with more than forty pages of text, containing many new observations. I shall allow myself no interruption until this work is finished, hoping thereby to obtain a little freedom, for if my position here is not changed I shall be forced to seek the means of existence elsewhere. Meantime, extravagant projects present themselves, as is apt to be the case when one is in difficulties. That of accompanying you to the United States was so tempting, that I am bitterly disappointed to think that its execution becomes impossible in my present circumstances. All my projects for further publications must also be adjourned, or perhaps renounced. . .Possibly, when my work on the fossil fishes is completed, the sale of some additional copies may help me to rise again. And yet I have not much hope of this, since all the attempts of my friends to obtain subscriptions for me in France and Russia have failed: because the French government takes no interest in what is done out of Paris; and in Russia such researches, having little direct utility, are looked upon with indifference. Do you think any position would be open to me in the United States, where I might earn enough to enable me to continue the publication of my unhappy books; which never pay their way because they do not meet the wants of the world?. . .

In the following July we find him again upon the glacier. But the campaign of 1843 opened sadly for the glacial party. Arriving at Meiringen they heard that Jacob Leuthold was ill and would probably be unable to accompany them. They went to his house, and found him, indeed, the ghost of his former self, apparently in a rapid decline. Nevertheless, he welcomed them gladly to his humble home, and would have kept them for some refreshment. Fearing to fatigue him, however, they stayed but a few moments. As they left, one of the party pointed to the mountains, adding a hope that he might soon join them. His eyes filled with tears; it was his only answer, and he died three days later. He was but thirty-seven years of age, and at that time the most intrepid and the most intelligent of the Oberland guides. His death was felt as a personal grief by the band of workers whose steps he had for years guided over the most difficult Alpine passes.

The summer's work continued and completed that of the last season. On leaving the glacier the year before they had marked a network of loose boulders, such as travel with the ice, and also a number of fixed points in the valley walls, comparing and registering their distance from each other. They had also sunk a line of stakes across the glacier. The change in the relative position of the two sets of signals and the curve in their line of stakes gave them, self-recorded, as it were, the rate of advance of the glacier as a whole, and also the comparative rate of progression in its different parts. Great pains was also taken during the summer to measure the advance in every twenty-four hours, as well as to compare the diurnal with the nocturnal movement, and to ascertain the amount of surface waste. The season was an unfavorable one, beginning so late and continuing so cold that the period of work was shortened.

CHAPTER 12.

1843-1846: AGE 36-39.

Completion of Fossil Fishes. Followed by Fossil Fishes of the Old Red Sandstone. Review of the Later Work. Identification of Fishes by the Skull. Renewed Correspondence with Prince Canino about Journey to the United States. Change of Plan owing to the Interest of the King of Prussia in the Expedition. Correspondence between Professor Sedgwick and Agassiz on Development Theory. Final Scientific Work in Neuchatel and Paris. Publication of "Systeme Glaciaire." Short Stay in England. Farewell Letter from Humboldt. Sails for United States.

In 1843 the "Recherches sur les Poissons Fossiles" was completed, and fast upon its footsteps, in 1844, followed the author's "Monograph on the Fossil Fishes of the Old Red Sandstone, or the Devonian System of Great Britain and Russia," a large quarto volume of text, accompanied by forty-one plates. Nothing in his paleontological studies ever interested Agassiz more than this curious fauna of the Old Red, so strange in its combinations that even well-informed naturalists had attributed its fossil remains to various classes of the animal kingdom in turn, and, indeed, long remained in doubt as to their true nature. Agassiz says himself in his Preface: "I can never forget the impression produced upon me by the sight of these creatures, furnished with appendages resembling wings, yet belonging, as I had satisfied myself, to the class of fishes. Here was a type entirely new to us, about to reenter (for the first time since it had ceased to exist) the series of beings; nor could anything, thus far revealed from extinct creations, have led us to anticipate its existence. So true is it that observation alone is a safe guide to the laws of development of organized beings, and that we must be on our guard against all those systems of transformation of species so lightly invented by the imagination."

The author goes on to state that the discovery of these fossils was mainly due to Hugh Miller, and that his own work had been confined to the identification of their character and the determination of their relations to the already known fossil fishes. This work, upon a type so extraordinary, implied, however, innumerable and reiterated comparisons, and a minute study of the least fragments of the remains which could be procured. The materials were chiefly obtained in Scotland; but Sir Roderick Murchison also contributed his own collection from the Old Red of Russia, and various other specimens from the same locality. Not only on account of their peculiar structure were the fishes of the Old Red interesting to Agassiz, but also because, with this fauna, the vertebrate type took its place for the first time in what were then supposed to be the most ancient fossiliferous beds. When Agassiz first began his researches on fossil fishes, no vertebrate form had been discovered below the coal. The occurrence of fishes in the Devonian and Silurian beds threw the vertebrate type back, as he believed, into line with all the invertebrate classes, and seemed to him to show that the four great types of the animal kingdom, Radiates, Mollusks, Articulates, and Vertebrates, had appeared together.* (* Introduction to the "Poissons Fossiles de Vieux Gres Rouge" page 22.) "It is henceforth demonstrated," says Agassiz, "that the fishes were included in the plan of the first organic combinations which made the point of departure for all the living inhabitants of our globe in the series of time."

In his opinion this simultaneity of appearance, as well as the richness and variety displayed by invertebrate classes from the beginning, made it* (* Introduction to the "Poissons Fossiles du Vieux Gres Rouge" page 21.) "impossible to refer the first inhabitants of the earth to a few stocks, subsequently differentiated under the influence of external conditions of existence.". . .He adds:* (* Introduction to the "Poissons Fossiles de Vieux Gres Rouge" page 24.) "I have elsewhere presented my views upon the development through which the successive creations have passed during the history of our planet. But what I wish to prove here, by a careful discussion of the facts reported in the following pages, is the truth of the law now so clearly demonstrated in the series of vertebrates, that the successive creations have undergone phases of development analogous to those of the embryo in its growth and similar to the gradations shown by the present creation in the ascending series, which it presents as a whole. One may consider it as henceforth proved that the embryo of the fish during its development, the class of fishes as it at present exists in its numerous families, and the type of fish in its planetary history, exhibit analogous phases through which one may follow the same creative thought like a guiding thread in the study of the connection between organized beings." Following this comparison closely, he shows how the early embryonic condition of the present fishes is recalled by the general disposition of the fins in the fishes of the Old Red Sandstone, and especially by the caudal fin, making the unevenly lobed tail, so characteristic of these ancient forms. This so called heterocercal tail is only known to exist, as a permanent adult feature, in the sturgeons of to-day. The form of the head and the position of the mouth and eyes in the fishes of the Old Red were also shown to be analogous with embryonic phases of our present fishes. From these analogies, and also from the ascendancy of fishes as the only known vertebrate, and therefore as the highest type in those ancient deposits, Agassiz considered this fauna as representing "the embryonic age of the reign of fishes;" and he sums up his results in conclusion in the following words: "The facts, taken as a whole, seem to me to show, not only that the fishes of the Old Red constitute an independent fauna, distinct from those of other deposits, but that they also represent in their organization the most remarkable analogy with the first phases of embryonic development in the bony fishes of our epoch, and a no less marked parallelism with the lower degrees of certain types of the class as it now exists on the surface of the earth."

It has been said by one of the biographers of Agassiz,* (* "Louis Agassiz: Notice biographique" par Ernest Favre.) in reference to this work upon the fishes of the Old Red Sandstone: "It is difficult to understand why the results of these admirable researches, and of later ones made by him, did not in themselves lead him to support the theory of transformation, of which they seem the natural consequence." It is true that except for the frequent allusion to a creative thought or plan, this introduction to the Fishes of the Old Red might seem to be written by an advocate of the development theory rather than by its most determined opponent, so much does it deal with laws of the organic world, now used in support of evolution. These comprehensive laws, announced by Agassiz in his "Poissons Fossiles," and afterward constantly reiterated by him, have indeed been adopted by the writers on evolution, though with a wholly different interpretation. No one saw more clearly than Agassiz the relation which he first pointed out, between the succession of animals of the same type in time and the phases of their embryonic growth to-day, and he often said, in his lectures, "the history of the individual is the history of the type." But the coincidence between the geological succession, the embryonic development, the zoological gradation, and the geographical distribution of animals in the past and the present, rested, according to his belief, upon an intellectual coherence and not upon a material connection. So, also, the variability, as well as the constancy, of organized beings, at once so plastic and so inflexible, seemed to him controlled by something more than the mechanism of self-adjusting forces. In this conviction he remained unshaken all his life, although the development theory came up for discussion under so many various aspects during that time. His views are now in the descending scale; but to give them less than their real prominence here would be to deprive his scientific career of its true basis. Belief in a Creator was the keynote of his study of nature.

In summing up the comprehensive results of Agassiz's paleontological researches, and especially of his "Fossil Fishes," Arnold Guyot says:* (* See "Biographical Memoir of Louis Agassiz" page 28.)—"Whatever be the opinions which many may entertain as to the interpretation of some of these generalizations, the vast importance of these results of Agassiz's studies may be appreciated by the incontestable fact, that nearly all the questions which modern paleontology has treated are here raised and in great measure solved. They already form a code of general laws which has become a foundation for the geological history of the life-system, and which the subsequent investigations of science have only modified and extended, not destroyed. Nowhere did the mind of Agassiz show more power of generalization, more vigor, or more originality. The discovery of these great truths is truly his work; he derived them immediately from nature by his own observations. Hence it is that all his later zoological investigations tend to a common aim, namely, to give by farther studies, equally conscientious but more extensive, a broader and more solid basis to those laws which he had read in nature and which he had proclaimed at that early date in his immortal work, 'Poissons Fossiles.' Let us not be astonished that he should have remained faithful to these views to the end of his life. It is because he had SEEN that he BELIEVED, and such a faith is not easily shaken by new hypotheses."

LOUIS AGASSIZ TO SIR PHILIP EGERTON.

NEUCHATEL, September 7, 1844.

. . .I write in all haste to ask for any address to which I can safely forward my report on the Sheppy fishes, so that they may arrive without fail in time for the meeting at York. Since my last letter I have made progress in this kind of research. I have sacrificed all my duplicates of our present fishes to furnish skeletons. I have prepared more than a hundred since I last wrote you, and I can now determine the family, and even the genus, simply by seeing the skull. There remains nothing impossible now in the determination of fishes, and if I can obtain certain exotic genera, which I have not as yet, I can make an osteology of fishes as complete as that which we possess for the other classes of vertebrates. Every family has its special type of skull. All this is extremely interesting. I have already corrected a mass of inaccurate identifications established upon external characters; and as for fossils, I have recognized and characterized seventeen new genera among the less perfect undetermined specimens you have sent me. Several families appear now for the first time among the fossils. I have been able to determine to what family all the doubtful genera belong; indeed Sheppy will prove as rich in species as Mont Bolca. When you see your specimens again you will hardly recognize them, they are so changed; I have chiseled and cleaned them, until they are almost like anatomical preparations. Try to procure as many more specimens as possible and send them to me. I cannot stir from Neuchatel, now that I am so fully in the spirit of work, and besides it would be a useless expense. . .You will receive with my report the three numbers which complete my monograph of the Fishes of the Old Red. I feel sure, in advance, that you will be satisfied with them. . .

SIR PHILIP EGERTON TO LOUIS AGASSIZ.

TOLLY HOUSE, ALNESS, ROSS-SHIRE. September 15, 1844.

. . .I have only this day received your letter of the 6th, and I fear much you will scarcely receive this in time to make it available. I shall not be able to reach York for the commencement of the meeting, but hope to be there on Saturday, September 28th. A parcel will reach me in the shortest possible time addressed Sir P. Egerton, Donnington Rectory, York. I am delighted with the bright results of your comparison of the Sheppy fossils with recent forms. You appear to have opened out an entirely new field of investigation, likely to be productive of most brilliant results. Should any accident delay the arrival of your monograph for the York meeting, I shall make a point of communicating to our scientific friends the contents of your letter, as I know they will rejoice to hear of the progress of fossil ichthyology in your masterly hands. When next you come, I wish you could spend a few days here. We are surrounded on all sides by the debris of the moraines of the ancient glaciers that descended the flank of Ben Wyvis, and I think you would find much to interest you in tracing their relations. We have also the Cromarty Fish-beds within a few miles, and many other objects of geological interest. . .I shall see Lord Enniskillen at York, and will tell him of your success. We shall, of course, procure all the Sheppy fish we can either by purchase or exchange. . .

The pressure of work upon his various publications detained Agassiz at home during the summer of 1844. For the first time he was unable to make one of the glacial party this year, but the work was carried on uninterruptedly, and the results reported to him. Meantime his contemplated journey to the United States flitted constantly before him.

AGASSIZ TO THE PRINCE OF CANINO.

NEUCHATEL, November 19, 1844.

. . .Your idea of an illustrated American ichthyology is admirable. But for that we ought to have with us an artist clever enough to paint fishes rapidly from the life. Work but half done is no longer permissible in our days. . .In this matter I think there is a justice due to Rafinesque. However poor his descriptions, he nevertheless first recognized the necessity of multiplying genera in ichthyology, and that at a time when the thing was far more difficult than now. Several of his genera have even the priority over those now accepted, and I think in the United States it would be easier than elsewhere to find again a part of the materials on which he worked. We must not neglect from this time forth to ask Americans to put us in the way of extending this work throughout North America. If you accept me for your collaborator, I will at once do all that I can on my side to bring together notes and specimens. I will write to several naturalists in the United States, and tell them that as I am to accompany you on your voyage I should be glad to know in advance what they have done in ichthyology, so that we may be the better prepared to profit by our short sojourn in their country. However, I will do nothing before having your directions, which, for the sake of the matter in hand, I should be glad to receive as early as possible. . .

The next letter announces a new aspect of the projected journey. In explanation, it should be said that finding Agassiz might be prevented by his poverty from going, the prince had invited him to be his guest for a summer in the United States.

AGASSIZ TO THE PRINCE OF CANINO.

NEUCHATEL, January 7, 1845.

. . .I have received an excellent piece of news from Humboldt, which I hasten to share with you. I venture to believe that it will please you also. . .I had written to Humboldt of our plans, and of your kind offer to take me with you to the United States, telling him at the same time how much I regretted that I should be unable to visit the regions which attracted me the most from a geological point of view, and asking him if it would be possible to interest the king in this journey and obtain means from his majesty for a longer stay on the other side of the Atlantic. I have just received a delightful and most unexpected reply. The king will grant me 15, 000 francs for this object, so that I shall, in any event, be able to make the journey. All the more do I desire to make it in your society, and I think by combining our forces we shall obtain more important results; but I am glad that I can do it without being a burden to you. Before answering Humboldt, I am anxious to know whether your plans are definitely decided upon for this summer, and whether this arrangement suits you. . .

The pleasant plan so long meditated was not to be fulfilled. The prince was obliged to defer the journey and never accomplished it. This was a great disappointment to Agassiz.

"Am I then to go without you," he writes; "is this irrevocable? If I were to defer my departure till September would it then be possible for you to leave Rome? It would be too delightful if we could make this journey together. I wish also, before starting, to review everything that has been done of late in paleontology, zoology, and comparative anatomy, that I may, in behalf of all these sciences, take advantage of the circumstances in which I shall be placed. . .Whatever befalls me, I feel that I shall never cease to consecrate my whole energy to the study of nature; its all powerful charm has taken such possession of me that I shall always sacrifice everything to it; even the things which men usually value most."

Agassiz had determined, before starting on his journey, to complete all his unfinished works, and to put in order his correspondence and collections, including the vast amount of specimens sent him for identification or for his own researches. The task of "setting his house in order" for a change which, perhaps, he dimly felt to be more momentous than it seemed, proved long and laborious. From all accounts, he performed prodigies of work, but the winter and spring passed, and the summer of 1845 found him still at his post.

Humboldt writes him not without anxiety lest his determination to complete all the tasks he had undertaken, including the Nomenclator, should involve him in endless delays and perplexities.

HUMBOLDT TO AGASSIZ.

BERLIN, September 16, 1845.

. . .Your Nomenclator frightens me with its double entries. The Milky Way must have crossed your path, for you seem to be dealing with nebulae which you are trying to resolve into stars. For pity's sake husband your strength. You treat this journey as if it were for life. As to finishing,—alas! my friend, one does not finish. Considering all that you have in your well-furnished brain beside your accumulated papers, half the contents of which you do not yourself know, your expression "aufraumen,"—to put in final order, is singularly inappropriate. There will always remain some burdensome residue,—last things not yet accounted for. I beg you, then, not to abuse your strength. Be content to finish only what seems to you nearest completion,—the most advanced of your work.

Your letter reached me, unaccompanied, however, by the books it announces. They are to come, no doubt, in some other way. Spite of the demands made upon me by the continuation of my "Cosmos," I shall find time to read and profit by your introduction to the Old Red. I am inclined to sing hymns of praise to the Hyperboreans who have helped you in this admirable work. What you say of the specific difference in vertical line and of the increased number of biological epochs is full of interest and wisdom. No wonder you rebel against the idea that the Baltic contains microscopic animals identical with those of the chalk! I foresee, however, a new battle of Waterloo between you and my friend Ehrenberg, who accompanied me lately, just after the Victoria festivals, to the volcanoes of the Eifel with Dechen. Not an inch of ground without infusoria in those regions! For Heaven's sake do not meddle with the infusoria before you have seen the Canada Lakes and completed your journey. Defer them till some more tranquil period of your life. . .I must close my letter with the hope that you will never doubt my warm affection. Assuredly I shall find no fault with any course of lectures you may give in the new world, nor do I see the least objection to giving them for money. You can thus propagate your favorite views and spread useful knowledge, while at the same time you will, by most honorable and praiseworthy means, provide additional funds for your traveling expenses. . .

The following correspondence with Professor Adam Sedgwick is of interest, as showing his attitude and that of Agassiz toward questions which have since acquired a still greater scientific importance.

PROFESSOR ADAM SEDGWICK TO LOUIS AGASSIZ.

TRINITY COLLEGE, CAMBRIDGE, April 10, 1845.

MY DEAR PROFESSOR,

The British Association is to meet here about the middle of June, and I trust that the occasion will again bring you to England and give me the great happiness of entertaining you in Trinity College. Indeed, I wish very much to see you; for many years have now elapsed since I last had that pleasure. May God long preserve your life, which has been spent in promoting the great ends of truth and knowledge! Your great work on fossil fishes is now before me, and I also possess the first number of your monograph upon the fishes of the Old Red Sandstone. I trust the new numbers will follow the first in rapid succession. I love now and then to find a resting-place; and your works always give me one. The opinions of Geoffroy St. Hilaire and his dark school seem to be gaining some ground in England. I detest them, because I think them untrue. They shut out all argument from DESIGN and all notion of a Creative Providence, and in so doing they appear to me to deprive physiology of its life and strength, and language of its beauty and meaning. I am as much offended in taste by the turgid mystical bombast of Geoffroy as I am disgusted by his cold and irrational materialism. When men of his school talk of the elective affinity of organic types, I hear a jargon I cannot comprehend, and I turn from it in disgust; and when they talk of spontaneous generation and transmutation of species, they seem to me to try nature by an hypothesis, and not to try their hypothesis by nature. Where are their facts on which to form an inductive truth? I deny their starting condition. "Oh! but" they reply, "we have progressive development in geology." Now, I allow (as all geologists must do) a KIND OF PROGRESSIVE DEVELOPMENT. For example, the first fish are below the reptiles; and the first reptiles older than man. I say, we have successive forms of animal life adapted to successive conditions (so far, proving design), and not derived in natural succession in the ordinary way of generation. But if no single fact in actual nature allows us to suppose that the new species and orders were produced successively in the natural way, how did they begin? I reply, by a way out of and above common known, material nature, and this way I call CREATION. Generation and creation are two distinct ideas, and must be described by two distinct words, unless we wish to introduce utter confusion of thought and language. In this view I think you agree with me; for I spoke to you on the subject when we met (alas, TEN years since!) at Dublin. Would you have the great kindness to give me your most valuable opinion on one or two points?