solely on public notoriety, it was demanded that their movement should be shown by direct observations, before any conclusions were drawn from it. A problem before purely geological, was thus suddenly changed into a question of fact, requiring a long series of researches and experiments.

Though already overburdened by his various labors, Agassiz did not shrink from this task. He saw at once, that to obtain a satisfactory solution it was not enough to have such isolated observations as can be made in a short visit. It was necessary to examine the glaciers not only at their termination, but also throughout their whole extent; to ascertain the influence of inequalities of the soil on their movements; the temperature of the ice and the effect of external agencies upon it, under all circumstances. In a word, it was necessary to do what had never been done before; namely, to establish an intimate acquaintance with the glaciers.

Mr. Agassiz, after having visited in succession most of the glaciers, fixed his head-quarters at the Glacier of the Aar, whither he went for eight years consecutively, with his friends, to pass his summer vacations, at first with no shelter except a large boulder lying on the middle of the glacier, and which soon became famous under the name of the Hôtel des Neuchâtelois. Afterwards he built a little stone cabin on the left margin of the glacier;-this received the name of "the Pavilion." Here he prosecuted the long series of researches that have obtained so much celebrity in the scientific world.

Although his retreat was situated eight thousand feet above the level of the sea, and twelve miles from any habitation, it was soon well known throughout the country, and there might often be seen assembled a select company, in which all nations were worthily represented.

The scientific results obtained from these investigations are contained in two works. The first, published in 1840, under the title of "Etudes sur les Glaciers," comprises a description, with plates, of the principal phenomena connected with the glaciers, together with a detailed account of the author's views as to their former extent. The second, recently published, under the name of "Système glaciaire," is the last, and seems to us likely to be one of the most successful works of the author; it contains a detailed account of the investigations made during his last five visits, (from 1841 to 1845,) with the view to determine the mode of progression of the glaciers in all parts of their course, at all seasons of the year, and under all conditions of temperature. This work is accompanied by beau

tiful plates, and a topographical chart of the Glacier of the Aar, on a very large scale, (1) allowing even the minutest details of the surface to be given, so that this glacier is better known, in a topographical point of view, than any canton or

state.

We cannot, of course, undertake an analysis of the results. obtained from all these observations, and summed up at the end of each chapter. We will only say, that this work, if we mistake not, is to be considered as a sort of introduction to a more extensive undertaking, for which the author has already collected a great number of materials, and which is to comprise the history of the last great revolutions which the earth's surface has undergone. We understand that Mr. Agassiz finds in this country a vast field for research, and valuable materials in the works of American geologists.

Referring those of our readers who are desirous of particular information on this matter, to the above work, we conclude our sketch with a single passage of a different character, from a little volume by Mr. Desor, entitled "Excursions et séjours de M. Agassiz et de ses compagnons de voyage, dans les Glaciers et les hautes régions des Alpes,"*-containing a lively and readable account of the incidents and adventures of their mountain-life, as well as of the topography and scenery of the country, and from which, (did our limits allow,) we would gladly make larger extracts. It is easy to conceive, that, living in the midst of the magnificent peaks by which the Glacier of the Aar is surrounded, the temptation to scale their dizzy heights must be strong, especially when fortified by a scientific interest. Mr. Desor gives accounts of various ascents undertaken by their little company; the most memorable of which is that of the Jungfrau, which took place in 1841; having for its object the study of the structure of the snow and ice on the higher summits. The Jungfrau is the most admired of the Swiss mountains, and-next to the Finsteraarhorn, Mont Blanc, and the Monte Rosa-the highest of the Alps, being 13,720 feet in elevation. We extract from the abovementioned work some particulars of this ascent, which was much talked of among the mountaineers; since, by many of them, the Jungfrau was considered inaccessible. Starting from the hamlet of Méril, on the Viesch Glacier, at

Neufchatel and Paris. 1844. 18mo. For many interesting details, among others the account of a descent into one of the crevices of the glacier, to examine its structure, see an article by Mr. Agassiz himself, in the Edinb. New Phil. Journal, for 1842.

p. m.

five o'clock, a. m., Mr. Agassiz and his companions arrived, at two, p. m., at the base of the highest summit, the inclination of which, on being measured, was found to be forty-five degrees. This declivity, moreover, was covered with hard, slippery ice, in which it was necessary to cut steps; and this, together with the intense cold, so retarded their progress, that, at one time, they advanced only fifteen steps in a quarter of an hour. The summit formed the vertical section of a cone; and the ice being less hard at the edge of the precipice, they walked, by the advice of their guide, on the very brink of the abyss. "Several times," says Mr. Desor, "on thrusting out my staff rather further than usual, I felt it pass through the roof of snow,"-which, as is usually the case, projected like a cornice from the edge of the precipice, "and then we could look, (whenever the fog separated for a moment,) perpendicularly through the hole into the vast gulf below." The fog, which had hidden every thing from sight, cleared away when they reached the summit, at about four, "Here, for the first time, we had a view of the valley of Switzerland; we were on the western edge of the section of the cone, having at our feet the barrier that separates the valley of Lauterbrunnen from that of Grindelwald. The mountain here forms an abrupt angle, a dozen feet below the summit, and we saw, with a sort of affright, that the space which separated us from the highest point was a sharp ridge, about twenty feet long, the sides of which had an inclination of from sixty to seventy degrees. There is no way of getting there,' said Agassiz, and we all inclined to the same opinion. Jacob, [their principal guide,] on the contrary, said there was no difficulty whatever, and that we should all get over. Laying aside what he carried, he commenced the undertaking by passing his staff over the ridge, so as to bring it under his right arm, and thus climbed along the western slope, burying his feet as much as possible in the snow, in order to obtain foothold." In this way he passed over, and after having removed the snow from the summit, persuaded them all to follow. "The summit is a very narrow triangular space, about two feet long, and a foot and a half wide, with the base towards the valley of Switzerland. As there was room only for one person, we took turns. Agassiz mounted first, resting on Jacob's arm. He remained about five minutes, and when he rejoined us, I saw he was unable to suppress the vivid emotion caused by the overwhelming grandeur of the spectacle."

6

"It is not the vast prospect that makes the charm of the higher mountains. We had already found from former experience, that distant views are generally indistinct. Here, on the summit of the Jungfrau, the contours of the distant mountains were still less defined. But what fascinated us was the

spectacle in our immediate neighbourhood. Before us was spread out the valley of Switzerland, and at our feet were piled up the lower chains, the apparent uniformity of whose height gave still greater sublimity to the vast peaks that towered up almost to our level. At the same time, the valleys of the Oberland, which, until now, had been covered by light vapor, were uncovered in several places, revealing to us through the fissures the world below.' We distinguished on the right the valley of Grindelwald; on the left, far below, an immense chasm, at the bottom of which a brilliant thread wound along, following its windings. This was the valley of Lauterbrunnen, with the river Lutschinen. . . . On the south the view was interrupted by clouds, which had for some hours been gathering on the Monte Rosa. We were recompensed for this, however, by a very extraordinary phenomenon, which took place under our eyes and interested us much. A thick mist had gathered on our left, towards the southwest; it ascended constantly from the Rott-thal, and began to extend to the northward. We already feared lest it should surround us a second time, when we found that it terminated abruptly at the distance of a few feet from us. Owing to this circumstance, we beheld before us a vertical wall of mist, the height of which we estimated to be at least from 12,000 to 15,000 feet, since it rose from the valley of Lauterbrunnen to a considerable distance above our heads. As its temperature was below the freezing point, the little particles of vapor were transformed into crystals of ice, and reflected the sun's rays in all the colors of the rainbow; we seemed to be surrounded by a mist of gold."

The scientific results of this ascension were the discovery that the snow, even on the highest summits, is not changed into ice, though it rests on a crust of very compact ice; also, that the summit of the Jungfrau is gneiss, and not limestone, as had been supposed. Among the lichens gathered by Mr. Agassiz at the summit, was a new species (Umbilicaria Virginis, Schor.); the others were among those found by Saussure on

Mont Blanc.

The general features of Mr. Agassiz' history since 1845

are probably known to most of our readers. In the fall of 1846, being charged with a scientific exploration by the king of Prussia, and having also received an invitation to lecture before the Lowell Institute, he arrived in this country, where he has since resided. On the establishment of the Lawrence Scientific School, at Cambridge, the professorship of Zoology and Geology was offered to him, and after some deliberation accepted. Of the results of his labors in this country it is yet too soon to speak; but the impulse given to these studies by his presence is a matter of public notoriety, and of the highest importance to scientific culture among us.

In conclusion we give a chronological list of the most important of Mr. Agassiz' works.

Spix et Agassiz, selecta genera et species Piscium, quos in itinere per Brasiliam annis MDCCCXVII-XX peracto collegit et pingendos curavit. 2 vol. cum 55 Tab. lithogr. et 46 Tab. col. Munich. 1829-31.- Recherches sur les Poissons fossiles. Soleure. 1833-43. 5 vols., 4to, et 5 vols. Planches, fol.-W. Buckland, Geologie u. Mineralogie in Beziehung z. natürl. Theologie. Aus d. Engl. übers mit Anm. u. Zusätz v. L. Agassiz. Neufchatel. 1838. Mit 69 Tafeln. 2 Bde. 8vo. Description des Echinodermes fossiles de la Suisse. Soleure. 1839-40. Avec 25 Pl. 4to.-Monographies d'Echinodermes vivans et fossiles. Soleure. 1838-40. 4 vols. 4to.Etudes critiques sur les Mollusques fossiles. 1840-45. 4to.- Histoire naturelle des poissons d'eau douce de l'Europe centrale. Soleure. 1839-40. Fol.-Mémoire sur les moules de Mollusques vivans et fossiles. Soleure. 1840-42. 4to.-Etudes sur les glaciers. Soleure. 1840. 8vo. 8 vols. Avec 32 Pl. fol. [Also the same work in a German translation.] - Nomenclator Zoologicus, seu nomina generica generum animalium tam viventium quam fossilium. Soleure. 1842-1846. 4to.-Monographies des Poissons fossiles du système Dévonien. 1844-45. 4 vols. fol. Avec un Atlas.-Iconographie des coquilles tertiaires. Dans les Mém. de la Soc. Helv. des Sc. Nat. Vol. 7. 1845.- Bibliographia hist. naturalis. [In publication by the Ray Society.]Système glaciaire, ou recherches sur les glaciaires et leur mécanisme. Avec un Atlas. Paris. 1847.- Catalogue raisonné des Echinides vivans et fossiles, par MM. Agassiz et Desor. [Annal. des Sc. Naturelles, 1847.]

Mr. Agassiz has also prepared (by request) an elementary work on Natural History, which is now in course of publication.