namely, its great price, while, at the same time, it is by no means such as to approach in any striking degree to the perfection which might be desired. Much, therefore, is it to be wished that Mr Audubon should undertake the delineation of the birds of Great Britain, which, with his matchless talents, aided by those of Mr Havell, would eclipse, not only all other representations of these birds, but even the "Birds of America," unrivalled as that work now is. Sure, the "Imperial Isle," the "Empress of the nations," ought to possess a work of this kind suited to her rank in the political and moral systems of our beautiful and mysterious world.

ORNITHOPHILUS.

'Observations on the Glaciers of the Alps. By F. J. HUGI, Professor at Soleure.

A JOURNEY devoted exclusively to geography or meteorology, executed by a man well versed in physical and natural science, affords a rich store of important observations, which aids powerfully in unveiling the secrets of nature. The narratives of De Saussure and Humboldt prove what advantage a superior mind may obtain from inspecting these particular regions. The Alps, although situated in the centre of the most civilized continent, have remained a long time without being studied; it is well known what science owes to the particular attention with which these mountains were studied by one of these learned men whom we have mentioned. Other naturalists have trodden in his footsteps, and notwithstanding, there are yet many points on which new observations are useful and often necessary.

Situated in a temperate climate, the Alps, by their elevation above the level of the sea, afford a multitude of phenomena which belong to polar regions, and which, notwithstanding, exhibit the peculiar characters which their elevation impresses. Mr Hugi, already known by many valuable works relating to physics and natural history, having, in 1828 and 1829, made excursions among the Bernese Alps, has collected the observations

* Translated by the Rev. William Ettershank, M. A.

which he had made on that interesting country, in a memoir which at first had been read to the Society of Natural History of Soleure, of which Mr Hugi is President, and which had afterwards been printed. The excursions of the author have been principally in the eastern part of the chain which separates the Canton of Berne from the Vallais, and farther from the Grisons. They reach to the summit of the Finsteraarhorn, the most elevated peak of the chain, and which does not yield to any among the Alps except Mont Blanc and Mont Rosa. The narrative of this attempt and some others analogous, will furnish matter for an interesting article in another number of this Journal; but we shall confine ourselves for the present to record some observations on the glaciers. The subject has been treated by Saussure in the first volume * of his Travels among the Alps, with the perspicuity and correctness which always distinguish this celebrated geologist; but new documents will not be useless. The attention of De Saussure, at the period when he published this part of his work, had been particularly directed to the chain of Mont Blanc, and consequently to the Glaciers of Savoy. The observations of Mr. Hugi have been made concerning a different region, perhaps still richer in glaciers. It is interesting to compare the latter with the former.

The author established at first, as had been done by De Saussure, a distinction between two kinds of glaciers, for which the German language possesses two different expressions (firn and gletscher), and which, in French, are confounded under the denomination of glacierst. The former is that stratum of granular and permanent snow, which covers the summits and the declivities of very high mountains; the latter is that of those large rivers of ice, more or less opaque, which descend from those mountains by lateral valleys, and often over an extent of many leagues, even to the heart of the inhabited valleys; they are also sometimes named mers de glace. Among the latter, the most remarkable are those which surround Mont Blanc, Mont Cervin, and Finsteraarhorn. All the others, from Savoy

• Edition in 4 vols. quarto, Neuchatel.

+ Having had frequent opportunities of examining the glaciers of the Bernese Alps, we can vouch for the accuracy of Prof. Hugi's statements. -Trans.

to the Tyrol, are of less extent; the greater number belong rather to the first kind, that is to say, present frozen summits; which a little lower become true glaciers of the second kind.

Mr Hugi has particularly studied the vast sea of ice.comprised between Grendelwold, the Vallais, Hasli, and the valley of Lotch, a desert region, above which there arise five or six colosses, of which the elevation exceeds 12,000 feet, and from whence issue, in all directions, a great number of glaciers. The whole of the glaciers, of the different kinds of groups on this region, afford an extent that may be estimated at 44 leagues from south to north, and at 81 from east to west, which gives a surface of about 38 square leagues.

"In general," says the author, "they assign too great a thickness to the mass of glaciers. It is between 30 and 80 feet at its extremity. Having met in the inferior glacier of the Aar, about a league above its extremity, a crevice which reached to the soil, I sounded it, and found a depth of 120 feet. There is on the great glacier of Aletch, at two leagues above its extremity, a little lake (Moriler See), often empty, of which the border affords a vertical cut of the glacier, which is not more than 100 feet; two leagues still higher, the glacier rises on the rocks between the peak of Aletch and the Faulhorn, and at this place it cannot be estimated at more than 150 feet. A deep crevice in the glacier of Viesch behind the Finsteraarhorn, does not indicate a greater thickness of ice. Often the glaciers of both kinds glide over the rock, and break vertically, and their anterior part is precipitated into an abyss; in these cases, the cut formed never exceeds 100 feet. During 20 years the inferior glacier of the Aar has advanced about one-fourth of a league. The shepherds who frequent its environs, and who know the depth of the valley which it has filled, affirm that the glacier cannot be more in this place than 80 feet thick.

"On the high peaks the frozen mass diminishes even to the thickness of only some feet. The peak of the Finsteraarhorn was completely bare in 1829; even its bases were seen in some places. The covering is equally thin on the Schreckhorn, the Jungfrau, the Titlis, and the greater part of the summits of the Alps."

“If, moreover, we consider the connexion that exists between

the mountains and the glaciers which cover them; if, in particular, we consider the disappearance under the ice of certain formations or strata of rocks, and their reappearance in other places; if we attend to the course of the acclivity of the valleys from the extremity of a glacier to its commencement, &c.; we obtain the following conclusions:-The mean thickness of the glaciers of the second kind, which descend into the inferior valleys, is from 80 to 100 feet:* the thickness of those glaciers which are more elevated, and which fill the deeper valleys, may be considered as ranging from 100 to 180 feet. The glaciers of the first kind, which cover the summits, or extend over the declivities, scarcely attain 40 feet in thickness. Doubtless, there are deep holes in the rocks, where the thickness of the ice is much more considerable; the thickness likewise diminishes at the limits of its extent. Besides, it is often formed after avalanches in extraordinary heaps in certain places. In like manner, a winter very abundant in snow may augment, for a short time, the thickness of the covering of the peaks."

"The ice of a glacier of the second kind, is almost as hard as rocks; the sun, the rain, and the warm winds, slightly melt its surface, but never soften the mass. If we travel on one of these glaciers, even to more elevated regions, we see it, at a height of about 7600 feet above the level of the sea, pass rapidly into the condition of ice of the first kind. It is composed of round grains, about the size of a pea; the sun softens it to such a degree, that we often sink in it to the knees; but a moderate cold restores it to its former hardness. The line of separation of the glaciers of the two kinds, is no other than the limit of perpetual snow, that is to say, the height above which snow does not melt in summer. It is customary to place this limit in our mountains between 6000 and 9000 feet; but if we consider more accurately the melting of the snow, we shall be obliged to assign to this limit a much greater range. It does not appear that they have sufficiently distinguished, in this determination, each of the two kinds of glaciers, and the snow properly so called; they have not observed correctly the different manner

• De Saussure obtained precisely the same result at the glacier of Bois, but he thinks that accidentally he met with much thicker ice. Vol. i p. 440 and 523.

in which these different masses are associated; they have been contented with viewing them from the bottom of the valleys. The inferior limit of glaciers of the second kind descends even to 3200 feet above the level of the sea, and varies according to the situation of the glacier, its declivity, the rocks which surround it, the depth, and the steepness of the ravine which encloses it, to a height of 7400 feet, that is to say, to the lower limit of glaciers of the first kind. The limit of the snow, specially considered as to its melting, is still much more uncertain. While, on the southern declivities, it rises even to 10,000 feet; it descends on the northern extremities even to the lower limit of glaciers of the second kind; it varies considerably in the same place, according to seasons, the insulated nature of the peaks, the connection of the declivities, their respective position and inclination, the nature and stratification of the rocks, the accumulations of debris, the interior heat of the earth, the vegetation, and, above all, the prevailing direction, the force, and the temperature of the winds; all these cirumstances exert such an influence upon the height of this line, that it is impossible to determine it precisely. There, where avalanches and violent tempests have not formed extraordinary accumulations, it may happen in the month of August, that, at a height of 12,000 feet, there is not a trace of snow to be found."

Concerning the lower limit of the glaciers of the first kind, the alpine excursions made by Mr Hugi during many years have shown that it not only does not vary in the same place, but that it varies little from one place to another, and that it is but little affected by the situation of the declivities and other circumstances which have been mentioned. Observations made in different parts of the Bernese chain, show that it is towards *7600 feet of elevation, where the permanent glaciers of the first kind commence, and that at 7700, we find ourselves wholly in the region of these glaciers. Among the Pennine Alps, this limit appears to be a little more elevated, as we find it at 7800 feet on the Gries, and the ridge of the valley of Binnen, mountains situated at the eastern extremity of the chain of the Vallais.

The intimate constitution of the ice, in the glaciers of the two kinds, offers materials for numerous observations. The fol