which it is hard to assign precisely the date in the series of geological events. On the one hand we have Buch, Hoffman, and Ball, fully persuaded that the same causes which elevated the Swiss mountains produced the depressions which separate them. They think that the elevation was accompanied by crevasses more or less profound, which have formed the valleys, and that in the interior there exist other cavities, the roofs of which will be subsequently broken in-the present lakes being the remains of such cavities or founderings which have not yet been filled up by the silt brought down by the rivers. On the other hand, the disciples of Buffon, Playfair, and the Werner school, attribute the valleys and water-basins to erosion, or the destructive action of fluids in motion. The latter class, as we have already noticed, are split into two parties, and disagree as to the nature of the erosive medium-the one following their ancient masters, look to the currents of the sea, rivers, and torrents; the others, amongst whom are some of our own, and French and continental geologists, advocate the newer theory of their having been scooped out by the grinding action of massive glaciers. Each of these theories may be justified by particular facts; and M. Desor, at least, adopts them both, and applies either one or the other, as circumstances demand, distinguishing the lakes as orographic, and lakes of erosion. The former may be further divided into three classes-the lakes in synclinal valleys, such as the lake of Bourget; those in isoclinal, such as Brienz and Wallenstadt, and those in the transverse valleys or cluses, of which the lakes of Thoune and of Uri are examples. The lakes of the Alps, according to M. Desor, are chiefly orographic; whilst those of Neuchâtel, Bienne, Morat, Zurich, Constance, and others in Lower Switzerland, are lakes of erosion. The question of the epoch of their formation is, however, very much complicated when the strata around them are examined. All over Lower Switzerland and the Jura are spread the well-known "Alpine blocks," which by their mode of transport would necessarily have passed above the lakes in arriving at their actual sites from their original beds; and we cannot conceive why, if a current brought them, it should not have filled their basins and made a great mound of débris at the débouchures of the Alpine valleys. This difficulty involving the impossibility of the suspension of such blocks in mid-air, or the unlikelihood of their sustention on the surface of water 1,000 feet above the valley below, has been one of the main causes of the readiness with which the hypothesis of the former greater extension of the glaciers has been received, for across the surfaces of the icefilled depressions the Alpine blocks would have naturally travelled from the Alps to the Jura. This general body of ice, covering all the valleys and deep hollows, is certainly a cause of uncertainty as to the epoch of the formation of the lakes, for they may evidently be anterior to the glacial epoch, their basins during that era being filled with water or ice; or they may be posterior, although M. Studer is not disposed to admit a posterior origin, which appears too recent to reconcile with the evident connection of the basins and valleys with the orography of the country.

Another difficulty occurs. For a long time there has been known

to exist below the boulder-drift a terrain erratique, a deposit of sand and clay horizontally stratified, and possessing all the characters of a river deposit -the terrain du transport of Elie de Beaumont, or the alluvion ancienne of Necker, the diluvium of recent authors-in the gravels of which the constituent rocks of the pebbles are found to be derived from the Alps or the sub-Alpine hills, whilst the boulderblocks themselves also present different characters, according to the nature of the different valleys through which they have been carried, and corresponding to the rocks in situ in such valleys and their tributaries. It is evident, as M. Studer remarks, that the presence of this ancient alluvium throws us again into all those difficulties from which we thought ourselves freed by the hypothesis of the former greater extent of the glaciers. The difficulty, he thinks, may perhaps be diminished by reducing as much as possible the mass of those gravels, the transport of which across the lakes, before the great extension of the glaciers took place, seems incontestable; and that, as these horizontal beds of ancient alluvium repose upon the denuded or sliced-off edges of the inclined beds of molasse, the date of their formation is necessarily placed between the catastrophe which elevated the Tertiary beds and the epoch of the great extension of the glaciers. After a careful analytical survey of the physical and geological aspects of the lake-country, M. Studer comes to the conclusion of the insufficiency of erosion in accounting for the origin of the valleys and lakes of the Alps; and he considers there is no alternative but to recognize with M. Escher an intimate connection between a great number of the Alpine valleys and the inclined positions of the beds of the mountains which separate them. These, then, are true orographic valleys, such as M. Desor has noticed in the Jura, and to the two kinds he has described, the synclinal and isoclinal, there ought to be added for the Alps another-the anticlinal valleys. The cluses, he further considers, are evidently fractures enlarged by erosion; and he adds a fourth class of valleys - those of subsidence. If lava-currents, which often traverse loose sand, do not burrow into the soil in their progress, is his argument, how can glaciers which have less power than even such currents of water as our senses will not detect the motion of, and which even at this slow rate move over an under-plane of water and ground-adherent ice, effect such enormous erosion as is involved in these lake-basins? looks, therefore, to subsidences as their chief cause. In this case the ancient alluvium at the bottom of the basins involves the supposition of the lapse of a considerable period of time between the disturbance and the filling up of the depths of the crevasse; and as a proof of the occurrence of such an interval, he refers to the great difference between the faunas and floras of the last or newest beds of the molasse, and the first or oldest of those of the alluvium, urging how great a length of time it would require to produce such differences of climatal conditions as to enable a fauna such as that of the Confederate States to supplant the present fauna of Europe-a difference which is not greater, however, than that between the animals of the Molasse age and the elephants, oxen, and deer of the Diluvium.

He

V. MINING, MINERALOGY, AND METALLURGY.

THE most noteworthy fact in connection with British mining which has presented itself during the quarter, has been the production of gold from the quartz lodes of the Cambrian Hills. Many years have passed away since we were told that gold was to be found in Merionethshire. Some of the precious metal was exhibited in 1851, but this had been obtained at a cost which far exceeded its value. In 1861 the Vigra and Clogau mine gave 2,784 standard ounces of gold to the adventurers, but in 1862 they obtained 5,299 ounces. For some time the prospects were dull; large quantities of quartz were worked containing no visible gold, and an infinitesimally small proportion was separated by amalgamation. However, the prospects brightened towards the close of the year 1863; and during the past quarter the following quantities have been duly reported:

This is perhaps the most extraordinary yield on record of gold from a quartz vein. We find, however, by the report of the Vigra and Clogau Mining Company, that since the date of their last report, 1,059 ounces of gold have been received, this being obtained from quartz giving 24 ounces of gold to the ton on the average.

In the neighbourhood of Bala Lake some discoveries were made last year, from which much was expected. This has not, however, been realized. But in January some quartz was operated on from Castell-carn-Dochan, giving from 5 ounces to 7 ounces to the ton. At Penrhos and Tynyrhenrhos, stones have been taken from quartz lodes containing visible gold. The extraordinary products of the Vigra and Clogau mine naturally awaken the hopes of the adventurers in the other gold-mines around Dolgelly. It should, however, be borne in mind by all, that nothing can be more capricious than the occurrence of gold in the quartz lodes. We know not when the gold may disappear-we have no rule to guide us as to its discovery. Therefore, caution should be the rule of all speculators, who are tempted by the auriferous treasures of the Welsh mountains.

British mining presents but little that is worthy of our record. The fact that upwards of 10 tons of nickel and cobalt speiss has been obtained from the sandstone of Alderly Edge, in Cheshire, is of interest.

In our last number we drew especial attention to the coal-cutting machines of the Ardsley Coal Company, and of Ridley and Jones. Mr. Firth, of the former company, informs us that the Ardsley machine has been reduced to two feet in length, "therefore," he says, "in the progress of invention we have gone far beyond the one in question." The

Ardsley machine is being used in several collieries, and the reports are in the highest degree satisfactory.

In connection with this really important subject, a very admirable paper was read at the Institution of Civil Engineers, on February 16, by Mr. Thomas Sopwith, jun., on "The Actual State of the Works on the Mount Cenis Tunnel, and Description of the Machinery Employed."

So much has been said of late respecting this extraordinary undertaking, and of the machinery employed in boring this tunnel, that we need not occupy our pages with any description of either the one or the other. The following brief quotation shows the present rate of progress: "The tunnel, on 30th June, 1863, had been driven (including the advanced gallery), at Modane, 1092-25 metres, and at Bardonneche, 145000 metres. The advancement in June last, at Modane, was at the rate of 4.719 feet per day. At this rate of progress at both ends, the tunnel would be finished in nine years two and a-half months from that time."

*

The machine employed by M. Sommeiller is very accurately described, and admirably-executed drawings are given in a work by M. Armengaud (aîné). In the same work will be found a description of a rotating perforator, " perforateur rotatif," of Schwartzkopf and Phillipson. This machine is exceedingly portable, and especially applicable to the conditions which prevail in our metalliferous mines.

Attention has been directed, since the experiments which have been made at Mont Cenis, to the use of boring machinery in the metalliferous mines of this country. A machine, invented by Mr. Crease, but resembling strongly the machine just noticed, has been used in the Vigra and Clogau gold mine, near Dolgelly. The result of the trials. made in driving a level, went to show that several improvements were required; consequently it was placed in the hands of Mr. Green, of Aberystwyth, and that gentleman has shown much mechanical ingenuity in adapting new principles to the original idea. The improved, or Green's boring machine, is shown in the accompanying plate. This machine consists of (Figs. 1, 2) an upright pillar of cast-iron, 3, fixed upon a low tram waggon, 1, running upon rails in the level, and having within it, in the upper part, an upright screw, 4, and cross-head; and in the lower part another screw, 2, by means of which the machine can be firmly fixed between the floor and the roof. This pillar is encircled by an iron collar, 5, which can revolve round the pillar, but which can, by means of a rack and pinion, 7, 8, worked by the worm, 6, be raised or lowered upon it. Attached to this collar is an arm with adjustments, 9, 10, 11, 14, which carries the boring machine proper (Fig. 4). At the end of the arm is a cylinder resting upon a screw bed (Fig. 3), 15, in which works an ordinary slide valve. The piston is shown in section in Fig. 4; to it is attached a hollow pistonrod, in which the borer is placed. By the side of the cylinder are

* Publication Industrielle des Machines, Outils et Appareils les plus perfectionnés et les plus récents, employés dans les différentes branches de l'industrie française et étrangère.' Par Armengaud (aîné). Paris: MM. A. Morel et Cie. See also Les Mondes, Revue Hebdomadaire des Sciences,' 21 Jan., 1864.