that the collective names of the rocks in the tabular sections are correct, both on grounds of principle and of geographical propriety. The tabular section of Wales here given differs not at all from a general section exhibited by him in 1833.

On the Physical and Chemical Constitution of Natural Waters. By M. E. MARCHAND.

From the researches which I have now for a long period made upon the physical and chemical constitution of natural waters, and their geological origin, the following conclusions may be drawn:

1st, All natural waters, at least in the circumstances of which I shall presently speak, contain iodine and bromine. 2d, All these waters contain lithia.

3d, The whole of them, when they take their origin from superficial deposits connected with chalk, or in calcareous districts, contain iron.

4th, The origin of iodine and of bromine in water proceeds from the transportation of these principles from the water of the sea, from the vapours or the aqueous particles which incessantly escape from it, and which, transported to the continents, fall to the earth, in the state of rain, of snow, or of hail. The waters composing rain and snow generally contain an appreciable proportion of iodurets and of bromurets.

5th, In well-wooded countries, iodine and bromine may disappear from the water which holds them in solution, by passing to a saline state under the influence of vital forces, due to the number of mineral principles engendered by vegetation. The ashes of the greater part of our forest trees, elm, beech, fir, &c., contain iodine.

6th, The determinating causes of goitre and cretinism are not to be found in the existence of carbonate of magnesia in the waters which those afflicted with goitre and cretinism use for their necessary food.

7th, The determinating cause of these maladies exists rather in the absence of iodine and bromine from the number of constitutive principles of these waters.

8th, The physical and chemical constitution of water varies each day in the year, and, perhaps, even in every moment of the day. At the seasons when the temperature is highest, the

density of the water is also strongest, and their richness in saline principles most considerable. A sudden variation in temperature produces also a considerable variation in the constitution of the water.

9th, We knew before this time the influence of the clearing of forests upon the abundance or the scarcity of springs. We had never, however, reckoned upon the influence of vege tation in general, and, particularly, of the influence of the cultivation of agricultural plants upon these same phenomena. It is generally believed that springs are more abundant in winter than in summer. This opinion is erroneous; it results, from my observations, that, in limestone formations at least, the springs are more abundant when vegetation is most active, and that they decrease in importance in proportion as vegetable life is extinguished. They are at their minimum of production about the 15th or 20th of January.

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10th, All our water, of springs, of brooks, and of rivers, contain azotes; and, nevertheless, the water of the sea which receives these different fluids does not contain appreciable traces of these salts. This may be accounted for, on the one hand, from the influence of the respiration of fishes; the azotes contained in water, in passing with it through their gills, undergoes a decomposition of which the result is ammoniacal. On the other hand, in the depths of the ocean, a considerable quantity of univalve and bivalve mollusca are found (oysters, mussels, &c.), which continually excrete a certain quantity of free sulphuretted hydrogen, which, in its nascent state, ought still to convert to the ammoniacal state the nitric acid of the azotes with which it is in contact. The mud and slime deposited by the waters contain crystals of ammonico-magnesian phosphates, and the waters contain hydrosulphuric acid. ne odt og on. 19 dog w koszolira 11th, Hydrosulphuric acid, free or combined, is also often, if not always, found in rain water, It is this principle which supplies with sulphur the plants belonging to the cruciferous family.

12th, From this last fact, it results that those localities which are infected by hydrosulphuric acid, may be purified therefrom by the cultivation of plants belonging to this family.

Sketch of the Climate and Vegetation of the Himalaya. By THOMAS THOMSON, M.D., Assistant Surgeon in the H.E.I.C. Service, Bengal Establishment.*

The great range of the Himalaya, when taken in conjunction with the still more elevated mountains behind, which are in nowise distinguishable from it, constitutes the most stupendous mass of mountains in the world, not only from containing the highest peaks, but also, and still more remarkably, as presenting by far the greatest area of elevated land.

This gigantic mountain mass lies to the north of the great plain of India, from which it rises on the whole very abruptly. It has a direction very nearly from east to west, its west extremity is, however, a little more northerly than the east, the latitude rising from 26° at the east, to 33 at the west extremity.

The mountain-chain to which the name of Himalaya is most properly applied, may be considered as bounded at the south by the plains of India, and on the north by the rivers Indus and Burrampooter, which have their sources in the same spot, and run one to the east, the other to the west, among lofty mountains, till they enter the Indian flat country. Nearly in the centre of this chain, in the most westerly part of Nepal Proper, lies the point of separation between the two great river systems, that of the Indus, and that of the Burrampooter, constituting a north and south axis, which, when better known, will probably prove to be the grand axis of Asia. [...

From this centre the chain of the Himalaya extends to nearly an equal distance in both directions, the central axis of the chain being the line of water-shed between the streams which run toward the plains of India on the south, and those which flow toward the Burrampooter and Indus on the north. This line of water-shed or central axis, will, on inspection of a map, be seen to be in general somewhat to the north of half-way between the two boundary lines of the chain, so that the distance from the axis to the plains of India, is greater than from the same place to the northern rivers. The mean width of the whole chain may be stated roughly to average about 150 miles, of which 90 are to the south of the line of water-shed, and 60 to the north of it.

From the central axis of the chain, lateral ranges of mountains run both to the north and south, stretching in the latter direction as far as the plains of India, and separated from one another by deep narrow valleys, which extend far into the interior of the mass of mountains. out bed? 10 ti

*icht * Vide Proceedings of the Philosophical Society of Glasgow, 1851,

The number of lateral chains of the first class which form the line of division or water-shed between the basins of the great rivers on the south side of the central axis of the Himalaya, is about fourteen, separating from one another in a series from left to right the waters of the Jhelum, the Chenab, the Beas, the Ravi, the Sutlej, the Jumna, the Ganges, the Gogra, the Gandak, the Kosi, the Teesta, and the Subhansheri. These great chains, like the central axis, throw off lateral branches, which separate from one another the different branches, by the union of which within the mountains the great rivers are formed.

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The elevation of the central axis of the Himalaya is probably at a mean about 18,000 or 20,000 feet; it is nearly uniform at about these elevations throughout a great part of the chain, but gradually diminishes toward both ends. Like all mountain-chains, it presents alternations of high and low portions, the lower parts, or passes, as they are called, from their affording the means of passage to travellers from one side or the other, being at the upper extremities of the river basins. These passes are, with a few exceptions, rarely under 17,000 or 18,000 feet. The lateral chains, starting from the more elevated portions of the central axis between the passes, gradually diminish in elevation as they approach the plains of India, not, however, with any exact uniformity of progression, for it is not unfrequent to find them rise into lofty peaks considerably more elevated than any known part of the central axis. The greater part of the giant peaks, which rise to an elevation of 26,000 or 28,000 feet, are situated in this manner, not on the central axis, but to the south of it; it is, however, by no means improbable that masses of equal elevation, not yet measured or observed, may occur behind them, it being unquestionable that the general elevation of the country continues to increase as we advance to the north, and that we have not yet (except in one place) attained to any point from which a descent is commenced towards the northern plains.

The direction of the principal lateral chains and of their included' valleys, is, on the whole, perpendicular to the main axis, but with an inclination from the centre; those on the extreme east inclining to the eastward, while those on the extreme west have a very westerly direction. There are certain anomalies in the courses of the rivers, particularly at the north-west extremity of the chain; which, how-ever, may be overlooked in a view so general and cursory of these rivers, as must necessarily be taken on the present occasion. The most marked of these peculiarities may be observed in the course of the Sutlej, which runs for a very considerable part of its course nearly parallel to the Indus before it turns toward the plains, thus separating the western part of the Himalayan chain, almost from its very origin, into two branches, one of which separates the Sutlej from the Indus; the other to the south of, and nearly parallel to,

the other, divides the basin of the Sutlej from that of the Jumna and Ganges.

From the great depth of the valleys which separate the different mountain-chains, it but seldom happens that any road crosses from one valley to another; a traveller has therefore, in general, excellent opportunities of studying the direction and ramifications of the different chains, either in following the course of the valleys, or by travelling along the top of the ridges. In both cases he will find that his course is an undulating one, each chain and each branch of a chain being a curve, which bends first to one side and afterwards to the other, giving off generally a spur on the convex side, while the head of a valley insinuates itself into the concavity.

After these few words on the physical structure of the mountains, the vegetation of which it is my wish briefly to describe, it will still be necessary to devote a few minutes to the subject of climate and humidity, before I can proceed to my proper subject.

Situated in the most southern part of the temperate zone, and bounding on the north a great peninsula, which extends far into the torrid zone, the base of the Himalaya to the south possesses an almost tropical climate, tempered, however, when the sun is on the tropic of Capricorn by a moderately cool winter, and variously modified in different parts of the chain by the degree of humidity, a most important matter to be taken into consideration in every question connected with the phenomena of vegetable life.

The source of humidity in the Himalaya is almost entirely the Bay of Bengal, which is situated about 5 degrees to the south of the eastern extremity of the chain; and the wind which carries the humid atmosphere along the chain, is that which is known to nautical meteorologists as the south-west monsoon, a wind which begins to blow in the open sea about the month of April, but whose effects are not felt in the far interior before the month of June. This wind, though constant in its direction at sea, is not so in its inland course; at the head of the Bay of Bengal it is almost a south wind; it blows from the sea nearly due north towards the Himalaya, striking in its course upon the low chain of the Khasya hills, whose maximum elevation is scarcely 7000 feet.

Upon this range the first force of the monsoon is expended, and the annual fall of rain at Churra Poonjee, elevated 4000 feet on its southern slope, amounts to about 500 inches. This range, which has its origin among the mountain ranges of the south of China and north of Burmah, lies to the south of the Burrampooter, and following the course of that river, terminates in the concavity of its great bend, where it turns down toward the sea. The Khasya mountains do not, therefore, entirely run across the Bay of Bengal, so as to intercept the force of the monsoon from the whole of the Himalaya, a part of which wind, laden to saturation with moisture at a temperature of nearly 90° F., blows due north from the Bay of Bengal upon the