ance of any external injury. The pearls are solid and nearly orbicular, with a small pedicel, which is continued so as entirely to cover the wire. They may be perforated and used so as to show their whole surface, which I did not expect could ever be the case with any artificial pearls; but they must, doubtless, unlike the artificial pearls formed by the other means, be a considerable time in coming to any useful and valuable size.-Ann. Phil. N. S. x. 389.

9. Flying-Fish in the Channel.-Sir-In going down channel on the 23d of August last, with light winds from the E.N.E., inclinable to calm, when off Portland, we were surprised by the appearance of a rather large shoal of what is commonly called the flying-fish. They were evidently closely pursued by some one of their numerous enemies, from the frequent and long flights which they took; but it was impossible to discover what he was, though passing close to the vessel.

I am not aware that I have ever heard of this fish having been seen in the English Channel before; and the fact may possibly interest some of your numerous scientific readers.

Sunderland, Dec. 2, 1825.

J. C. W.

10. Age of a Yew-tree.-In the original charter for building the church of Peronne, in Picardy (now the department of Somme), dated in the year 634, a clause was inserted, directing the proper preservation of a yew-tree, which was in existence in 1790, about 1150 years after this notice of it in the charter.-M. M., lx. 359.

11. Phosphate of Lime accompanying Iron-Stone in Coal-beds. (Allier.)-MM. Manby and Wilson sent various specimens of minerals, which were proposed to be worked for iron, to the school of Mines; and one of them, being examined by M. Berthier, proved to be a new variety of phosphate of lime. This observation is of considerable interest as relating to the source of phosphorus sometimes found in iron obtained from the argillaceous iron-ore.

"Among these specimens," says M. Berthier," one was found which contained very little iron, and which I soon ascertained to be principally composed of phosphate of lime: this specimen had exactly the same appearance as the argillaceous carbonate of iron, and the ticket accompanying it indicated that it was found in the same circumstances, i. e., in lumps in the bituminous schist accompanying the coal. It was lenticular, about the size of the fist, homogeneous, and fine-grained, having some degree of lustre in a bright light, and of a deep gray colour. The argillaceous carbonate of iron of the coal-formations often contains phosphoric acid, even in considerable proportions; but pure phosphate of lime has never before been observed in these circumstances."

"The specimen of the phosphate of lime of Fins gave by analysis

Heated in a crucible lined with charcoal, it fused into a compact mass, opaque, stony, covered on its surface with grains of a brittle metallic substance. Fused with half its weight of borax, it produced a vitreous enamel like scoria, and very brittle grains, almost unacted upon by the magnet.'

"

A note by M. Guilleman on the same substance, describes it as occurring in globular nodules, sometimes flattened, and generally of small size. They are found in abundance in the black argillaceous schists; they are not homogeneous, but are enveloped in carbonate of iron; sometimes they are internally divided by laminæ of carbonate of lime or of coal: at other times they are enveloped in a zone of compact sulphuret of iron. In the centre is a dirty yellow, or gray nucleus, compact, finely granular, and traversed by graminous impressions; it is this nucleus which contains the phosphate of lime. One specimen of sp. gr. 2.65 was composed of phosphate of lime

carbonate of iron

0.863

. 0.117

but the proportions vary in different specimens.-Ann. des Mines,

xi. 143.

12. Geology of the Severn. The Rev. C. P. N. Wilton, F.C.P.S., &c., has lately been engaged in making a geological survey of the shores of the Severn, in that part of its course which passes through the parish of Clure, in Gloucestershire, to an extent of about 7 miles. In this examination several interesting discoveries were made, of which detailed accounts will shortly be laid before the public.

In one place a stratum was found of a sort of carbonized wood, much resembling Bovey coal, in which occurred, disseminated in small pieces, a white substance not hitherto met with in that matrix, and which, upon examination by Mr. Brande, was found to be sulphate of barytes.

A fossil species of alcyonium was met with in blue lias. A circumstance regarded as extremely curious, when mentioned to that VOL. XX. 2 F

zealous naturalist, Mr. Miller of Bristol, (author of the Natural History of the Crinoidea, &c.) With this were found immense specimens of cornu ammonis, &c.

Near the same spot a great number of bones were met with in diluvial gravel; a large fragment of a gigantic stag's horn: seven fragments of immense jaw-bones, and teeth in great quantities.

At no great distance some remains of antiquity were discovered. A sort of burying-place has been distinctly traced out. Wood ashes, iron nails, and rùde implements, with portions of red and black pottery, were dug up, and at about 2 miles' distance, fragments of the same pottery were found mixed with a quantity of iron-slag.

In another spot, on the banks of the Severn, in a bed of clay, 9 feet below the surface, was dug up, a sort of iron shovel, much corroded, accompanied by fragments of red pottery, and wood in a state resembling coal.

13. On the "Extraordinary rise of the Rio de la Plata," and on the Storms of that part of South America.

SIR,-In the last Number of the Journal of Science and the Arts, p. 183, my attention was arrested by an article extracted from the Edinburgh Phil. Journal, which, to most nautical or scientific men, and particularly so to those who have visited the part of South America alluded to, cannot but appear somewhat astonishing. I mean that headed "Extraordinary Rise of the Rio de la Plata," which is thus described:

"This river, as is well known, is flooded at certain periods; and, like the Nile, inundates and fertilizes the country. The Indians then leave their huts and betake themselves to their canoes, in which they float about until the waters have retired. In April, 1793, it happened that a violent wind heaped up the immense mass of waters of this river to a distance of ten leagues, so that the whole country was submersed; and the bed of the river remained dry, in such a manner that it might be walked over with dry feet. The vessels which had foundered and sunk were all exposed again; and there was found among others, an English vessel which had perished in 1762, &c. &c.

Now, supposing that water has always a natural tendency to find its own level, it will appear rather strange how the adjacent lands could possibly be submersed to such an extent as is here described, or to any extent at all; and the bed of the river at the same time be left dry, which certainly possesses a much lower level, as also a greater declivity towards the sea than the face of the neighbouring country. The first part of the paragraph will convey very unexpected and pleasing intelligence to the inhabitants of the right bank; for so far from the river being flooded at certain periods, and then, "like the Nile, fertilizing the country

which it inundates," this event occurs at very uncertain periods, sometimes carrying away with it, or spoiling not only the accumulated produce, but also the growing harvest of the peasant; and even then, I conceive, the fact of its being any advantage to the soil more than doubtful. That some few of the natives may, on such occasions, be obliged to retire with their families to their boats, is possibly true; but generally speaking, and particularly so in the villages, the houses are of two stories, and when washed out of the basement, they coolly retire to the one above: and so situated, all communication between the different houses is in course effected by canoes or boats. This is particularly the case at Ensinada; a spot perhaps the most liable of all others in the Plate to inundation; and where, as if the genius of folly and stupidity was destined to control every step of that ill-fated expedition, from its arrival in the river to its departure, the quondam General Whitelock, thought proper to effect his landing. The natural consequence of which step was, that he lost all his carriage-guns in the intervening marshes between that village and the Barraccas.

The fact is simply this; the tides in the Plate being extremely weak, the stream is powerfully acted upon by the prevailing winds and the waters increased or otherwise, in proportion to their strength and duration. Thus, a strong and long-continued easterly wind will, by assisting the flow from the ocean, and proportionably retarding the body of fresh water from the many tributary streams on the upper part of the river, always occasion a considerable rise: and after heavy rains, when the freshes come down strong, will frequently inundate most of the low lands on the right bank. The left bank of the river is higher; in some places, (Monte Video, for instance,) almost mountainous : I should, perhaps, rather say hilly: and is, consequently, less subject to inundation.

The westerly winds, on the contrary, which are the most remarkable and powerful in this part of South America, impelling by their violence the body of water from the upper part of the river towards the sea, much faster than its place can be supplied from the tributary streams, will cause a sudden fall of the water, frequently of several feet. And, even after the first violence of the storm has passed away, should the wind continue from the same quarter, it will, perhaps, be days before the river attains again its usual depth. It was, in consequence of a storm of this description in 1793, (a most violent pamparro,) that the extraordinary fall alluded to in the paragraph above quoted, occurred; and which I have frequently heard described at Buenos Ayres by those who had witnessed it; but I never before heard that the country was at the same time inundated. Indeed it usually happens on such occasions, that the small streams which

empty themselves into the Plate are left entirely dry; and I have frequently found the little harbour of Ensinada rendered difficult of access even by a boat; while the Barraccas, which with easterly winds have known to receive a light ship of five hundred tons, after a strong westerly wind, scarcely possible to be entered with a canoe. It should be observed, that the river between Buenos Ayres and Monte Video is excessively shallow, having barely three fathoms with ordinary tides, in the channel, which is also narrow, The middle of the stream is filled with extensive, dangerous, and, I should think, increasing banks, having only a few feet water upon them, and with low tides are frequently dry.

The wind above alluded to, is called by the natives Pamparro, from Las Pampas, those immense plains which it traverses in its course; throughout which it takes up, and carries with it through the air large quantities of sand, soil, and vegetable refuse. Meeting with nothing throughout the immense space, and to the traveller, apparently interminable level, capable of arresting its progress, or diverting its direction; it rolls on, gathering increased strength, density, and velocity in every league; throwing down houses, and frequently scattering ruin and destruction upon the villages over which it passes. To the seaman, who is unacquainted with the coast, these storms are particularly dangerous, as they generally come from the opposite direction to that from whence the wind is blowing; and are seldom preceded by any warning calm, or threatening appearance of the atmosphere, but burst at once with terrific violence upon the unsuspecting mariner, who may thus, if unprepared to resist its fury, see in one moment his lofty ship a wreck upon the face of the waters. One circumstance alone gives the experienced seaman or landsman warning of its approach. A slight arch of dusky white is first discerned in the horizon; this increases, and expanding as it approaches, the clouds, of which it appears composed, roll gradually towards you. Meanwhile the atmosphere is clear, even perhaps within the circumference of the threatening arch, and the wind steady from the opposite point from which the danger is to be apprehended. At length the hollow murmuring of the approaching storm is heard; and in a moment it bursts? upon you in all its violence, covering the decks with sand and dirt, even when many leagues from the land. Happily, the extreme violence of these winds is seldom of long duration, scarcely ever lasting more than half an hour, when they subside; frequently, however, ending with a strong gale from the same quarter of the compass.

I remember in 1808, when in his Majesty's late ship the Agamemnon, in going down the coast from Rio de Janeiro, wed experienced, for the first time, the effects of a Pamparro...The: