and explained several phenomena which had been described in some of his preceding papers. He showed, likewise, that a thermometer might be constructed by means of the different coloured fringes exhibited by plates of glass of various degrees of heat. This thermometer might be made capable of indicating a change of temperature not exceeding one degree of Fahrenheit's thermometer.

At the same meeting a paper by Sir Humphry Davy was read, giving an account of a new method of preventing explosions in coal-mines from fire-damp. His method is to surround the flame of the lamp or candle with a wire sieve, the meshes of which amount at least to 250 in an inch. Such a sieve completely prevents the explosion from setting fire to the gas on the outside of it, even though the most inflammable mixtures of gases, as oxygen and hydrogen, be present. This is certainly one of the most extraordinary and unaccountable facts connected with the propagation of heat and combustion. It is possible (supposing the fact to be correct) that so great an attraction may exist between the wires and the air surrounding them, that the internal combustion and expansion is not able to displace it. If we suppose such a fixedness to exist, it would account for the explosion not kindling the surrounding mixture on the outside of the sieve. This contrivance (supposing it effectual) would completely answer the purposes of the miner. Such sieves might be made for a halfpenny apiece, and they would not in the least obstruct the light, or prevent the candle from being used by the miner as it is at present; whereas the bulk, and little light given out by the lamps, constitutes a serious objection to their use.

LINNEAN SOCIETY.

On Tuesday, Dec. 5, the remainder of Dr. Acharius's paper describing two new genera of lichens was concluded.

A curious paper was likewise read, giving an account of the ancient inhabitants of Guadaloupe near the spot where the fossil human skeleton was found. Two different tribes existed, to whom the writer of the paper gives the names of Caribes and Galipees. About the year 1710 they quarrelled, and a battle was fought between them on the spot where the skeleton was found. The Galipees were routed, and disappeared in consequence, having no doubt emigrated. The author seems to conceive that the skeletons of the warriors slain in that battle were speedily encrusted with the calcareous sand of the place, and that this recently formed stone constitutes the rock in which the fossil skeleton was found.

On Tuesday, Dec. 19, a paper was read endeavouring to explain the way in which the rock containing the Guadaloupe skeleton was agglutinated. It contained, likewise, an enumeration of the different species of shells and madrepores the fragments of which occur in the rock.

At the same meeting a paper by Dr. Macbride, of South Carolina, was read, giving an account of the fly-catching qualities of the leaves of the Suracenia flava and adunca. These leaves constitute

a kind of tube with an operculum at the top. They contain a saccharine liquid which allures the insect. It lingers some time on the margin of the leaf, but at last ventures in, and is drowned in the liquid, being unable to make its way up the tube, which is beset with hairs pointing downwards, and preventing its escape. The number of flies destroyed by falling into these leaves is very great. They are sometimes placed in rooms for the purpose of getting rid of flies.

On Tuesday, Jan. 16, 1816, a paper by M. Richard, of the French Institute, was read, containing a description of two new species of American plants, the xylopia sericea and oxandra laurifolia.

GEOLOGICAL SOCIETY.

June 16, 1815.-A paper, entitled Description of a New Ore of Tellurium, by Professor Esmark, of Christiana (accompanied by a specimen), was read. This ore occurs in hexagonal plates, of a tinwhite colour. When exposed to the blow-pipe, it exhibits all the characters of tellurium, and there remains behind a globule of silver. It is found in the Oundal copper-mine, accompanied by copper pyrites and by molybdena.

A paper on the analysis of a Swedish mineral, supposed to be felspar, by John F. W. Herschell, Esq. was read. The former part of the paper consists of observations, supported by examples, for the purpose of showing that silica acts as a weak acid in the composition of mineral substances, and that it combines with the other earths, and with metallic oxides, in definite proportions. The mineral itself, a detailed account of the analysis of which is given in the latter part of the paper, approaches nearly in its composition to fibrolite, its ingredients with their proportions being as follows :)

A letter from S. Solly, Esq. to the Junior Secretary, dated Christiana, Dec. 6, 1814, was read. In this letter some particulars relative to the junctions of the shell lime-stone and trap in the vicinity of Christiana are related, and their application to a particular theory of Mr. S. on the origin of the compact and porphyritic traps.

A paper, entitled An Account of some Attempts to ascertain the Angles of the Primitive Crystals of Quartz, and of the Sulphate of Barytes, by W. Phillips, Esq. M. G. S. was read. M. Hay, in his Tableau Comparatif, has stated the angles of the primitive crystals of quartz at 94° 24′ and 85° 36'.

Mr. Phillips, in his trials with the reflecting goniometer on some

hundreds of small brilliant crystals from Norway, from Spain, and from Bristol, did not find a single crystal in which the measurement of the angles precisely correspond with those determined by Haüy, nor did he meet with a single example of perfect coincidence among the corresponding angles of any one crystal. The only measurements in which several specimens agreed were 94° 15′ and 85° 45'; and these, therefore, Mr. P. is inclined to consider as approaching nearer to the true dimensions of the primitive rhomboid than any other. This want of coincidence in the measurements of crystals which were selected on account of their brilliancy and seeming perfection, induced Mr. Phillips to subject to similar examination some remarkably fine crystals of sulphate of barytes, and in these also a similar disagreement in the dimensions of the same angle in different crystals was found to occur, amounting to at least 26'. He then examined some good cleavages in the direction of the primitive planes, and found six of them agree perfectly in giving 101° 42′ for the obtuse angle, and 78° 18' for the acute angle, of the primitive rhomb; a result differing materially from that of Hauy, who states them to be 101° 32′ 13′′ and 78° 27′ 47′′.

A communication from Dr. Berger, of Geneva, was read. In this paper Dr. B. describes the scapula of some unknown large animal which was recently found in the lake of Geneva.

Nov. 3.-A paper from G. Cumberland, Esq. on certain organic remains found near Weston Super Mare was read. Closely adjacent to Weston Super Mare is a promontory, the summit of which is occupied by a Roman station called Whorlbury Camp; and at the northern extremity of this promontory is a small rocky island, resorted to by fishermen at low water. A narrow horse road leads from the downs above to this island; on the left hand of which, opposite to the sea, may be observed a bed of soft red sand-stone interstratified with others of hard red marl. The entire thickness of these beds is about six feet, they dip at an angle of about 47°, and rest on a grey lime-stone destitute of shells. In the marly part of these beds occur numerous substances, resembling pieces of bamboo separated at the joints. Their length rarely exceeds five inches, but their thickness varies from a quarter of an inch to five inches. Their substance appears to be red clay, more or less penetrated by quartz. There is no apparent passage from one joint to the next, although the ends are often in contact; from which circumstance Mr. C. concludes them to be real vegetable remains. These same substances also occur at Uphill, on the opposite point of Weston Bay, but are there imbedded in a coarse grey shell lime-stone. Just over the outburst of these beds at Whorlbury Camp is a pale yellow sand-stone, containing long white stalks of Abayonia, which when in fragments might easily, from their cellular structure, be mistaken for fossil bones.

In another letter, addressed to the Secretary, Mr. Cumberland mentions the discovery of a new and very elegant bottle encrinite in the black rock of Bristol.

A paper, entitled Some Observations on the Salt Mines of Cardina made during a Tour in Spain in the Summer of 1814, by Dr. Traill, was read. From the bank of the river Cardonero, near the town of Cardona, in the province of Catalonia, a small valley extends for about half a mile in a direction from E. S. E. to W. N. W., bounded by steep and lofty ridges, of a coarse yellowish grey micaceous sand-stone. The bottom and immediate sides of the valley consist of reddish-brown clay, from which large imbedded masses of rock salt project in the manner of more ordinary rocks. At the upper extremity of the valley is a rugged precipice from 400 to 500 feet in height, of greyish-white salt, being perhaps partly natural, but principally artificial, as it forms the side of the great quarry from which this valuable mineral has been extracted during many ages. The lowest part of the present works has a solid floor of pure salt, and is nearly on a level with the bottom of the valley, where no salt occurs, but the real depth of the bed has not been ascertained. The surface of the precipice of salt, which has been long exposed to the weather, is furrowed by innumerable shallow tortuous channels, divided from each other by their edges, often so sharp as to cut the hands like broken glass. This appearance is evidently produced by the winter rains, which in their descent along the face of the rock become nearly saturated with the salt which they dissolve. The general colour of the exposed surface is greyish white, tinged here and there of a pale reddish brown by the intermixture of clay. Towards the extremities of the rock extremely thin layers of plastic clay are insinuated between layers of salt, giving the mass a waved and striped appearance. The fracture of the salt is highly crystalline, and usually exhibits large grained distinct concretions. A brine spring flows out at the foot of the great precipice, the water of which is probably almost saturated, since the channel which it has worn in the salt, over which it has flowed for many years, is not more than two feet wide, and less than a foot in depth. No specimens were observed by Dr. T. of the fibrous variety of salt, nor was there the least appearance of gypsum in the neighbourhood. The salt is quarried by wedges and pickaxes, and when ground in a common mill is perfectly white and fit for

use.

Dec. 15.-The reading of Dr. Berger's paper on the Physical Geography of the County of Donegal, in Ireland, which had occupied the Society during the two preceding meetings, was concluded.

The county of Donegal presents an area of about 2,000 square miles, of very varied surface. By far the greater part of this is occupied by primitive rocks, which, rising to considerable elevations above the level of the sea, constitute a very distinct chain of mountains, about 54 miles in extreme length from N. E. to S. W. This chain is itself composed of six nearly parallel and equidistant lines, the entire breadth of which may be stated on an average at about 15 miles. The northernmost parallel, ranging about three miles from the coast, extends from Sheephaven to the Bay of

Giddore. It is composed of several mountainous elevations, more or less connected together; some of which are round backed, do not exceed 800 feet in height, and consist of green-stone; while the others have long flat summits subsiding to the S. W., attain in some parts an elevation of 1,200 feet, are excessively barren, and consist of quartz rock. Of these latter the most remarkable is Caintrena mountain.

The second parallel runs about three miles south of the first, including most of the highest mountains of the county, and is almost wholly composed of quartz rock. It forms a continuous line from Muckish to Arigie, of which the principal summits are Muckish mountain, 2,100 feet high, and exhibiting on its south-western side a wall of quartz rock nearly 1,400 feet high; the three mountains called Aghla, the highest of which rises about 1,900 feet above the sea; and Arigie, the loftiest in the county, being at least 2,400 feet in height.

The third parallel lies at the distance of two or three miles south of the second, and consists entirely of gneiss. It presents roundbacked hills more fertile than the quartz rock mountains, and for the most part of inferior elevation. The two mountains, however, of the name of Slieve-Snaght, which belong to this range, must be considered as exceptions with regard to the last particular, as the lower of them is nearly 1,900, and the higher exceeds 2,100, feet in height.

The fourth parallel, almost adjacent to the third, is, like that, composed entirely of gneiss. It is of inferior elevation, the loftiest summit not exceeding 1,700 feet. In parts it is covered by bog; but, upon the whole, offers a large extent of good pasturage.

The fifth parallel is the longest, but the most interrupted, of any. It commences with Binnion Hill, in Innishaven, and extends as far as the entrance of Lough Sivilly. The whole of this range is quartz rock; the summits vary in height from 800 to 1,700 feet, the latter of which is the elevation of Aghla-more, the principal mountain of the line.

"

The sixth parallel consists of groups loosely connected with each other, some of which (and those the highest) consist of quartz rock. Of these latter Dooghrsey, 2,195 feet above the sea, is the most

remarkable.

The spaces which separate the above-mentioned lines of mountain from each other form longitudinal vallies, the course of which nearly corresponds with the bearing or dead level of the strata. From each opening of the valley the ground rises more or less rapidly, but in an unequal proportion, till it attains the summit level in which various springs originate, the waters of which run N. E. and S. W., and are augmented in their progress by the streams discharged into them from the transverse valleys, by which latter the continuity of the main ridges is more or less interrupted. The summit level of the valley between the first and second lines of mountains is 347 feet above the level of the sea; of that between