passed and returned as freely in the horizontal and pendent, as in the perpendicular branch, the growth of each would be equally rapid, or nearly so the horizontal branch would then soon extend too far from its point of suspension at the trunk of the tree, and thence must inevitably perish, by the compound ratio in which the powers of destruction, compared with those of preservation, would increase.

The principal office of the horizontal branch, in the greatest number of trees, is to nourish and support the blossoms, and the fruit or seed; and, as these give back little or nothing to the parent tree, very feeble powers alone are wanted in the returning system, No power at all had been fatal; and powers sufficiently strong wholly to counteract the effects of gravitation, had probably been in a high degree destructive. And it appears to me by no means improbable, that the formation of blossoms may, in many instances, arise from the diminished action of the returning system in the horizontal or 'pendent branch.'

The character of the wood may be very much affected by the situation in which the tree grows; and hence oak timber, which grew in crowded forests, has sometimes been conceived to be Spanish chesnut, which has happened frequently in such as was taken from old buildings in London. In such cases, the author has found the internal organization to be extremely different; and he annexes a plate for the purpose of making this difference apparent.

The remainder of this paper is occupied with some observations on the functions of the bark, and on the formation of buds in tuberous rooted plants.

CHEMICAL and MINERALOGICAL PAPERS.

Enquiries concerning the Nature of a Metallic Substance lately sold in London as a new Metal, under the Title of Palladium. By Richard Chenevix, Esq. F.R.S. & M.R.I.A.-This inge nious mineralogist has not been able precisely to ascertain the nature of this substance by analysis, but he has succeeded in forming a metallic body in every respect resembling it, and has thus shewn that what was attempted to be imposed on the public as a newly discovered simple body is in reality a compound.

The account given by the proprietors is in this paper considerably amplified by Mr. Chenevix; and the circumstances stated by them he found to be tolerably correct, except in the particular which related to its specific gravity. This he ascertained to be different in different specimens, and to vary from 10.972 to 11.482.

A great variety of experiments, in the synthetical way, discovered that Palladium is a compound of platina and mercury; which, by their union with each other, so completely

II

lost

lost their characteristic properties, as to be incapable of being detected by the usual methods.

It is not difficult to combine a small quantity of mercury with platina but to produce an alloy of these metals which shall be of so low a specific gravity as 11.3, and shall be soJuble in nitric acid, Mr. Chenevix informs us, is by no means easily accomplished. He therefore concludes that the inventor of Pailadium has some method of forming it, less subject to error than that which he has adopted. The small density of the alloy of platina and mercury is a circumstance of a very sin gular nature, but, at the same time, it accords with many other chemical facts; particularly some mentioned by Berthollet and Hatchett, where the specific gravity was very different from that of the calculated mean.

Mr. Chenevix concludes his paper by noticing the effects which anomalies, such as he has described, must necessarily have in producing a scepticism with regard to the supposed nature of many bodies that have hitherto been considered as simple.

Account of the Sinking of the Dutch Frigate Ambuscade of 32 Guns, near the Great Nore, with the Mode used in recovering her. By Mr. Jos. Whidbey, Master-Attendant in Sheerness Dock Yard, &c.-This frigate was lost by the hawse plugs not being in, and the hawse holes being pressed under water by a crowd of sail on the ship; through which a body of water got in unperceived, sufficient to carry her to the bottom. The plan adopted by Mr. Whidbey speedily and completely answered the purpose of recovering the vessel.

Observations on a new Species of Hard Carbonate of Lime; also a new Species of Oxide of Iron. By the Count de Bournon, F.R.S. & L.S.-The principal characters of the former of these substances are thus given:

Its hardness is very superior to that of common carbonate of lime, being such as to scratch very easily the fluate of lime; and, when rubbed with force upon glass, it takes off the polish of its surface, and sometimes leaves scratches upon it.

Its specific gravity, I found to be 2912.

This substance, of which I have since had an opportunity of observing a great number of specimens, I have always found to be without colour; and its crystals are very often perfectly transparent.

When powdered, and thrown upon a piece of iron heated nearly to redness, in a place that is perfectly dark, it occasions a very weak phosphorescent white light; this light is only sufficient to mark the place where the powder is thrown.

Its lustre is much greater than that of common carbonate of lime.

When put into nitric acid, a violent effervescence is produced: and it is very quickly dissolved, without leaving the smallest residuum,'

The author is inclined to suppose that this substance, and arragonite, are distinct combinations of the carbonic acid with lime: but the cause of the remarkable hardness, by which they are both distinguishable, has in neither of them been discovered.

The cubic oxide of iron is between the slightly attractable oxide, or specular iron-ore, and that kind which no longer crystallizes, except in a very indeterminate form. Its surface is of a gray colour and a specular appearance. It is not in any way influenced by the magnet, and seems to be in the lowest degree of oxidation in which iron retains the property of crystallizing in a regular form.

Its form is a perfect cube, the edges or solid angles of which are sometimes replaced by small planes.

Its fracture is conchoidal: it has a smooth grain, with a small degree of lustre; and, although it is impossible to make a regular fracture in any particular direction, yet the fracture shows that the crystalline lamina, or collection of molecules, are situated on the surface of the cube.

Its hardness is rather inferior to that of the slightly attractable oxide of iron.

Its specific gravity is very low; I found it to be only 3961. Its powder is more red than that of the slightly attractable oxide of iron, but has not the yellow cast observed in the powder of the hematite.'

ASTRONOMICAL and MATHEMATICAL PAPERS.

Yell

Account of the Changes that have happened during the last Twenty-five Years, in the relative Situation of Double Stars: with an Investigation of the Cause to which they are owing. By William Herschell, LL.D. F.R.S.-The chief object of this paper is to shew that the most simple and philosophical mode of explaining the phænomena of double stars is to suppose that the two stars, composing a double star, describe ellipses round their common center of gravity. In a former memoir, Dr. H. had shewn the mathematical and physical possibility of such a revolution; and in the present he gives an account of a series of observations made on double stars for a period of 25 years from which, he thinks, it will be manifest that these stars are not double merely in appearance, but kept together by the bond of mutual attraction. The phænomena of these double stars are very curious, and the verification of the learned author's suggestion must be highly interesting to all who are fond of philosophical inquiry.

The

The double stars offer phænomena, of which the explanation may be attempted on different hypotheses:

1. The sun and the larger of the two stars may be at rest, while the smaller is in motion.

2dly, The sun and smaller star may be at rest while the larger moves,

3dly, The sun may move, the stars of the double star being at rest; this admits of three cases, according as the angle made by the plane in which is the double star and by a line drawn from the sun to the greater star, is equal to, or less, or greater than, 90 degrees.

Lastly, The sun and the two stars may each have different

motions.

After having stated these several modes of explanation, and given schemes or tables for commodiously trying the truth of each, the author says:

The compass of this Paper will not allow me to give the observations of my double stars at full length; I shall therefore, in the examination of every one of them, only state those particulars which will be required for the purpose of investigating the cause of the changes that have taken place, either in the distance, or angle of position, of the two stars of which the double star is composed.

'As the arguments in the case of most of these stars will be nearly the same, it may be expected, that the first two or three which are to be examined will take up a considerable space; and the number of double stars, in which I have already ascertained a change, amounting to more than fifty, it will not be possible to give them all in one paper; I shall therefore confine the present one to a moderate length, and leave it open for a continuation at a future opportunity.'

Dr. H. then states his observations made on a Geminorum; and, relating the phænomena, he tries the explanation according to the first, second, and third hypothesis, shewing that in each, it is unsatisfactory. Lastly, he tries the explanation on the hypothesis of the motion of the three bodies:

In this manner, (says Dr. H.) we may certainly account for the phenomena of the changes which have taken place with the two stars of a Geminorum. But the complicated requisites of the motions which have been exposed to our view, must surely compel every one who considers them to acknowledge, that such a combination of circumstances involves the highest degree of improbability in the accomplishment of its conditions. On the other hand, when a most simple and satisfactory explanation of the same phenomena may be had by the effects of mutual attraction, which will support the moving bodies in a permanent system of revolution round a common centre of gravity, while at the same time they follow the direction of a proper motion which this centre may have in space, it will hardly be possible to entertain a doubt to which hypothesis we ought to give the preference,

F3

As I have now allowed, and even shown, the possibility that the phenomena of the double star Castor may be explained by proper motions, it will appear that, notwithstanding my foregoing arguments in favour of binary systems, it was necessary, on a former occasion, to express myself in a conditional manner, when, after having announced the contents of this Paper, I added, "should these observations be found sufficiently conclusive;" for, if there should be astronomers who would rather explain the phenomena of a small star appearing to revolve round Castor by the hypothesis we have last examined, they may certainly claim the right of assenting to what appears to them most probable.'

The Doctor next enters into a detailed examination of the several angles of position, and proves that they are such as would result from the revolution of a small star round Castor, He infers that Castor and the small star revolve about their common centre of gravity in a period of 342 years, 2 months.

In page 366, the author examines the case of y Leonis, and thinks (although the arguments are not irrefragable) that the phænomena of this double star are most reasonably explained by supposing the two stars to be united in one system,

Similarly, Bootis is examined. The phænomena of double stars are those of insulated double stars; for in the milky way. the double stars are formed by one star being placed far behind another. The remaining stars examined are Herculis, & Ser pentis, and Virginis: the first furnishes the phænomenon of the occultation of one star by another. The stars of y Virginis revolve round each other in a period of 708 years.

Account of the Measurement of an Arc of the Meridian, extending from Dunnose, in the Isle of Wight, Latitude 50° 37′ 8′′, to Clifton in Yorkshire, Latitude 3° 27′ 31′′, in Course of the Operations carried on for the Trigonometrical Survey of England, in the Years 1800, 1801, 1802. By Major William Mudge, of the Royal Artillery, F.R.S.-The first part of this Trigonometrical Survey has been already laid before the public. What is now given is made subservient to the measurement of an arc of the meridian; an important operation, and which, when repeated in different places, will enable us to judge more accurately of the earth's figure than we can at present.

The succeeding extract will shew why the longest line between North and South, that can be drawn in Great Britain, was not measured:

In a country whose surface, throughout its whole extent, is equally diversified with hilly ground, that particular part of it should be chosen, for carrying on a meridional measurement, which comprehends the most extensive arc. This arises from the necessary consequence which attends an operation in a country so circumstanced; as,

possibly,