supposition it will be ridiculous to imagine that they were transported thither in ships, for the conservation of their species.

We must not allow that we have no hints of this event in history; for what is plainer than this passage in Virgil ? Penitus toto divisos orbe Britannos.

May we not suppose that the word divisos may import the rending or breaking off one thing from another? And that Virgil knew its signification very well, and was well ac quainted with antiquity, and had not forgot himself? On: these words Servius says, "Because Britain was formerly joined to the Continent:" than which nothing can be more plain, than that the breaking through of this isthmus was known to the ancients.

Therefore, from the whole the Doctor concludes, that Britain was not originally an island, but became such from a peninsula; and that, as is probable, by the concurrence of some one or other of the more boisterous winds with the tides, and so breaking through the isthmus.

An Account of an Experiment to show that all Places are not equally full. By J. T. DESAGULIERS, M.A. F.R.S.

WE let fall a guinea, and two papers, in an air-pump, the one placed over, and the other under it, before any air was pumped out: the guinea came to the bottom when the papers were in the middle of the second glass from the top. Then having laid a feather on the brass springs close by the guinea, we let them loose both together; and the feather was fallen only down to the fourth part of the length of the first glass, or of the whole distance, when the guinea was got down to the bottom of the receiver. We then laid two papers and two feathers, one of each under, and the other over the guinea between the springs; and having drawn out so much of the air as to bring up the mercury in the gauge-tube, within a quarter of an inch of the greatest height to which it could be then raised by the pressure of the external air, we caused the bodies to fall all at once; and though the papers came down to the bottom at the same time as the guinea, yet the feathers, being much lighter, wanted about three inches. But at last, having laid the papers, feathers, and guinea, as before, we pumped out all the air, and then the feathers, as well as the papers, came to the bottom of the receiver at the same instant of time as the guinea.

An Account of the Skeleton of a large Animal impressed on Stone. By Dr. WILLIAM STUKELY, F.R.S.-[1719.]

AT Elston, near Newark in Nottinghamshire, was discovered an almost entire skeleton of a large animal, impressed on a very hard blue clay stone; the same as, and undoubtedly came from, the neighbouring quarries about Fulbeck, on the western cliff of the long tract of hills extending quite through the adjacent county of Lincoln. It lay, time out of mind, at the side of a well near the parsonage-house, where it had served for a landing-place to those that drew water; but on removal, the under-side exhibited this unusual form. Where the remaining part of the stone may be, which contained the upper part and continuation of the skeleton, is now utterly unknown. It seems to be that of a crocodile or porpoise. There are 16 vertebræ of the back and loins, very plain and distinct, with their processes and intermediate cartilages; nine whole or partial ribs of the left-side; the os sacrum, the ileum in situ, and two thigh-bones displaced a little; the beginnings of the tibia and fibula of the right leg; on one corner there seem to be the vestigia of a foot with four of the five toes, and a little way off an entire toe, now left perfect in the stone: there are no less than 11 joints of the tail, and the cartilages between them of a white colour distinguishable from the rest.

About six years since, I was shown many human bones taken from whole skeletons, with British beads, chains, iron rings, brass bits of bridles, and the like, which were dug up in a quarry at Blankney in Lincolnshire; which probably was plain mold when these old bodies of the Britons were interred; and since then I saw many human bones and armour, with Roman coins, fibulæ, &c. found in a stone pit in the park at Hunstanton in Norfolk, which were supposed to have been buried in the earth after a battle. Whence we may judge it a vulgar error, in the ruins of old castles and walls to admire the tenacity of the mortar, and to praise our ancestors for an art which we suppose now lost; when doubtless the strength of the cement is owing to length of time; and in future ages the same judgment may be formed of our modern buildings.

From all these instances, I infer the ancient state of these cliffs, where this skeleton was found, and shells are daily found, intimately mixed in the substance of the stone, to have formerly been of a softer consistence, capable of admitting them into its bowels, and immuring them as part of itself; and that earth which is now manageable by the plough, may

possibly, in time, assume the same density, at least not far below the surface; for in this very cliff the upper strata are still clay, becoming the harder the deeper.

Experiments made with Mons. Villette's Burning Concave. By the Rev. Dr. J. HARRIS, and Dr. J. T. Desaguliers.

THIS mirror is a concave, 47 inches wide, and ground to a sphere of 76 inches radius; so that its focus is about 38 inches distant from the vertex of the glass. The metal, of which it is made, is a mixture of copper, tin, and tin-glass, and its reflection has something of a yellow cast. The concave surface has scarcely any flaws, and those very small; -but the convex side, which is also polished, has some holes in it.

Having held several bodies in the focus of this mirror, we observed what happened to them while exposed to this great heat; and with a half second pendulum noted the time in which any material change happened to them. The experi ments were made from 9 till 12 in the morning, as follow:

No. 1. A red piece of a Roman patera, which began to melt in three seconds, was ready to drop in 100. 2. Another black piece melted at four, and was ready to drop in 64 seconds. 3. Chalk taken out of an echinus spatagus filled with chalk only fled away in 23 seconds. 4. A fossil shell calcined in seven seconds, and did no more in 64. 5. A piece of Pompey's pillar at Alexandria was vitrified in the black part in 50 seconds, and in the white part in 54. 6. Copper ore, which had no metal in it visible, vitrified in eight seconds. 7. Slag, or cinder of the ancient iron-work said to have been wrought by the Saxons, was ready to run in 29 seconds.

Here the glass, growing hot, burned with much less force. 8. Iron-ore fled at first, but melted in 24 seconds. 9. Talc began to calcine at 40 seconds, and held in the focus 64. 10. Calculus humanus in two seconds was calcined, and only dropped off in 60. 11. An anonymous fish's tooth melted in 32 seconds. 12. The asbestos seemed condensed a little in 28 seconds, but it was now something cloudy; Mons. Villette says, that the glass usually calcines it. 13. A golden marchasite broke in pieces, and began to melt in about 30 seconds. 14. A silver sixpence melted in 7 seconds. 15. A King William's copper halfpenny melted in 20 seconds, and ran with a hole in it in 31. 16. A King George's halfpenny melted in 16 seconds, and ran in 34. 17. Tin melted in three seconds. 18. Cast iron in 16 seconds. 19. Slate melted in

three seconds, and had a hole in six. 20. Thin tile melted in four seconds, and had a hole and was vitrified through in 80. 21. Bone calcined in four seconds, and vitrified in 33. 22. An emerald was melted into a substance like a turquois stone. 23. A diamond, weighing four grains, lost of its weight.

An Account of the extraordinary Meteor seen all over England, on the 19th of March, 1718-9. By Edm. HALLEY, LL.D.

OUR very worthy vice-president, Sir Hans Sloane, being abroad at that time, happened to have his eyes turned towards it at its first eruption; of which he gave the following account: That walking in the streets in London, at about a quarter after eight at night, he was surprised to see a sudden great light, far exceeding that of the moon, which shone very bright. He turned to the westward, where the light was, which he apprehended at first to be artificial fire-works or rockets. The first place he observed it in was about the Pleiades northerly, whence it moved after the manner of a falling star, but more slowly, in a seeming direct line, descending a little beyond and below the stars in Orion's belt, then in the S. W. The long stream appeared to be branched about the middle, and the meteor in its way turned pearfashioned or tapering upwards. At the lower end it came at last to be larger and spherical, though it was not so large as the full moon. Its colour was whitish, with a tint of blue, of a most vivid dazzling lustre, which seemed in brightness very nearly to resemble, if not surpass, that of the body of the sun in a clear day. This brightness obliged him to turn his eyes several times from it, as well when it was a stream as when it was pear-fashioned and a globe. It seemed to move in about half a minute or less, about the length of 20°, and to go out about as much above the horizon. There was left behind it, where it had passed, a track of a cloudy or faint reddish yellow colour, such as red-hot iron or glowing coals have, which continued more than a minute, seemed to sparkle, and kept its place without falling. This track was interrupted, or had a chasm towards its upper end, at about two thirds of its length. He did not hear any noise it made; but the place where the globe of light had been continued, for some time after it was extinct, of the same reddish-yellow colour with the stream, and at first some sparks seemed to issue from it, such as come from red-hot iron beaten on an anvil.

All the other accounts of the phenomenon, in London, agree in this, that the splendour was little inferior to that of the sun; that within doors the candles gave no manner of light, and in the streets not only all the stars disappeared, but the moon, then nine days old, and high near the meridian, the sky being very clear, was so far effaced as to be scarcely seen, at least not to cast a shade, even where the beams of the meteor were intercepted by the houses; so that, for some few seconds of time, in all respects it resembled perfect day.

Now the situation of the three cities, London, Oxford, and Worcester, being nearly on the same W. N. W. point, on which the track of the meteor had its greatest altitude above the horizon, equal to the angle of its visible way; if we suppose it at London to have been 27° high, and at the same time at Worcester to be 65° high, in the plane of the vertical circle passing through London and Worcester; supposing, likewise, the distance between them to be 90 geographical miles, or one degree and a half of an arch of a great circle of the earth, we shall, by an easy trigonometrical calculus, find the perpendicular height to have been 64 such miles.

When it first broke out over Tiverton, its diameter was half a degree; and its horizontal distance being 150 geographical miles from London, and its altitude 60, the hypothenusal, or real distance from the eye, will be more than 160 such miles; to which radius the subtense of half a degree will be above an English mile and a half, being about 2800 yards nearly. After the same manner it is difficult to assign its due velocity, while some make it half, others less than a quarter, of a minute, in passing from its first explosion to its last extinction: but the distance it moved in that time being about 3o, or 180 geographical miles, we may modestly compute it to have run above 300 such miles in a minute; which is a swiftness wholly incredible.

Of several accidents that were reported to have attended its passage, some were the effect of pure fancy; such as the hearing it hiss as it went along, as if it had been very near at hand some imagined they felt the warmth of its beams; and others thought they were scalded by it. But what is certain, and no way to be disputed, is the wonderful noise that followed its explosion. All accounts from Devon and Cornwall, and the neighbouring counties, are unanimous, that there was heard there, as it were the report of a very great cannon, or rather of a broadside, at some distance, which was soon followed by a rattling noise, as if many small arms had been promiscuously discharged. What was peculiar to this sound