fo, and as far as the lake of Albano, a great part of the mountain of Tivoli, together with those of Caprarola, Viterbo, &c. are compofed of feveral beds of calcined stones, pure cinders, fcorias, gravel, other materials refembling drofs of iron, baked earth, and lava, properly fo called; in fhort, all like thofe of which the foil of Portici is compofed, and thofe which iffue out of the fides of Vefuvius, under fo many different forms. One may diftinguish by the eye all these feveral fubftances: the cinders may be discovered both by their colour and taste. It is impoffible for any one, who examines with attention the productions of Vefuvius, not to obferve a perfect refemblance between them and those which we meet, every ftep we take, on the road from Naples to Rome, and from Rome to Viterbo, Loretto, &c. It follows then neceffarily, that all this part of Italy has been overturned by volcanos. These plains, which at prefent appear fmiling and fertile, covered with olive-trees, mulberry-trees, and vineyards, as are alfo to this very day even the fides of Vefuvius, have formerly been, like them, over-run with burning waves, and like them bear, not only in their bowels, but even on their furface, the veftiges of thofe torrents of fire, the billows of which are at prefent grown cold again and condensed: irrefiftible teftimonies of vaft conflagrations anterior to all hiftorical monuments.

the tour of Naples. He afferts that all iflands and mountains wherein are found marine bodies, and of course the continents which ferve as bafes to thefe mountains, have all fprung out of the bofom of the deep, by the efforts of fubterranean fires. Hiftory furnishes him with proofs for a pretty confiderable number: the rest he concludes by induction. His affertion, the truth of which I am unwilling to deny, is too general to be completely proved: I confine my own to fimple facts, and draw from thence only the neceffary confequences. When I fee in an elevated plain a circular bason furrounded with calcined rocks, the verdure with which the neighbouring fields are covered impofes not on me; I inftantly perceive there the ruins of an ancient volcano, as I fhould perceive beneath the fnow itself the traces of an extinguifhed fire, on feeing an heap of cinders or coal. If there be a breach in this circle, I ufually find out by following the declivity of the ground, the traces of a rivulet, or the bed of a torrent, which feems, as it were, hollowed in the rock; and this rock when examined clofely, appears frequently to be nothing more than lava, properly fo called. If the circumfe rence of the bafon has no breach,. the rain and fpring waters which affemble there and have no issue, generally form a lake in the very mouth of the volcano.

The reprefentation alone, on a topographical chart, of the lake of Albano, with its steep fides and circle roughened with rocks, called to my remembrance the lake of Quilotoa, which I have elfe

where described, and whofe waters fometimes exhale fumes of fire. A few days after, the fight of the lake of Albano itself, and the calcined matter with which its banks are powdered, left me no room to doubt any longer of its origin. I faw manifeftly the profound funnel of the fhaft of an ancient volcano, in the mouth of which the waters had accumulated themfelves. Its eruption, of which hiftory makes no mention, must have been anterior to the foundation of Rome, and even of Alba, from whence this lake has taken its name, a period amounting to near 3000 years.

At the fight of the traces of fire diffused in the environs of the lakes of Borfello, Rerfiglione, and Bracciano, on the road from Rome to Florence, I had formed the fame conjectures, before I had seen either Vefuvius or the matter which it vomits forth. I pafs the fame judgment by analogy on the lake of Perugio, and feveral others in the interior parts of Italy, which I know only by the map.

In fhort, I look upon the Apennine as a chain of volcanos, like that of the Cordilleras of Peru and Chili, which runs from north to fouth, the whole length of South America, from the province of Quito to the Terra Magellanica. The course of the volcanos of the Cordilleras is interrupted: a great number of them are either extinguished or smothered; but feveral ftill remain actually burning. The old ones alfo frequently revive, and fometimes new ones are kindled even in the bottom of the fea; nor are their effects, on that account, lefs fatal. In a few

years time both Lima and Quito, two capital cities of Peru, became the victims of these two kinds of volcanos. The chain of thofe of the Apennine, which divides the continent of Italy, in like manner from north to fouth, and extends as far as Sicily, prefents us ftill with a pretty great number of vifible fires under different forms; in Tufcany, the exhalations of Firenzuola, and the warm baths of Pifa; in the ecclefiaftical fate, those of Viterbo, Norcia, Norcera, &c. in the kingdom of Naples, thofe of Ifchia, Solfaterra, and Vefuvius; in Sicily, and the neighbouring ifles, Etna or Mount Gibel, with the volcanos of Lipari, Stromboli, &c. But other volcanos of the fame chain being either extinct or exhaufted from time immemorial, have left only fome remains behind; which, although they may not always ftrike at the first fight, are not at all less diftinguishable to attentive eyes. In fhort, the earthquakes which have at various times overturned feveral of the cities of Italy and Sicily, that which fwallowed up the city of St. Euphemia in 1638, and of which Kirker has drawn fo pathetic a picture, that which deftroyed Catano in 1693, that which opened the gulfs of Palermo in 1718, that which fince the reading of this memoir has overturned Syracufe, recall to my remembrance the difafters of Valparaifo, Callao, Lima, and Quito, in South America, and close the parallel between the Cordilleras of Italy and those of Peru: the marks of refemblance between them are but too ftriking.

Multiplication

Multiplication of Species in the vegetable kingdom, inftanced in the

I

nectarine.

Was vifiting, last fummer, at Thomas Wood's, Efq; at Littleton, near Sunning, in Middlefex; who taking me into his garden, told he would fhew me a great curiofity: and immediately leading me to a large peach-tree, he fhewed me, on one little twig, a peach and nectarine growing clofe together.

This amazed me: I had, indeed, before heard, from perfons of undoubted probity, that a particular branch of a peach-tree had fometimes bore nectarines: but here the wonder was increased, for two distinct different fruits are feen on the fame twig.

I knew my worthy friend, Mr. Wood, was a gentleman of too much honour and veracity to deceive me. Yet, to fatisfy my curiofity, I carefully examined the tree, and found not the leaft reafon to fufpect any fallacy.-The twig, for fo I must call it from its fmallnefs, projected from the ftem of the tree about the length of my finger; on one fide was a fair rough peach, and close on the other fide of the fame twig was a fair smooth fhining nectarine.

Having ftrictly related the fact, I fhall fubmit the cause of this phænomenon to the judgment of others.

This conclufion, however, I draw from it, that the peach is the mother of the nectarine; and what confirms my notion, is, that I have not found yet an ancient Latin name for the nectarine, which could fcarce happen, if it was not a more modern fruit than the peach.

Parkinfon, in his Paradifus, gives it a name of his own (nuxperfica) which may be given with as much propriety to the peach as the nectarine. He fays, Mathiolus mentions it; but I have not that author.

1

It is, I think, probable, that fome ingenious people, having obferved this lufus naturæ, and taken buds from the nectarine branch, and inserted them into proper ftocks, thus began the race of nectarines, and afterwards increafed the forts by fowing ftones.-I have a young nectarine-tree, that came up from an accidental ftone that fowed itself, and bore fruit this year.

I was at firft led to think, that this uncommon production happened from the fimilitude of the organs of generation in the peach and nectarine. Being both fpecies of the fame genus, and growing in the fame garden, I thought the prolific powder of the nectarine might impregnate the ovary of the peach, and, from that accident, the fruit might be changed to a nectarine: but this will not account for the firft phænomenon of the kind, which, if my conjecture above, concerning the origin of the nectarine, is true, must have happened before any trees bearing nectariues only were in being.

I am informed, that the like mixt production happened at lord Wilmington's at Chifwick.

And thus in orchards amongst apple-trees, a mixture of fruit hath been obferved on the fame tree, fuppofed by the fporting of the farina.-See Vol. X. of Martin's Abridgment of the Philof, Trans,

Experiments to prove that water is not incompresible; by JOHN CANTON, M. A. and F. R. S. from Part II of the Philofophical Tranfactions for the year 1762.

HAVING procured a fmall glafs

tube of about two feet in length, with a ball at one end of it of an inch and a quarter in diameter; I filled the ball and part of the tube with mercury; and keeping it with a Farenheit's thermometer, in water which was frequently stirred, it was brought exactly to the heat of fifty degrees; and the place where the mercury ftood in the tube, which was about 6 inches above the ball, was carefully marked. I then raised the mercury, by heat, to the top of the tube, and fealed the tube. hermetically; and when the mercury was brought to the fame degreat of heat as before, it ftood in the tube of an inch higher than the mark.

32

Too

The fame ball, and part of the tube being filled with water exhaufted of air, inftead of the mercury; and the place where the water stood in the tube when it came to reft in the heat of 50 degrees being marked, which was about fix inches above the ball; the water was then raised by heat till it filled the tube; which being fealed again, and the water brought to the heat of 50 degrees as before, it ftood in the tube 4 of an inch above the mark.

Now the weight of the atmofphere (or about 73 pounds avoirdupoize) preffing on the outfide of

the ball and not on the infide, will squeeze it into lefs compafs*. And by this compreffion of the ball the mercury and water will be equally raised in the tube: but the water is found, by the experiments above related, to rife of an inch

more than the mercury, by re

moving the weight of the atmosphere.

6

In order to determine how much water is compreffed by this or a greater weight, I took a glafs ball of about an inch and in diameter, which was joined to a cylindrical tube of four inches and in length, and diameter abont of an inch; and by weighing the quantity of mercury that exactly filled the whole length of the tube; I found that the mercury in an inch of the tube, was the 100,000th part of that contained in the ball; and with the edge of a file, I divided the tube accordingly.

of

This being done, I filled the ball and part of the tube with water exhaufted of air; and left the tube open, that the ball, whether in rarefied or condenfed air, might always be equally preffed within and without, and therefore not altered in its dimenfions. Now by placing this ball and tube under the receiver of an air-pump, I could fee the degree of expanfion of the water, anfwering to any degree of rarefaction of the air; and by putting it into a glass receiver of a condenfing engine, I could fee the degree of compreffion of the water, anfwering to any degree of condenfation of the air. But great care must be taken in

making

making thefe experiments, that the heat of the glass ball be not altered, either by the coming on of moifture, or its going off by evaporation; which may eafily be prevented by keeping the ball under water, or by ufing oil only, in working the pump and condenfer.

In this manner, I have found by repeated trials, when the heat of the air has been about 50 degrees, and the mercury at a mean height in the barometer, that the water will expand and rife in the tube, by removing the weight of the atmosphere, four divifions and or one part in 21,740 and will be as much compreffed under the weight of an additional atmosphere. Therefore the compreffion of water by twice the weight of the atmosphere, is one part in 10,870 of its whole bulk. The famous Florentine experiment, which so many philofophical writers have mentioned as a proof of the incompreffibility of water, will not, when carefully confidered, appear fufficient for that purpose: for in forcing any part of the water contained in a hollow globe of gold through its pores by preffure, the figure of the gold must be altered; and confequently, the internal

space containing the water, di minifhed; but it was impoffible for the gentlemen of the academy del Cimento to determine, that the the water which was forced into the pores and through the gold, was exactly equal to the diminution of the internal space, by the preffure.

Account of a boy furviving the lofs of a confiderable portion of the brain.

T

Homas Walker, a child about

fix years of age, living at Caton near Lancafter, being afleep near the fire, a ftone about half a hundred weight fell from the top of the chimney upon the fide of his head, and fractured his fkull in a moft terrible manner. The poor boy lay as dead for feveral hours; but his parents being perfuaded to carry him to Dr. Brachen of Lancafter, they immediately followed the advice. The doctor made a proper incifion, in order to clear the fkull from the pericranium, and difcover the fracture; when he found the parietal bone fractured in twenty pieces (fome as large as a fhilling piece) with their fharp points fticking down in the brain;

the

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and 6