the town, there issued often, and in different parts of it, a bright pale flame, and very different from the deep red of the lava; this was occasioned by the burning of the trees that supported the vines. Soon after the beginning of this eruption, ashes fell thick at the foot of the mountain, all the way from Portici to the Torre del Greco; and though there were not at that time any clouds in the air, except those of smoke from the mountain, the ashes were wet, and accompanied with large drops of water, which, I was well assured, were to the taste very salt: the road, which is paved, was as wet as if there had been a heavy shower of rain. Those ashes were black and coarse, like the sand of the sea-shore, whereas those that fell there, and at Naples some days after, were of a light grey colour, and as fine as Spanish snuff, or powdered bark.

The breadth of the lava that ran into the sea, and has formed a new promontory there, after having destroyed the greatest part of the town of Torre del Greco, is 1204 English feet. Its height above the sea is 12 feet, and as many feet under water; so that its whole height is 24 feet: it extends into the sea 626 feet. I observed that the sea-water was boiling as in a cauldron, where it washed the foot of this new-formed promontory; and though I was at least 100 yards from it, observing that the sea smoked near my boat, I put my hand into the water, which was literally scalded; and by this time my boatmen observed that the pitch from the bottom of the boat was melting fast, and floating on the surface of the sea, and that the boat began to leak; we therefore retired hastily from this spot, and landed at some distance from the hot lava. The town of Torre del Greco contained about 18,000 inhabitants, all of which (except about 15, who from either age or infirmity could not be moved, and were overwhelmed by the lava in their houses,) escaped; but the rapid progress of the lava was such, that it ran like a torrent over the town of Torre del Greco, allowing the unfortunate inhabitants hardly time to save their lives: their goods and effects were totally abandoned; and indeed several of the inhabitants, whose houses had been surrounded with lava while they remained in them, escaped from them and saved their lives the following day, by coming out of the tops of their houses, and walking over the scoriæ on the surface of the redhot lava.

The lava over the cathedral, and in other parts of the town, is upwards of 40 feet in thickness: the general height of the lava, during its whole course, is about 12 feet, and in some parts not less than a mile in breadth. I walked in the few

remaining streets of the town, and went on the top of one of the highest houses that was still standing, though surrounded by the lava: I saw from thence distinctly the whole course of the lava, that covered the best part of the town.

On Wednesday the 18th, the wind having for a very short time cleared away the thick cloud from the top of Vesuvius, we discovered that a great part of its crater, particularly on the west side opposite Naples, had fallen in, which it probably did about four o'clock in the morning of this day, as a violent shock of an earthquake was felt at that moment at Resina, and other parts situated at the foot of the volcano. The clouds of smoke were mixed with the fine ashes, which were of such a density as to appear to have the greatest difficulty in forcing their passage out of the now widely-extended mouth of Vesuvius, which certainly, since the top fell in, cannot be much short of two miles in circumference. One cloud heaped on another, and succeeding each other incessantly, formed in a few hours such a gigantic and elevated column of the darkest hue over the mountain, as seemed to threaten Naples with immediate destruction, having at one time been bent over the city, and appearing to be much too massive and ponderous to remain long suspended in the air; it was, besides, replete with the ferilli, or volcanic lightning, which was stronger than common lightning. The enormous mass of clouds certainly rose many miles above the mountain, which appeared like a mole-hill; though the perpendicular height of Vesuvius from the level of the sea is more than 3600 feet.

To avoid prolixity and repetition, I need only say, that the storms of thunder and lightning, attended at times with heavy falls of rain and ashes, causing the most destructive torrents of water and glutinous mud, mixed with huge stones, and trees torn up by the roots, continued more or less to afflict the inhabitants on both sides of the volcano till the 7th of July, when the last torrent destroyed many hundred acres of cultivated land, between the towns of Torre del Greco and Torre dell' Annunziata. Some of these torrents, both on the sea-side and the Somma side of the mountain, came down with a horrid rushing noise; and some of them, after having forced their way through the narrow gullies of the mountain, rose to the height of more than 20 feet, and were nearly half a mile in extent.

I went on Mount Vesuvius as soon as I thought I might do it with any degree of prudence, which was not till the 30th of June, and then it was attended with some risk. It was not possible to get up to the great crater of Vesuvius, nor had any

one yet attempted it. The horrid chasms that exist from the spot where the late eruption first took place, in a straight line for near two miles towards the sea, cannot be imagined. They formed vallies more than 200 feet deep, and from half a mile to a mile wide; and where the fountains of fiery matter existed during the eruption are little mountains with deep craters. Ten thousand men, in as many years, could not make such an alteration on the face of Vesuvius, as has been made by nature in the short space of five hours.

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On the 19th, the ashes fell so thick at Somma, that unless a person kept in motion, he was soon fixed to the ground by them. This fall of ashes was accompanied also with loud reports, and frequent flashes of the volcanic lightning, so that, surrounded by so many horrors, it was impossible for the inhabitants to remain in the town, and they all fled the darkness was such, though it was mid-day, that even with the help of torches it was scarcely possible to keep in the high road. I found that the majority of people were convinced that the torrents of mud and water, that had done them so much mischief, came out of the crater of Vesuvius, and that it was sea-water.

The darkness occasioned by the fall of the ashes in the Campagna Felice extended itself, and varied according to the prevailing winds. On the 19th of June it was so dark at Caserta, which is 15 miles from Naples, as to oblige the inhabitants to light candles at mid-day; and one day during the eruption the darkness spread over Beneventum, which is 30 miles from Vesuvius. The Archbishop of Taranto, in a letter to Naples, dated from Taranto the 18th of June, said, “We are involved in a thick cloud of minute volcanic ashes, and we imagine that there must be a great eruption either of Mount Etna or of Stromboli." The Bishop did not dream of their having proceeded from Vesuvius, which is about 250 miles from Taranto. We have had accounts also of the fall of the ashes during the late eruption at the very extremity of the province of Lecce, which is still farther off; and we have been also assured that those clouds were replete with electrical matter.

Upon the whole, having read every account of the former eruptions of Mount Vesuvius, I am well convinced that this eruption was by far the most violent that has been recorded after the two great eruptions of 79 and 1631, which were undoubtedly still more violent and destructive.

The very numerous population at the foot of Vesuvius is remarkable. From Naples to Castel-a-mare, about 15 miles,

the coast is so spread with houses as to be nearly one continued street, and on the Somma side of the volcano, the towns and villages are scarcely a mile from each other; so that for 30 miles, which is the extent of the basis of Mounts Vesuvius and Somma, the population may be perhaps more numerous than that of any other spot of a like extent in Europe, in spite of the variety of dangers attending such a situation.

On Hydatids. By EVERARD HOME, Esq.-[1795.] THE animals called hydatids appear from their simplicity to be the furthest removed from the human; for as the human is the most complicated, and most perfect in the creation, the hydatid is one of the most simple, and composed of the fewest parts. It is to appearance a membranous bag, the coats of which are so thin as to be semi-transparent, and to have no visible muscular structure. From the effects produced by the different parts of this bag while the animal is alive, being exactly similar to the contractions and relaxations of the muscular fibres in the human body, we must conclude that this membrane is possessed of a similar power, and, consequently, has the same right to be called muscular. hydatid, from its apparent want of muscles, and other parts which generally constitute an animal, was for a long while denied its place in the animal world, and considered as the production of disease; we are however at present in possession of a sufficient number of facts, to ascertain, not only that it is an animal, but that it belongs to a genus of which there are several different species.

The

Hydatids are found to exist in the bodies of many quadrupeds, and often in the human: the particular parts most favourable to their support appear to be the liver, kidneys, and brain, though they are sometimes detected in other situations. One species is globular in its form, the outer surface of the bag smooth, uniform, and without any external opening they are seldom found single, and are contained in a cyst, or thick membranous covering, in which they appear to lie quite loose, having no visible attachment to any part of it. This species is most frequently found in the liver and kidneys, both of the quadruped and human subject. They vary in size; but those most commonly met with are from one quarter of an inch to three quarters of an inch in diameter.

Another species is of an oval form, with a long process, or neck, continued from the smallest end of the oval, at the termination of which, by the assistance of magnifying glasses,

is to be seen a kind of mouth; but whether this is intended merely for the purpose of attachment, or to receive nourishment, is not easily determined. This species is found very commonly in the brain of sheep, and brings on a disease called by farmers the staggers. It is not peculiar to any one part of the brain, but is found in very different situations, sometimes in the anterior, at others in the posterior lobe. It is inclosed in a membranous cyst like the globular kind; but differs from that species in one only being contained in the same cyst; and the bag, or body of the animal, being less turgid, appearing to be about half filled with a fluid, in which is a small quantity of white sediment; while the globular ones are in general quite full and turgid. This species, from its containing only a small quantity of fluid, has a more extensive power of action on the bag, and is therefore best fitted for illustrating the muscular power of these animals.

If the hydatid be carefully removed from the brain, immediately after the sheep is killed, and put into warm water, it will soon begin to act with the different parts of the body, exhibiting alternate contractions and relaxations. These it performs to a considerable extent, producing a brisk undulation of the fluid contained in it: the action is often continued for above half an hour, before the animal dies; and is exactly similar to the action of muscles in the more perfect animals. This species of hydatid is very well known by the name tænia hydatigena: it varies considerably in its size. One of those which I examined alive was above five inches long, and nearly three inches broad at the broadest part, which makes it nine inches in the circumference. The coats of the hydatid, in their recent state, exhibit no appearance of fibres, even when viewed in the microscope; but when dried, and examined by glasses of a high magnifying power, they resemble paper made on a wire frame. This very minute structure is not met with in membranes in general; it may therefore be considered as the organisation on which their extensive motions depend. The coats of the different species of hydatids had all of them the same appearance in the microscope.

The intestines, in some of the more delicately-constructed animals, have a membranous appearance, similar to the bag of the hydatid; and we cannot doubt of their possessing a muscular power, since there is no other mode of accounting for the food being carried along the canal. The action of the intestines, not coming so immediately under our observation, makes them a less obvious illustration of this principle than the hydatid; we may however consider their having a similar