MY DEAR FRIEND,

WE returned to Naples, highly gratified with our expedition to Baia, and, after a day's rest, set out for Mount Vesuvius. The foot of the mountain is about six miles off. We went at night, in order to view the crater to the greatest advantage, and were about two hours in walking from the base to the hermitage. The road, although steep, is tolerably good; and a light carriage may ascend the greatest part of it.

Father Pietro, the Hermit, received us with great hospitality; and, although turned of eighty, he is by no means insensible to those charms of society which are consistent with the gravity of his order. He seemed a person of a liberal education, spoke with great judgment of the ancients, and was well informed of the state of Europe at the time of his retirement. In the course of conversation, he mentioned his having been in England, which led us to enquire in what capacity. Conceive our surprize, when this venerable sage told us that he had been a French hair-dresser! But the frankness and the grace with which he made this declaration, increased our esteem; and his conversation proved, that however low his origin, his abilities and application had raised him superior to most of us.

His habitation is a comfortable cottage, with a chapel, and a shrubbery adjoining, at the extremity of one of the small mountains, of which there are several round Vesuvius; and although half way up to the crater, this spot is secured from the lava by a ridge which separates it from the great cone; and should the burning matter run in this direction, it would be thrown on each side. But it is not impossible that he may some day be surrounded by it; and he is always exposed to the stones and ashes thrown up by the mountain.

At three o'clock the next morning we prepared for the grand ascent, but it rained so hard that our guide assured us it was impossible to proceed; and, to our infinite disappointment, the weather did not clear up till after daylight. We then took leave of our friendly hermit, and after scrambling over large fields of rough lava, in less than two hours reached the crater--an unfathomable fiery gulph, sunk from the summit of a monstrous cone, which rises above every other branch of the mountain. It emits an amazing column of smoke, so strongly impregnated with sulphur, that it was not without danger of being suffocated, that we were able to look down it, even on the side from which the wind blew.

The smoke and daylight prevented our seeing to any depth, but at night I imagine that we should occasionally have discerned fire at the bottom. We repeatedly heard a rumbling noise, not so much like that of thunder, as of a brazen carriage rolling over a bridge. These were succeeded by small explosions, which threw up large quantities of stones, accompanied by a flame, which the light prevented our seeing to advantage.

Whilst the mountain is in this dangerous state, it is impossible to measure the circumference of the crater exactly, but I am led to think that it has been exaggerated, and that it does not exceed three hundred yards. Its sides however sometimes fall in, and then the circumference may be much greater.

Figure to yourself what a volume of smoke may be emitted from such a source, and what an overwhelming torrent of liquid fire such a gulph may produce! Our shoes were burnt in getting to its edge, for it is surrounded either with new lava, or a hot, drossy substance powdered with sulphur.

Sometimes the mountain is perfectly quiet for weeks together, but it has been smoking ever since we arrived, with occasional explosions, which threaten an approaching eruption. There was a slight one a few days before we entered the bay, but the lava only descended about a mile from the crater. It is still red hot, and at night may be seen at many leagues distance.

The phenomena of lava and burning mountains have been variously explained by different philosophers. Some, and these men of reputation too, have followed the idea of the ancients, and suppose the center of the earth to be fire, to which they are so extravagant as to imagine volcanos are the chimneys. Others suppose them to be occasioned by the fermentation of firestone, sulphur, and iron, the explosions of nitre, of aqueous steam violently heated, or of air pent up and greatly rarefied. All these doubtless assist, or contribute to the formation of volcanos, but the only inexhaustible source of fire that I am informed of, is the electric fluid, whose powers were not discovered before the middle of this century. This is nothing more than the light of the sun absorbed by the earth, which of course must be again emitted, just as we receive in rain, the water and the damps he exhales from us. Whenever, therefore, the electric fluid is absorbed in larger quantities than the general outlets can return, it acts with uncommon violence, and breaks forth either by an earthquake, or an eruption. When this happens, and the eruption is not very violent, the burning matter rises gradually from the bottom to the top of the crater, and when it has filled it, it runs over like the boiling of an immense caldron. But sometimes it scorns all bounds, and the crater, monstrous as it is, being insufficient to give vent to its violence, the side of the mountain is burst open, and thrown with inconceivable force to an immeasurable height in the air. The lava then rushes forth in an impetuous torrent of liquid fire, overwhelming every thing in its course. That of 1767 was six miles long and two wide, and in some places, where it past over cavities, it was sixty or seventy feet deep.

Eruptions are generally preceded and closed by an immense discharge of stones and ashes, which often create more destruction than the lava itself.

For some time after the eruption, the lava has the appearance of melted glass, after which the upper part breaks into large pieces of a kind of dross, which, in the course of time crumble into mould, and form the richest soil imaginable, whilst the lower becomes hard stone. But this is the process of many years, and consequently great part of Vesuvius is horridly barren, whilst the rest is most beautifully cultivated.

A fog deprived us of the view from the top of the mountain; but, by what I saw at the Hermitage, I think it would have been impossible to describe it. The bay of Naples is upwards of fifty miles in circumference, and the variety of curious and beautiful objects, which strike the eye in every direction, render it one of the most pleasing and interesting sights which it is possible to behold. The capital of the kingdom is in the center, with a superb Carthusian monastery, and the Castle of St. Ilmo above it. On the west the public walk of the Chiaja, adorned with several elegant fountains, and a double row of trees. Beyond it Mount Pausilippe, with the Tomb of Virgil; the road and town of Puzzoli; the Solfaterra, and Monte Nuovo; the remains of the Lucrine Lake, and the ruins of Baia, bounded by the celebrated Cape of Misenus, and the Isle of Ischia. On the east the gardens, palace, and museum of Portici, built over the ruins of Herculaneum, Mount Vesuvius throwing forth an amazing volume of smoke in a variety of shapes, according to the wind, with its base covered with vineyards, convents, and villas, rising out of the ashes of Pompeia and Stabia. Beyond these Castello Mare, closed by the Promontory of Gampenela, and the Island of Capria. The whole country is in the highest state of cultivation, richly clothed with beautiful trees, most of which are evergreens.

The entrance of the bay is on the south-west side, and is near fifteen miles wide. Off the town there are two moles, one for the King's galleys, the other for the larger men of war and merchantmen, with three castles to defend them. But notwithstanding these works, and the Citadel of St. Ilmo, which, from its height, is unassailable, and that its garrison is sheltered by excellent casemates, I think ten sail of the line might lay this capital in ashes, as a first rate man of war may lie close to the shore.

By Sir William Hamilton's desire, we, this morning, took a boat from the Pearl, and after rowing along the west side of the town, and passing the ruins of Queen Joan's Palace, landed at a small village, he was so good as to point out to us, in the neighbourhood of which we saw the remains of Pollio's Villa, with the subterranean fish-ponds, in which he used to feed lampreys on human flesh. There are some busts of his family in the garden, and several inscriptions to remind us of his abominable luxury.