Observations on Mount Vesuvius, Mount Etna, and Other Volcanos. Sir William Hamilton
the 20th, it was impossible to judge of the situation of Vesuvius, on account of the smoak and ashes, which covered it entirely, and spread over Naples also, the sun appearing as through a thick London fog, or a smoaked glass; small ashes fell all this day at Naples. The lavas on both sides of the mountain ran violently; but there was little or no noise till about nine o'clock at night, when the same uncommon rumbling began again, accompanied with explosions as before, which lasted about four hours: it seemed as if the mountain would split in pieces; and, indeed, it opened this night almost from the spot E to C (in Plate I.). The annexed plans were taken upon the spot at this time, when the lavas were at their height; and I do not think them exaggerated. The Parisian barometer was, as yesterday, at 279, and Fahrenheit's thermometer at 70 degrees; whereas, for some days preceding the eruption, it had been at 65 and 66. During the confusion of this night, the prisoners in the public jail attempted to escape, having wounded the jailer; but were prevented by the troops. The mob also set fire to the Cardinal Archbishop's gate, because he refused to bring out the relicks of Saint Januarius.
Wednesday 21st, was more quiet than the preceding days, though the lavas ran briskly. Portici was once in some danger, had not the lava taken a different course when it was only a mile and a half from it; towards night, the lava slackened.
Thursday 22d, about ten of the clock in the morning, the same thundering noise began again, but with more violence than the preceding days; the oldest men declared, they had never heard the like; and, indeed, it was very alarming: we were in expectation every moment of some dire calamity. The ashes, or rather small cinders, showered down so fast, that the people in the streets were obliged to use umbrellas, or flap their hats; these ashes being very offensive to the eyes. The tops of the houses, and the balconies, were covered above an inch thick with these cinders[10]. Ships at sea, twenty leagues from Naples, were also covered with them, to the great astonishment of the sailors. In the midst of these horrors, the mob, growing tumultuous and impatient, obliged the Cardinal to bring out the head of Saint Januarius, and go with it in procession to the Ponte Maddalena, at the extremity of Naples, towards Vesuvius; and it is well attested here, that the eruption ceased the moment the Saint came in sight of the mountain; it is true, the noise ceased about that time, after having lasted five hours, as it had done the preceding days.
Friday 23d, the lavas still ran, and the mountain continued to throw up quantities of stones from its crater; there was no noise heard at Naples this day, and but little ashes fell there.
Saturday 24th, the lava ceased running; the extent of the lava, from the spot C (Plate I.), where I saw it break out, to its extremity F, where it surrounded the chapel of Saint Vito, is above six miles. In the Atrio di Cavallo, and in a deep valley that lies between Vesuvius (1.) and the hermitage (3.), the lava is in some places near two miles broad, and in most places from sixty to seventy feet deep; at (4.), the lava ran down a hollow way, called Fossa grande, made by the currents of rain water; it is not less than two hundred feet deep, and a hundred broad; yet the lava in one place has filled it up. I could not have believed that so great a quantity of matter could have been thrown out in so short a time, if I had not since examined the whole course of the lava myself. This great compact body will certainly retain some heat many months[11]; at this time, much rain having fallen for some days past, the lava smoaks, as if it ran afresh: and about ten days ago, when I was up the mountain with Lord Stormont, we thrust sticks into the crevices of the lava, which took fire immediately: But to proceed with my journal.
The 24th, Vesuvius continued to throw up stones as on the preceding days: during the whole of this eruption, it had differed in this circumstance from the eruption of 1766, when no stones were thrown out of the crater from the moment the lava ran freely.
Sunday 25th, small ashes fell all day at Naples; they issued from the crater of the Volcano, and formed a vast column, as black as the mountain itself, so that the shadow of it was marked out on the surface of the sea; continual flashes of forked or zig-zag lightning shot from this black column, the thunder of which was heard in the neighbourhood of the mountain, but not at Naples: there were no clouds in the sky at this time, except those of smoak issuing from the crater of Vesuvius. I was much pleased with this phænomenon, which I had not seen before in that perfection[12].
Monday 26th, the smoak continued, but not so thick, neither were there any flashes of the mountain lightning. As no lava has appeared after this column of black smoak, which must have been occasioned by some inward operation of fire; I am apt to think, that the lava, which should naturally have followed this symptom, has broke its way into some deeper cavern, where it is silently brooding future mischief; and I shall be much mistaken if it does not break out a few months hence.
Tuesday 27th, no more black smoak, nor any signs of eruption.
Thus, my Lord, I have had the honor of giving your Lordship a faithful narrative of my observations during this eruption, which is universally allowed to have been the most violent of this century; and I shall be happy, if it should meet with your approbation, and that of the Royal Society, if your Lordship should think it worthy of being communicated to so respectable a body.
I have just sent a present to the British Museum of a complete collection of every sort of matter produced by Mount Vesuvius, which I have been collecting with some pains for these three years past; and it will be a great satisfaction to me, if, by the means of this collection, some of my countrymen, learned in natural history, may be enabled to make some useful discoveries relative to Volcanos[13].
I have also accompanied that collection with a view of a current of lava from Mount Vesuvius; it is painted with transparent colours, and, when lighted up with lamps behind it, gives a much better idea of Vesuvius, than is possible to be given by any other sort of painting.
I have the honor to be,
My Lord,
Your Lordship's
Most obedient
and most humble servant,
William Hamilton.
Plate I.
PLATE I.
A. Crater of Mount Vesuvius.
B. Mouth from whence came the lava of 1766; and which opened afresh, October 19, 1767, and produced the conflagration represented in Plate II.
C. The mouth which opened at 12 o'clock, October 19, 1767, whilst I was at the spot marked X; from thence came all the lava represented in Plate I.
D. The lava.
E. Mouth from whence the lava flowed at eight o'clock, October 19, when the eruption began first.
F. Chapel of Saint Vito, surrounded with lava.
1. Vesuvius.
2. Mountain of Somma.
3. Hermitage, between which and Vesuvius there is a deep valley two miles broad.
4. The Fossa Grande.
5. His Sicilian Majesty's Palace at Portici.
6. Church of Pugliano.
7. Calmaldolese Convent, near which is my Villa.
8. Saint Jorio.
9. Barra.
10. Spot, under which lies Herculaneum.
Plate II.
PLATE II.
A.