VOL. LVIII.J PHILOSOPHICAL TRANSACTIONS. 4^5 



Before 8 in the morning, the mountain had opened a mouth, without noise, 

 about 100 yards lower than the ancient crater, on the side towards the Monte di 

 Somma : as soon as it had vent, the smoke no longer came out with that violence 

 from the top. On a sudden, about noon. Sir W. heard a violent noise within 

 the mountain, which split ; and, with much noise, from this new mouth a foun- 

 tain of liquid fire shot up many feet high, and then like a torrent rolled on 

 directly towards him. The earth shook, at the same time that a volley of pu- 

 mice stones fell thick upon him ; in an instant, clouds of black smoke and ashes 

 caused almost a total darkness ; the explosions from the top of the mountain 

 were much louder than any thunder he ever heard, and the smell of the sulphur 

 was very offensive. About 2 in the afternoon another lava forced its way out of 

 the same place as the lava came last year, so that the conflagration was soon as 

 great on one side of the mountain as on the other. 



The noise and smell of sulphur increasing. Sir W. removed from his villa to 

 Naples ; and he thought proper, as he passed by Portici, to inform the court of 

 what he had seen ; and humbly offered it as his opinion, that his Sicilian majesty 

 should leave the neighbourhood of the threatening mountain. However, the 

 court did not leave Portici till about 12 o'clock. Sir W. observed, in his way to 

 Naples, which was in less than '2 hours after he had left the mountain, that the 

 lava had actually covered 3 miles of the very road through which he had retreated. 

 It is astonishing that it should have run so fast ; as he afterwards saw that the 

 river of lava, in the Arrio di Cavallo, was 6o and 70 feet deep, and in some 

 places near 2 miles broad. When his Sicilian majesty quitted Portici, the noise 

 was greatly increased, and the confusion of the air from the explosions was so 

 violent, that, in the king's palace, doors and windows were forced open, and even 

 one door there, which was locked, was burst open. At Naples, the same night, 

 many windows and doors flew open. Besides the explosions, which were very fre- 

 quent, there was a continued subterraneous and violent rumbling noise, which 

 lasted this night about 5 hours. Sir W. imagined that this extraordinary noise 

 might be owing to the lava in the bowels of the mountain having met with a de- 

 position of rain water, and that the conflict between the fire and the water may, 

 in some measure, account for so extraordinary a crackling and hissing noise. 

 In the great eruption of Mount Vesuvius in l663, it is well attested, that several 

 towns, among which Portici and Torre del Greco, were destroyed by a torrent of 

 boiling water having burst out of the mountain with the lava, by which thou- 

 sands of lives were lost. About 4 years ago, Mount Etna in Sicily threw up 

 hot water also, during an eruption. 



Tuesday the 20th, it was impossible to judge of the situation of Vesuvius, on 

 account of the smoke and ashes which covered it entirely, and spread over 

 Naples also, the sun appearing as through a thick London fog, or a smoked 

 glass ; small ashes fell all this day at Naples. The lavas on both sides of the 



