HOW WAS HERCTJLANETJM DESTROYED? 237 



be ascertained ; but, as the present question is only about what we know, 

 that is, the parts of the city which are visible, or examined already, I 

 repeat that not the hundredth part of a square yard of lava can be found 

 at Herculaneum, and that ashes are the only thing there is there. 



The problem to be solved is, how so huge a mass of ashes was ever 

 piled up above the unfortunate city, and, since water played so fearful 

 a part in the catastrophe, whence that enormous quantity of water 

 came. It is clear, in the first place, that these ashes were thrown out 

 by the volcano. Judging from the character of the region, and from 

 the vents formed at the mouth of the crater, the pumice-stones were 

 all hurled toward Pompeii and Stabise, while the ashes drifted toward 

 Herculaneum. Perhaps some allowance must be made for the wind 

 which separated these substances, and the convulsions which ejected 

 them irregularly. Then we must recollect that every very violent 

 eruption is attended by steam produced by the sudden contact of fire 

 with underground sheets of water. The origin of these sheets of water 

 and the effect of their sudden gush into the furnace of eruption have 

 been already explained. These vapors, exceeding the power of calcu- 

 lation in their volume and expansive force, condense at once on contact 

 with the atmosphere ; they cool, and fall again in torrents of rain. If 

 M. Fougire could demonstrate that in 1865, during an eruption by no 

 means extraordinary, there fell on the mountain, in 24 hours, 22,000 

 cubic metres of water, the number must be multiplied by five, or even 

 by ten, to represent that explosion of Vesuvius, A. D. 79, whose fury 

 has never been equalled. Without adopting the hypothesis of mud- 

 discharges from the crater, or citing the example of the volcanoes in 

 Java, which eject mire instead of water-spouts, we may affirm that such 

 volumes of water, mingling with the ashes and pulverized substances 

 thrown out by other vents, suddenly produced a liquid compost, either 

 in the air or on the ground they fell upon. The Neapolitans are fa- 

 miliar with a phenomenon of this sort, occurring more than once, though 

 under limited conditions. They call it " muddy lava," and their use 

 of the substantive would be correct if they always added the adjective, 

 in saying that Herculaneum was buried under lava. Herculaneum, in 

 fact, was buried by muddy lava, or, in simpler terms, by torrents of mud. 



Moreover, these sudden rains, or, rather, deluges, pouring down from 

 the sky at each outburst of steam, swept along all the ashes that had 

 fallen on the slopes of the mountain, and carried them down upon the 

 plain ; an ash-avalanche rolled over Herculaneum. At the same time, 

 the rivers, which ran to the right and left of the city, ceased to flow 

 down to the sea. It has been explained how the coast was elevated, 

 and Pliny's ships kept off, by sudden new shoals preventing access to 

 the port of Resina. The effect of this lifting was to raise the mouths 

 of the two rivers, and throw back their waters on the city, and this 

 overflow added its share of mud, ashes, and vegetable matter. JSTor 

 must we omit the canals filled up, the sewers choked, the aqueducts 



