236 THE POPULAR SCIENCE MONTHLY. 



kind we are pursuing. Now no fragments of lava, not a vestige of 

 it, are to be found there, nor any trace of injury caused by lava. On 

 the contrary, on examining the perpendicular surfaces surrounding 

 this four-sided space, every thing is ashes ; 30 or 36 feet deep of 

 ashes ; only at the upper part a few bits of coal are seen, ejections 

 from the volcano, layers corresponding with the modern eruptions, and 

 separated by layers of vegetable earth which have had time to be de- 

 posited between the several eruptions. Look at the fragments of stuff 

 dug out of one of those caveras examine them you will still find 

 nothing in them but ashes, bi'oken up by the pick as readily as clay or 

 pumice. 



But it may be asked, How could ashes which are light as dust, and 

 with no coherence, gain hardness enough to take durable impressions, 

 to form supporting arches, and to bear so delusive a look of solidity as 

 to be taken for lava ? The ready answer is found in the example of 

 Pompeii, and the casts found in the cellars of Diomed's house ; but 

 similar and even more striking cases may help us to understand such 

 power of adhesion. In the valleys of Monte Cavo there are ledges of 

 peperino, formed by the filling up of volcanic ashes mingled with wa- 

 ter. This compost grew so dense that the Romans used it for building- 

 material. The Catacombs of Rome, which are nothing else than a vol- 

 canic tufa, that is, sand and pulverized fragments, compressed by time 

 and their own weight, are in like manner friable, easy to cut, easier to 

 rub down, and yet galleries are dug in them, arches, ceilings, stairways, 

 numberless tombs, and as many as five stories of excavations, beneath 

 each other ! Nor must it be forgotten that pumice, which furnishes 

 so excellent a water-lime, was taken originally from Pozzuola, near 

 Vesuvius, and is nothing more than a ferruginous clay, once subjected 

 to high volcanic temperature, and ejected in a shower of ashes. I re- 

 call, too, the great altar at Olympia, described by the traveller Pausa- 

 nias, which was formed entirely from the ashes of the victims sacrificed 

 to Jupiter. After every sacrifice the priests moistened the ashes with 

 water from the Alpheus, smeared the altar with them, and so enlarged 

 it gradually until, during ten centuries, the structure gained 125 feet in 

 circuit, and 22 in height. Indeed, any one who has seen water flung 

 into a fireplace may judge of the toughness of ashes when mixed with 

 liquids ; much more must the volcanic ashes of the Roman Carnpagna, 

 of Naples and Santorin be suited for making cements. 



For the rest, should this explanation only half satisfy the reader, 

 there are the facts, and not to be denied. I defy any careful observer, 

 examining the parts of Herculaneum hitherto brought to light, to dis- 

 cover any thing else in them than ashes. It may be that, on the surface 

 of the existing soil of Portici, which has been raised at least 60 feet, 

 marks of lava-flows are traceable which belong to modern eruptions, 

 especially toward Resina. Neither can I affirm that, in some unex- 

 plored quarter of Herculaneum, the presence of lava may not some day 



