TRUE VOLCANOES. 399 



Pompeii), he says, " lies the Mount Vesuios, covered round 

 by the most beautiful farms, except on the summit. This is 

 indeed for the most part pretty smooth, but on the whole un- 

 fruitful, and having an ashy appearance. It exhibits fissured 

 hollows of red-colored rock, as if it were corroded by fire, so 

 that it might be supposed that this place had formerly burned 

 and had gulfs of fire, which, however, had died away when 

 the fuel became consumed." (Strabo, lib. v., page 247, Ca- 

 saub.) This description of the primitive form of Vesuvius 

 indicates neither a cone of cinders nor a crater-like hollow- 

 ing* of the ancient summit, such as, being walled in, could 

 have served Spartacusf and his gladiators for a defensive 

 strong-hold. 



* This description is, therefore, totally at variance with the often- 

 repeated representation of Vesuvius, according to Strabo, given in 

 PoggendoriFs Annalen der Physik, bd. xxxvii., s. 190, tafel 1. It is a 

 very late writer, Dio Cassius, under Septimius Severus, who first speaks, 

 not (as is frequently supposed) of the production of several summits, 

 but of the changes of form which the summits have undergone in the 

 course of time. He records (quite in confirmation of Strabo) that the 

 mountain formerly had every where a flat summit. His words are as 

 follows (lib. Ixvi., cap. 21, ed. Sturz, vol. iv., 1824, p. 240) : "For Vesu- 

 vius is situated by the sea near Naples, and has numerous sources of 

 fire. The whole mountain was formerly of uniform height, and the 

 fire arose from its centre, for at this part only is it in a state of com- 

 bustion. Outwardly, however, the whole of it is still, down to our 

 times, devoid of fire. But while the exterior is always without con- 

 flagration, and the centre is dried up (heated) and converted into cin- 

 ders, the peaks round about it have still their ancient height. But the 

 whole of the igneous part, being consumed by length of time, has be- 

 come hollow by sinking in, so that the whole mountain (if we may com- 

 pare a small thing with a great) resembles an amphitheatre." (Comp. 

 Sturz, vol. vi., Annot. ii., p. 568.) This is a clear description of those 

 mountain masses which, since the year 79, have formed the margins 

 of the crater. The explanation of this passage, by referring it to the 

 Atrio del Cavallo, appears to me erroneous. According to the large 

 and excellent hypsometrical work of that distinguished Olmutz astron- 

 omer, Julius Schmidt, for the year 1855, the Punta Nasone of the 

 Somma is 3771 feet, the Atrio del Cavallo, at the foot of the Punta 

 Nasone, 2661, and the Punta or Rocca del Palo (the highest edge of 

 the crater of Vesuvius to the north, p. 112-116) 3992 feet high. My 

 barometrical measurements of 1822 ( Views of Nature, p. 376-377) gave 

 for the same three points 3747 feet, 2577 feet, and 4022 feet, showing 

 a difference of 24, 84, and 30 feet respectively. The floor of the Atrio 

 del Cavallo has, according to Julius Schmidt {Eruption des Vesuvs im 

 Mai, 1855, p. 95), undergone great alterations of level since the erup- 

 tion of February, 1850. 



t Velleius Paterculus, who died under Tiberius, mentions Vesuvius, 

 it is true, as the mountain which Spartacus occupied with his gladia- 

 tors (ii., 30) ; while Plutarch, in his Biography of Crassus, cap. ii., 

 speaks only of a rocky district having a single narrow entrance. The 



