118 Physical Notices of the Bay of Naples, 



authorities, therefore, are the Epistles of Pliny, and the Epi^ 

 tome of'Diori's History by Xiphilin. Preceding this remark- 

 able event, a great earthquake took place in the year 63, of 

 which Seneca gives us a particular account, mentioning that 

 Pompeii was excessively injured, and a part of Herculaneum 

 destroyed ; * and Tacitus expressly says, " Motu terrae cele- 

 bre Campaniae pppidum Pompeii corruit." -f- This event 

 proved only the forerunner of one more tremendous. Pliny 

 relates, J that the ninth day before the Kalends of September, 

 A. D. 79, at the seventh hour, corresponding to the 24th of 

 August, at 1 p. M., a cloud of very unusual shape was observed 

 to rise from Vesuvius, resembling in form a pine-tree, (the stone 

 pine of Italy, with a tall stem and expanded flat head), — a simile 

 which corresponds so exactly with observed appearances, as to 

 be still the usual object of comparison for the cloud which con- 

 stantly ascends previous to an eruption. Its form is clearly 

 owing to a cause which Pliny pretty distinctly points out, that 

 where the force of projection is exactly counterbalanced by the 

 decreased density of the air, combined with the loss of original 

 impetus, the particles for a short time must remain pretty near- 

 ly in equilibrio, and, therefore, liable to be acted upon by the 

 wind, which is very commonly violent at such moments. From 

 the great height of the extended part of the cloud of ashes, 

 that impalpable powder is carried sometimes to immense dis- 

 tances, § and the more ponderable masses are discharged in 

 large quantities near the foot of the mountain. The pheno- 

 menon, therefore, so well described by Pliny, corresponds per- 

 fectly to the precursor of a prodigious " cenere^'^ or shower of 

 ashes. The elder Pliny, resolved to investigate this extraordi- 

 nary phenomenon, was just leaving his house at Misenum to 

 cross the bay to the scene of danger, when he received letters 

 from Rectina, the wife of Nascus, who had a villa on the shore 

 below Vesuvius, entreating his assistance in that awful mo- 

 ment. II He set sail, but was unable to pursue his purpose, 

 not only from the enormous masses which rolled from the 



« Nat, Qjuocd. vi. 11. t Ann. xv. 22. % Epist. vi- 16. 



§ See last Number, p. 206. 



II The reading of this disputed passage I have taken from the famous 

 Aldine edition of 1508. 



