340 PHYSICAL SCIENCE 



in proof of which he gives various instances, including the late 

 disaster to Pompeii and Herculaneum in a region which had 

 never been known to be shaken before. 



He had received information about the Campanian shock, and 

 the narrative in which he embodies it has the interest of being 

 the most detailed account of an earthquake that has come down 

 to us from antiquity. First of all, as already mentioned, he states 

 that the movement was confined to the district of Campania, no 

 mention being made of its having been felt even so near as Rome. 

 He notices the injury done to Herculaneum and to Naples by 

 the damage of public and private buildings ; bronze statues were 

 split open and some people were driven out of their minds. He 

 records that Campania continued to tremble for some days after 

 the great shock. He had heard that a flock of six hundred sheep 

 was said to have been killed near Pompeii. Accepting the report 

 as true, he sees no reason to suppose that the animals died of 

 fright, but thinks it not unlikely that they were poisoned by the 

 ascent of pestilential vapours from the ground. This conjecture of 

 his receives perhaps some support from the fact that in this volcanic 

 district, after an eruption of Vesuvius, so much carbonic acid gas 

 has been said to escape from the ground as to suffocate hundreds 

 of hares, pheasants, and partridges. But the most vivid experience 

 of the earthquake which he narrates is that of a grave philosophic 

 friend who, when in his bath, saw the tiles of the floor separate 

 from each other, allowing the water to sink through the opened 

 joints, while the next moment, as the pavement closed again, the 

 water was forced out all bubbling. A better illustration of the 

 transit of a wave of shock could not be desired. 



Seneca was prepared to believe that great changes had been 

 wrought by earthquakes on the face of the land. He cites in 

 support of this view some remarkable examples which had 

 occurred within the times of human history, such as the sinking 

 of the towns of Buris and Helice, the disappearance wholly or 

 partially of the island of Atalanta, and the subsidence of Sidon 

 (256). He refers also to various striking features of landscape 

 in different regions which had been popularly assigned to the 

 work of earthquakes, such as the separation of Ossa and Olympus, 

 the disruption of Sicily from the Italian shore, and the severance 

 of Spain from the continent of Africa (263). 



That the phenomena of earthquakes are closely connected 

 with those of volcanoes was the general belief in antiquity, and 

 continued to be accepted up to the middle of last century. It was 

 believed in early days that just as the collision of clouds during 

 storms produces the fire seen in lightning, so during the tempes- 

 tuous agitation of the air within the earth, such heat is generated 



