Chap. 85.] 
PEODiaiES OF THE EARTH. 
115 
difference in the nature of the motions \ where various mo- 
tions are experienced. It is the safest when it vibrates and 
causes a creaking in the building, and where it swells and 
rises upwards, and settles with an alternate motion. It is 
also harmless when the buildings coming together butt 
against each other in opposite directions, for the motions 
counteract each other. A movement like the rolling of waves 
is dangerous, or when the motion is impelled in one direction. 
The tremors cease when the vapour bursts out^ ; but if 
they do not soon cease, thej continue for forty days ; gene- 
rally, indeed, for a longer time : some have lasted even for 
one or two years. 
CHAP. 85. (83.) — PEODIOIES OE THE EAETH WHICH HATE 
OCCUREED OKCE ONLY. 
A great prodigy of the earth, which never happened more 
than once, I have found mentioned in thebooks of the Etruscan 
ceremonies, as having taken place in the district of Mutina, 
during the consulship of Lucius Martins and Sextus Julius^. 
Two mountains rushed together, falling upon each other 
with a very loud crash, and then receding ; while in the day- 
time flame and smoke issued from them ; a great crowd of 
IRoman knights, and families of people, and travellers on the 
^milian way, being spectators of it. All the farm-houses 
were thrown down by the shock, and a great number of 
animals that were in them were killed ; it was in the year 
before the Social war ; and I am in doubt whether this event 
or the civil commotions were more fatal to the territory of 
Italy. The prodigy which happened in our own age was no 
less wonderful ; in the last year of the emperor Nero'*, as I 
have related in my history of his times ^, when certain fields 
and olive grounds in the district of Marrucinum, belonging 
to Yectius Marcellus, a Roman knight, the steward of Nero-, 
^ These remarks upon the different kinds of shocks are probably taken 
from Aristotle, Meteor, ii. 8. 
- This observation is also in Aristotle, ii. 8. 
3 In the year of the city 663 ; a.c. 90. 
^ In the year of the city 821 ; a.d. 68. 
^ The continuation of Aufidins Bassus' •history ; our author refers 
to it in the first book. 
i2 
