THEIR P11ES0MEN.V. 
165 
has journeyed through Spanish America, should have chief! v 
nxed his attention on volcanoes and earthquakes. Each part 
ot the globe is an object of particular study; and when we 
cannot hope to penetrate the causes of natural phenomena 
we ought at least to endeavour to discover their laws, and 
distinguish, by the comparison of numerous facts, that which 
is permanent and uniform from that which is variable and 
accidental. 
The great earthquakes, which interrupt the long series of 
slight shocks, appear to have no regular periods at Cumana 
they have taken place at intervals of eighty, a hundred 
and sometmies. less than thirty years ; while oil the coasts 
ot Peru, tor instance at Lima, a certain regularity has 
marked the periods of the total destruction of the city. 
Ihe .belief of the inhabitants in the existence of this uni- 
tormitj has a happy influence on public tranquillity, and the 
encouragement of industry. It is generally admitted, that 
it requires a sufficiently long space of time for the sams 
causes to act with the same energy ; but this reasoning is 
just only inasmuch as the shocks are considered as a local 
phenomenon ; and a particidar focus, under each point of 
the globe exposed to those great catastrophes, is admitted. 
V\ henever new edifices are raised on the ruins of the old 
w-e hear from those who refuse to build, that the destruction 
ot Lisbon on the first day of November, 1755, was soon 
tollow ed by a second, and not less fatal convulsion, on the 
dlst of March, 1761. 
It is a very ancient opinion* and one that is commonly 
received at Cumana, Acapulco, and Lima, that a perceptible 
connection exists between earthquakes and the state of the 
atmosphere that precedes those phenomena. But from the 
great number of earthquakes which I have witnessed to the 
north and south of the equator ; on the continent, and on the 
T „‘ e COa ?n\ ; al,d at 2500 toises height ; it appears to 
ne that, the oscillations are generally very independent of 
he previous state of the atmosphere. This opinion is enter- 
tained by a number of intelligent residents of the Spanish 
coioines, whose experience extends, if not over a greater 
space ot the globe, at least over a greater number of years, 
tib ' a ’ (ed ' Duva1, tom - ■ p- ?98 )- Senecj > Nat. 
