[ 602 ] 
drata, may be propagated to very great didances-; 
and even after it has ceafed to be perceived by the 
the fenfes, it may dill difcover itfelf by the appear- 
ances before-mentioned. 
Sect. IV. 
62. All earthquakes derived from the fame fub- 
terraneous fire, mud come to the fame place in the 
fame direction ; and thofe only which are derived 
from different fires, will come from different points 
of the compafs ; but as, in all probability, it feldom 
happens that earthquakes, cauied by different fires, 
affed the fame place, we therefore find in general, 
that they come from the fame quarter : it is not, 
however, to be fuppofed, that this diould always be 
the cafe, for it will, probably, fometimes happen to 
be otherwife : and this is to be expeded in fuch 
places as are fituated in the neighbourhood of feveral 
iubterraneous fires; or where, being fubjed to the 
ihocks of fome local earthquake of final 1 extent, they 
now and then are affeded by an earthquake, produced 
by fome more didant, but much more confiderable 
caufe. Of this lad cafe, we feem to have had fome 
indances in the earthquake of the id of November 
1 75 f , and thofe local ones, before-mentioned, which 
fucceeded it. 
63. As we may reafonably infer from many earth- 
quakes coming to the fame place, from the fame point 
of the compafs, that they are all derived from the 
fame caufe, and that a permanent one ; fo we may 
reafonably infer the fame thing alfo, from their being 
propagated with the fame velocity ; but this argu- 
ment will dill come with the greater force, if it be 
confidered, 
