Book 10
1.100
or again may be caused by exhalations of moisture risingLucr. vi. 519. from suitable places through the air, while a more violent inundation is due to certain accumulations suitable for such discharge. Thunder may be due to the rolling of wind in the hollow parts of the clouds, as it is sometimes imprisoned in vessels which we use; or to the roaring of fire in them when blown by a wind,Cf. Lucr. vi. 271-284. or to the rending and disruption of clouds, or to the friction and splitting up of clouds when they have become as firm as ice.
