A sudden gust of rain is almost sure to succeed a violent detonation
immediately overhead. Mr. Birt, the meteorologist, asks: Is this rain a
_cause_ or _consequence_ of the electric discharge? To this he replies:
In the sudden agglomeration of many minute and feebly electrified
globules into one rain-drop, the quantity of electricity is
increased in a greater proportion than the surface over which
(according to the laws of electric distribution) it is spread. By
tension, therefore, it is increased, and may attain the point when
it is capable of separating from the _drop_ to seek the surface of
the _cloud_, or of the newly-formed descending body of rain, which,
under such circumstances, may be regarded as a conducting medium.
Arrived at this surface, the tension, for the same reason, becomes
enormous, and a flash escapes. This theory Mr. Birt has confirmed
by observation of rain in thunderstorms.