If they are, as is claimed by some, for vents to the interior molten
condition, why do they become extinct, so many of them, and almost
invariably become lakes inside their craters?
With the whole center of the Earth a molten mass, there ought to be
fire enough to keep them going incessantly. Where does the water come
from to keep up a constant outpour of steam and vapor in locations
where it seldom rains?
It would seem as if the small amount of rain or snow that fell would
get pretty well dried out before it arrived at a point to create an
eruption by contact with melted rock, or that such a quantity could
keep up steam in such an immense cauldron. There is no reason to
presume that a drop of rain water ever enters a volcanic crater, except
what may fall into its open mouth, which will be impossible.
Have Volcanoes any specific use in Earth economics? Do they tend to
open up water courses from the interior and by their upheavals on the
continents and islands of the Earth create natural elevated reservoirs
from which the lower regions of Earth can be irrigated? Do they not
send out certain gases to mingle in the atmosphere, producing favorable
results in vegetation and animal life? Are not the vicinities of
volcanoes noted for the fine fruits and wines in latitudes in which
they grow?