e moisture it will hold. This,
taken with the fact that cold currents are encountered high up,
sufficiently answers the question.

It is interesting to know that the processes of nature are
interdependent. It is not enough that we have the evaporation of
moisture that will ascend into the higher regions of the air and there
be condensed into cloud and possibly rain, but we must have the means
for distributing these conditions over a large area, and for this
purpose we have the phenomenon of wind. Why the winds blow can be
accounted for to a certain extent,--we might say to a large extent,--but
there yet remain many unsolved problems relating to wind and weather. Of
the phenomena of wind we will speak more fully in a future chapter.

CHAPTER IX.

CLOUD FORMATION--CONTINUED.

As water in its condensed state is 815 times heavier than air, the
question naturally comes to one why it does not immediately fall to the
earth when it condenses. There are at least two and probably more stages
of condensation. Investigators into the phenomenon of cloud formation
claim to have ascertained that the first effect of condensation is to
form little globes of moisture that are hollow, like a bubble, with very
thin walls. Everyone has recognized the ease with which a soap bubble
will float in the air, and yet it is simply a film of moisture. These
little balloons, so to speak, are called spherules. It is undoubtedly
the case that mingled with these little bubbles of moisture there are
fine particles of solid water hanging on and carried along with them.
Undoubtedly this is true; at least just before the final act of
condensation takes place; and when the little hollow spherules collapse
they are gathered together in drops of water larger or smaller according
to the rapidity of condensation. There is probably another power at
work to prevent the too ready precipitation of moisture when condensed,
and that is the wind. A cloud never stands still, although in some cases
it may appear to do so. If we take a stone in our hand and allow it to
drop without applying any force to it, it will fall directly to the
ground. But if we give it an impetus in a horizontal direction it will
travel some distance before striking the ground. If we could give the
same impetus to a body as light as a globule of water-dust it would
probably travel indefinitely without falling. Dust that would settle
directly to the ground from an elevation in still ai