point of explosion will be greater than that which can be produced
by the most powerful bomb at a distance of a quarter of a mile. In
fact, if the latter can condense vapor a quarter of a mile away,
then anybody can condense vapor in a room by slapping his hands.
Let us, therefore, go to work slapping our hands, and see how long
we must continue before a cloud begins to form.

What we have just said applies principally to the condensation of
invisible vapor. It may be asked whether, if clouds are already
formed, something may not be done to accelerate their condensation
into raindrops large enough to fall to the ground. This also may
be the subject of experiment. Let us stand in the steam escaping
from a kettle and slap our hands. We shall see whether the steam
condenses into drops. I am sure the experiment will be a failure;
and no other conclusion is possible than that the production of
rain by sound or explosions is out of the question.

It must, however, be added that the laws under which the
impalpable particles of water in clouds agglomerate into drops of
rain are not yet understood, and that opinions differ on this
subject. Experiments to decide the question are needed, and it is
to be hoped that the Weather Bureau will undertake them. For
anything we know to the contrary, the agglomeration may be
facilitated by smoke in the air. If it be really true that rains
have been produced by great battles, we may say with confidence
that they were produced by the smoke from the burning powder
rising into the clouds and forming nuclei for the agglomeration
into drops, and not by the mere explosion. If this be the case, if
it was the smoke and not the sound that brought the rain, then by
burning gunpowder and dynamite we are acting much like Charles