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DUSTY
RAIN­
STORMS
and
SUNSETS
by W. C. Dumas
DUST has been for so long the
enemy of the house-wife, the
cause of municipal legislation
and the bearer of disease,
that it is seldom thought of as
being a beneficial as well as an indispensable
factor in life on the earth. This
despised substance gives us the azure
vaults of heaven, the crimson and golden
glories of sunrise and sunset, the beauty
of the summer clouds, and the rain itself.
A closer examination of the phenomena
due to dust will convince us that
it is absolutely necessary to us even in
our daily lives.
What we call dust has been formed
primarily in all cases by abrasion or friction,
be the origin vegetable, animal, volcanic,
or cosmic. It has been distributed
through several agencies. Dust of course
exists everywhere even up to enormous
heights in the air, and the minutest particles
are floating as high as twenty-five
lo thirty miles. These were carried to
such enormous heights by the atmospheric
currents which keep the particles
from settling. Volcanoes are the cause
of large quantities of this dust which fill
vast regions of atmosphere.
In one eruption of Cotopaxi, dust and
ashes to the*estimated weight of two
million tons were thrown into the air.
The vast volcanic forces completely shatter
these ejected materials into minute
particles which are carried by winds and
currents of air to enormous distances.
The eruption of Krakatoa in the Indian
Ocean filled the higher stretches of
atmosphere with immense quantities of
dust. For a long time afterwards, this
dust caused brilliant sunsets in different
parts of the world.
This atmospheric dust is of microscopic
dimensions, probably less than one
one-thousandth of a millimeter, or one
twenty-five thousandth of an inch in
average diameter. The scientist, Arrhenius.
has given us an interesting computation
in regard to this cosmic dust. He
imagines each cubic kilometer of space
out to the distance of the nearest fixed
star to contain only one hundred particles
evenly distributed. Then at this
distance, the light of the stars would be
cut off completely from our view by dust
particles!
The presence of dust up to immense
heights can be demonstrated by the use
of 'gelatine plates sent up on kites or
balloons. The exposed surfaces of these
plates catch and hold the minute particles
which afterwards can be identified by
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