reaching pronouncements upon the fate
of universes. All these can only be touched lightly, if at all. It is
the chief purpose of this volume to point the way towards the most
modern and the greatest conclusions of Science, and to lay foundations
upon which the reading of a life-time can be laid.

[Illustration: Signature: Edward S. Holden]

UNITED STATES MILITARY ACADEMY, WEST POINT, _January 1, 1902_.

WONDERS OF EARTH, SEA, AND SKY

WHAT THE EARTH'S CRUST IS MADE OF

(FROM THE WORLD'S FOUNDATIONS.)

BY AGNES GIBERNE.

"Stand still and consider the wondrous works of God."

[Illustration]

What is the earth made of--this round earth upon which we human beings
live and move?

A question more easily asked than answered, as regards a very large
portion of it. For the earth is a huge ball nearly eight thousand
miles in diameter, and we who dwell on the outside have no means of
getting down more than a very little way below the surface. So it is
quite impossible for us to speak positively as to the inside of the
earth, and what it is made of. Some people believe the earth's inside
to be hard and solid, while others believe it to be one enormous lake
or furnace of fiery melted rock. But nobody really knows.

This outside crust has been reckoned to be of many different
thicknesses. One man will say it is ten miles thick, and another will
rate it at four hundred miles. So far as regards man's knowledge of
it, gained from mining, from boring, from examination of rocks, and
from reasoning out all that may be learned from these observations, we
shall allow an ample margin if we count the field of geology to extend
some twenty miles downwards from the highest mountain-tops. Beyond
this we find ourselves in a land of darkness and conjecture.

Twenty miles is only one four-hundredth part of the earth's
diameter--a mere thin shell over a massive globe. If the earth were
brought down in size to an ordinary large school globe, a piece of
rough brown paper covering it might well represent the thickness of
this earth-crust, with which the science of geology has to do. And the
whole of the globe, this earth of ours, is but one tiny planet in the
great Solar System. And the centre of that Solar System, the blazing
sun, though equal in size to more than a million earths, is yet
himself but one star amid millions of twinkling stars, scattered
broadcast through the universe. So it would seem at first sight tha