me more stable, but even now there is scarcely a day when
the instruments called seismographs do not record earthquake shocks in
some part of the earth; and the outbreaks of Vesuvius and AEtna, the
constant boiling of lava in the craters of the Hawaiian Islands and
other volcanic centres, prove that even now the earth's crust is very
thin and unstable. The further back in time we go, the thinner was the
crust, the more frequent the outbursts of volcanic activity, the more
readily did wrinkles form.

The shores of New Jersey and of Greenland are gradually sinking, and the
sea coming up over the land. Certain parts of the world are gradually
rising out of the sea. In earlier times the rising or the sinking of
land over large areas happened much more frequently than now.

WHAT IS THE EARTH MADE OF?

"Baking day" is a great institution in the comfortable farm life of the
American people. The big range oven is not allowed to grow cold until
rows of pies adorn the pantry shelves, and cakes, tarts, and generous
loaves of bread are added to the store. Cookies, perhaps, and a big pan
full of crisp, brown doughnuts often crown the day's work. No gallery of
art treasures will ever charm the grown-up boys and girls as those
pantry shelves charmed the bright-eyed, hungry children, who were
allowed to survey the treasure-house, and sample its good things while
they were still warm.

You could count a dozen different kinds of cakes and pies, rolls and
cookies on those pantry shelves, yet several of them were made out of
the same dough. Instead of a loaf of bread, mother could make two or
three kinds of coffee cake, or cinnamon rolls, or currant buns, or
Parker-House rolls. Even the pastry, which made the pies and tarts, was
not so different from the bread dough, for each was made of flour, and
contained, besides the salt, "shortening," which was butter or lard.
Sugar was used in everything, from the bread, which had a
table-spoonful, to the cookies, which were finished with a sifting of
sugar on top.

How much of the food we eat is made of a very few staple
foodstuffs,--starch, sugar, fats! So in the wonderful earth and all that
grows out of it and lives upon it. Only seventy different elements have
been discovered, counting, besides the earth, the water and the air, and
even the strange wandering bodies, called meteorites, that fall upon the
earth out of the sky. Like the flour in the different cakes and pies,
the eleme