f the arching walls. The vibrations of the water made by the
rower's paddles reecho in sounds like bell notes, and they are
multiplied into harmonies that suggest the chimes in the belfry of a
cathedral.

The walls of various chambers differ from each other according to the
minerals that compose them. Some are creamy white limestone arches, some
are walled with black gypsum, some are hung with great curtains of
stalagmites, solid but suggesting the lightness and grace of folds of
crepe. Under such hangings the floor is built up in stalactites. The
mineral-laden water, the constant drip of which has produced a hanging,
icicle-like stalagmite, has built up the stalactite to meet it.

Probably nothing is more beautiful than the flower-like crystals that
bloom all over the walls of a chamber called "Mary's Bower." The floor,
even, sparkles with jewels that have fallen from the wonderful and
delicate flower clusters built from deposits of the lime-laden water
which goes on building and replacing the bits that fall. "Martha's
Vineyard" is decorated with nodules, like bunches of grapes, that
glisten as if the dew were on them. The white gypsum in some caves makes
the walls look as if they were carved out of snow. Still others have
clear, transparent crystals that make them gleam in the torches' light
as if the walls were encrusted with diamonds.

The cave region of Indiana is also famous. The great Wyandotte Cave in
Crawford County is the most noted of many similar caverns. In some of
the chambers, bats are found clinging to the ceiling, heads downward,
like swarms of bees. The caverns of Luray, in Virginia, are complex and
wonderful in their structure, and famous for the beautiful stalactites
and stalagmites they contain. But there is no cave in this country so
wonderful and so grand in its dimensions as the Mammoth Cave in
Kentucky.

LAND-BUILDING BY RIVERS

Once a year, when the rainy season comes in the mountainous country
south of Egypt, the old Nile floods its banks and spreads its slimy
waters over the land, covering the low plains to the very edge of the
Sahara Desert. The people know it is coming, and are prepared for this
flood. We should think such an overflow of our nearest river a monstrous
calamity, but the Egyptians bless the river which blesses them. They
know that without the Nile's overflow their country would be added to
the Desert of Sahara. In a short time after the overflow, the river
reache