a charge of cavalry. Once or twice
before, since they had taken up their abode on the island, the girls
had caught a faint, far-off echo of just such a sound. To-day it
sounded much nearer.

"What was that?" demanded Phil quickly, raising her hand.

"It sounds like a cavalry charge," returned Madge, trying to smile,
though feeling vaguely alarmed.

The noise swept nearer, like the rush of the wind. Then it stopped as
abruptly as it had begun.

Neither girl offered to stir from under the tree where they had halted
in order to go on with their pilgrimage. The mystery of the noise that
they had just heard made their adventure seem far more perilous. What
on earth was it? What did it mean?

The atmosphere was clear. The travelers guessed they must have come to
about the center of the island. It was a broad, open plateau, covered
with grasses and wild flowers. Neither of the girls thought of how
curious it was to find the grass cropped as close to its roots as
though it had been cut down by a mowing machine.

Phil was walking slowly ahead. There was an opening through a double
avenue of trees, and Phil wanted to find out whether they could get
through the woods by this cut. For the moment Madge's back was turned
to Phil. She was reaching up for a particularly splendid bunch of
Virginia creeper that clung to a branch over her head.

Like a roll of thunder from a clear sky, or the rumble of heavy
artillery, came the noise that they had heard before. It was indeed the
rushing of many feet and it was coming nearer.

Phil ran toward a low-branched tree. "Climb the tree, Madge!" she
cried.

But Madge only stared intently ahead of her.

Some distance ahead a single dark object made its appearance. It walked
on four feet, had a thick, shaggy mane, and its long black tail swept
the ground in a proud arch. Its coat was rough----

Madge clapped her hands. To Phil's horror her chum started to run
forward, instead of taking refuge in a tree.

"It's only a strange-looking horse!" she cried in relief. Madge had
never in her life seen a horse of which she felt afraid.

At almost the same instant, back of the single horse, which was plainly
the leader of a drove, appeared another, then a dozen, twenty or thirty
more horses. The entire drove was galloping recklessly ahead. It was
the noise of their charge that had indeed sounded like a rush of
cavalry.

The leader of the horses caught sight of Madge. What must it have
thou