laces as this
they find it necessary to drive piles, to build the embankment on."

"They must cost a heap of money, then."

"The annual expense even for repairs of dikes in Holland is about three
millions of dollars of our money. Speaking of that very dike of West
Kappel," added the professor, pointing to its long, inclined escarpment,
"it is said if it had been originally built of solid copper, the prime
cost would have been less than the amount which has since been expended
upon it in building, rebuilding, restoring, and repairing it. But the
money spent on dikes is the salvation of Holland. The entire country
would be washed away in a few years, if they were suffered to decay."

"I see there are trees growing on the shore, farther up the river,"
added Paul.

"Those trees are willows; and wherever it is possible for them to
thrive, they encourage their growth for two reasons: first, because the
roots of the trees strengthen the dike; and, secondly, because the
willow twigs are wanted in repairing and securing the embankment. The
foundations of sea-dikes vary from a hundred and twenty to one hundred
and fifty feet in width. The rampart is made of clay, which, as being
impervious to water, forms the entire structure when the material is
available in sufficient quantities. The maximum height of the dikes is
forty feet; but of course they vary in this respect with the elevation
of the land to be protected by them."

"But I should think the mud and clay would be washed away by the beating
of the sea."

"So they are sometimes; and to guard against such an event, which is a
calamity in this country, the dike is covered with a kind of thatch-work
of willow twigs, which has to be renewed every three or four years.
Occasionally the outer surface of the embankment is faced with masonry,
the stone for which has to be brought from Norway."

"A ship there is coming in," interrupted the pilot, pointing to seaward.

She was several miles distant, standing in under all sail. She was
examined with the spy-glasses, and every one was rejoiced to learn that
it was the Young America.

CHAPTER IV.

UP THE SCHELDT TO FLUSHING.

"I am very glad to see the ship again," said Paul to Professor Stoute.

"I supposed she would get in before us, we were detained so long by the
wreck," replied Mr. Stoute.

"Probably she stood off and on during the night, seeking for us," added
Paul, as he again looked through the spy-glass at