ittle deeper to make it impracticable for animals, on all the eastern
border by the sea itself, from the mouth of the aforesaid creek to the
mouth of the Mercy.

Lastly, on the south, from the mouth to the turn of the Mercy where the
bridge was to be established.

The western border of the plateau now remained between the turn of the
river and the southern angle of the lake, a distance of about a mile,
which was open to all comers. But nothing could be easier than to dig a
broad deep ditch, which could be filled from the lake, and the overflow
of which would throw itself by a rapid fall into the bed of the Mercy.
The level of the lake would, no doubt, be somewhat lowered by this fresh
discharge of its waters, but Cyrus Harding had ascertained that the
volume of water in the Red Creek was considerable enough to allow of the
execution of this project.

"So then," added the engineer, "Prospect Heights will become a regular
island, being surrounded with water on all sides, and only communicating
with the rest of our domain by the bridge which we are about to throw
across the Mercy, the two little bridges already established above and
below the fall; and, lastly, two other little bridges which must be
constructed, one over the canal which I propose to dig, the other across
to the left bank of the Mercy. Now, if these bridges can be raised at
will, Prospect Heights will be guarded from any surprise."

The bridge was the most urgent work. Trees were selected, cut down,
stripped of their branches, and cut into beams, joists, and planks. The
end of the bridge which rested on the right bank of the Mercy was to be
firm, but the other end on the left bank was to be movable, so that it
might be raised by means of a counterpoise, as some canal bridges are
managed.

This was certainly a considerable work, and though it was skillfully
conducted, it took some time, for the Mercy at this place was eighty
feet wide. It was therefore necessary to fix piles in the bed of
the river so as to sustain the floor of the bridge and establish a
pile-driver to act on the tops of these piles, which would thus form two
arches and allow the bridge to support heavy loads.

Happily there was no want of tools with which to shape the wood, nor
of iron-work to make it firm, nor of the ingenuity of a man who had a
marvelous knowledge of the work, nor lastly, the zeal of his companions,
who in seven months had necessarily acquired great skill in the use