Suppose, that during our absence, Master Jup takes it into his head
to draw up the ladder which he so politely returned to us yesterday?"

"Let us tie its lower end down firmly," replied Cyrus Harding.

This was done by means of two stakes securely fixed in the sand. Then
the settlers, ascending the left bank of the Mercy, soon arrived at
the angle formed by the river.

There they halted, in order to ascertain if the bridge could be thrown
across. The place appeared suitable.

In fact, from this spot, to Port Balloon, discovered the day before on
the southern coast, there was only a distance of three miles and a
half, and from the bridge to the Port, it would be easy to make a good
cart-road which would render the communication between Granite House
and the south of the island extremely easy.

Cyrus Harding now imparted to his companions a scheme for completely
isolating Prospect Heights so as to shelter it from the attacks both
of quadrupeds and quadrumana. In this way, Granite House, the
Chimneys, the poultry-yard, and all the upper part of the plateau
which was to be used for cultivation, would be protected against the
depredations of animals. Nothing could be easier than to execute this
project, and this is how the engineer intended to set to work.

The plateau was already defended on three sides by watercourses,
either artificial or natural. On the north-west, by the shores of Lake
Grant, from the entrance of the passage to the breach made in the
banks of the lake for the escape of the water.

On the north, from this breach to the sea, by the new watercourse
which had hollowed out a bed for itself across the plateau and shore,
above and below the fall, and it would be enough to dig the bed of
this creek a little 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 wa