Cyrus Harding thought, not without reason, that the overplus of the lake must overflow on this side.  The excess of water furnished by the Red Creek must also escape by some channel or other.  Now the engineer had not yet found this channel on any part of the shore already explored, that is to say, from the mouth of the stream on the west of Prospect Heights.

The engineer now proposed to his companions to climb the slope, and to return to the Chimneys by the heights, while exploring the northern and eastern shores of the lake.  The proposal was accepted, and in a few minutes Herbert and Neb were on the upper plateau.  Cyrus Harding, Gideon Spilett, and Pencroft followed with more sedate steps.

The beautiful sheet of water glittered through the trees under the rays of the sun.  In this direction the country was charming.  The eye feasted on the groups of trees.  Some old trunks, bent with age, showed black against the verdant grass which covered the ground.  Crowds of brilliant cockatoos screamed among the branches, moving prisms, hopping from one bough to another.

The settlers instead of going directly to the north bank of the lake, made a circuit round the edge of the plateau, so as to join the mouth of the creek on its left bank.  It was a detour of more than a mile and a half.  Walking was easy, for the trees widely spread, left a considerable space between them.  The fertile zone evidently stopped at this point, and vegetation would be less vigorous in the part between the course of the Creek and the Mercy.

Cyrus Harding and his companions walked over this new ground with great care.  Bows, arrows, and sticks with sharp iron points were their only weapons.  However, no wild beast showed itself, and it was probable that these animals frequented rather the thick forests in the south; but the settlers had the disagreeable surprise of seeing Top stop before a snake of great size, measuring from fourteen to fifteen feet in length.  Neb killed it by a blow from his stick.  Cyrus Harding examined the reptile, and declared it not venomous, for it belonged to that species of diamond serpents which the natives of New South Wales rear.  But it was possible that others existed whose bite was mortal such as the deaf vipers with forked tails, which rise up under the feet, or those winged snakes, furnished with two ears, which enable them to proceed with great rapidity.  Top, the first moment of surprise over, began a reptile chase with such eagerness, that they feared for his safety.  His master called him back directly.

The mouth of the Red Creek, at the place where it entered into the lake, was soon reached.  The explorers recognized on the opposite shore the point which they had visited on their descent from Mount Franklin.  Cyrus Harding ascertained that the flow of water into it from the creek was considerable.  Nature must therefore have provided some place for the escape of the overplus.  This doubtless formed a fall, which, if it could be discovered, would be of great use.