By the light of the fire he cut two little flat rulers, which he joined together at one end so as to form a pair of compasses, whose legs could separate or come together.

The fastening was fixed with a strong acacia thorn which was found in the wood pile.

This instrument finished, the engineer returned to the beach, but as it was necessary to take the height of the pole from above a clear horizon, that is, a sea horizon, and as Claw Cape hid the southern horizon, he was obliged to look for a more suitable station.

The best would evidently have been the shore exposed directly to the south; but the Mercy would have to be crossed, and that was a difficulty.

Harding resolved, in consequence, to make his observation from Prospect Heights, taking into consideration its height above the level of the sea--a height which he intended to calculate next day by a simple process of elementary geometry.
The settlers, therefore, went to the plateau, ascending the left bank of the Mercy, and placed themselves on the edge which looked northwest and southeast, that is, above the curiously-shaped rocks which bordered the river.
This part of the plateau commanded the heights of the left bank, which sloped away to the extremity of Claw Cape, and to the southern side of the island.