Fig. 4. Diagram of Their Trip
On the third day, however, the ground became more level and less broken, the sun appeared, and they felt happy at the thought of getting back again.
Thus far in their wanderings they had kept their reckonings, as well as they could without instruments, and that evening the chart was again consulted, as usual. The drawing (Figure 4) shows how it looked with the course of their journey.
When they started from the Cataract home at nine o'clock in the morning, they made an observation of the sun, using a vertical pole so as to get the exact direction of the falling shadow. A distant object was then selected, a prominent tree, as far off as possible. The Professor had prepared an adjustable bevel square, which was simply two legs hinged together at one end, by means of a set screw, like a compass.
