lve months and mentally calculate what they had accomplished. They
had delved in many of the hidden mysteries of nature and learned the
secrets. Such knowledge had been put to use. They had discovered many
things that gave them pleasure, but in doing so found others that
startled and grieved them. Things inexplainable and impossible to fathom
had crossed their paths on almost every side.

But they were now doing the work of men. The Professor knew how they had
developed, and grown brave and strong. He knew it better than the boys
could realize themselves. What a source of pleasure it must have been to
the kindly faced, gray-haired Professor, as he looked at his charges in
admiration and love. Could anything be more inspiring than the
contemplation of the work he had done?

And now the inevitable charting board was brought out, and the plan
adopted which would enable them to trace the coast line. It was
explained that all sailing was by the points of the compass, and for
this purpose the compass was made to correspond with the regulation
instrument. This is shown in Fig. 23.

[Illustration: _Fig. 23. MARINER'S COMPASS_]

The four cardinal points are north, south, east and west. Exactly midway
between each of the four points are the divisions designated northeast,
southeast, southwest and northwest. Then, again, intermediate, the last
divisions and the cardinal points are other markings which show that the
angles are nearer one of the cardinal points than the other, so that a
course may be marked off, by the compass, which, if followed for a
certain time, and the speed of that period determined, can be traced and
thus marked out on paper so that the outline of the coast can thereby be
laid out.

[Illustration: _The Northern Shore OF WONDER ISLAND. Chart showing Voyage
in "No. 3." Fig. 24._]

The Professor had the charting board before him. "I have marked our
starting point, which is designated as A. It will be remembered that we
marked a course due west, passing the headland three miles from Cataract
River. This is line 1. When we saw the land ahead of us last night, we
changed our course by the compass to northwest, thus making a new line
of travel, which you see is designated as 2. B was the point where the
turn was made."

[Illustration: _Fig. 25. THE CHARTING BOARD_]

"But in what manner did you know how to transfer it to the board?"

"The board has two lines crossing each other at right angles to
correspon