They sailed for two hours, then the sloop returned to the bay, where most of the girls were put ashore and another lot taken aboard.  The Meadow-Brook Girls and Mrs. Livingston remained on board.  Harriet, during the time the captain was engaged in assisting his passengers over the side, where they were rowed ashore by Jane and Hazel, looked over the “Sister Sue” with more care than she had done before.  There was nothing that she could discover that looked like a wireless apparatus.  However, at the forward end of the cabin she discovered a small door let into the paneling.  This door was locked.  She asked the captain to what it opened.

“That’s the chain locker, where we stow things,” he answered gruffly.

The girl then began calculating on how much space there was under the floor of the cabin.  She decided that there must be at least three feet of hull under there, but the flooring was covered with carpet that extended under the lockers and seats at the side, so that she was unable to determine whether or not the floor could be readily taken up.  Altogether, her discoveries did not amount to very much.  She was obliged to confess as much to herself.  As for Tommy, that young woman had conducted herself admirably during the sail, proving that she was discreet and fully as keen as was Harriet Burrell; and, though Tommy said very little on the subject uppermost in the minds of the two girls, the little girl was constantly on the alert.

In the joy of sailing they forgot their noon meal.  Nor were they reminded of it when Captain Bill, giving Harriet the wheel, made himself a cup of black coffee over an oil stove and drank it, eating several slices of dry bread.  Having finished his luncheon, he pointed to the compass, asking Harriet if she knew anything about it.  She said she did not.

[Illustration:  Harriet Took the Wheel.]

“If you are going to be a sailor, you must learn to read the compass,” he said.  “In the first place, you must learn to ‘box the compass.’  I’ll show you.”

“Are you looking for the boxth?” questioned Tommy, observing the skipper searching for something in a locker under the stern seat.

“Box?  No,” he grunted.  “We don’t use that kind of a box in boxing the compass.  By boxing the compass we mean reading the points of it.”  He produced a long, stiff wire, with which he pointed to the compass card.  “A mariner’s compass is divided into thirty-two points,” he informed Harriet.  “In the first place, there are four cardinal points, North, East, South and West.  As you will see, by looking at the compass card, it is divided into smaller points which are not named on the card.  I’ll draw you a card to-night with all the points named, then you can learn them.  Until you do, you are not a sailor.  For instance, to read the compass, we begin with North and go on until we have completed the circle of the card, naming each point and sub-division as we go along.  Then you should learn to read it backward as well.  After you have learned to do that I will show you how to lay a course by a chart.”