Several days passed, during which the drizzle scarcely ceased for a moment.  But during all this time the young woman was not idle, so far as her new interests were concerned.  She had asked questions, inquiring the names of things and their uses until she knew them intimately.  The ropes and stays, from a mass of complex, meaningless cordage, had resolved themselves into individual units, each of which had its use and its purpose; the compass was no longer a mystery, and, during a lull in the drizzle, when the sun had come out on the fifth day, Harriet was permitted to take an observation with the sextant, the instrument with which mariners take sights to determine their positions at sea.

Harriet was instructed to catch the sun at its zenith, which she did, noting the figures on the scale of the sextant and from which, under the instruction of the captain, she figured out the latitude of the sloop.  He allowed her to do all the figuring herself.  The result was startling.  The skipper took her calculations, studied them, frowned, then permitted his face to expand into a wrinkled grin.

“Young lady, did you think this was Noah’s Ark!” he demanded.

“No, sir.  Wh—­y?”

“Because according to your figures the ‘Sister Sue’ is at this minute located on a line with Mt.  Washington, off yonder in the White Range.”

Harriet flushed to the roots of her hair as her companions shouted gleefully.  At last Harriet Burrell had found something that she could not do.  But the captain quickly informed them that to be able to take observations accurately, and then figure them out, required long and close application.  Some mariners never were really good at theoretical navigation.  Nor had Harriet, as yet, mastered the principles of trigonometry, which branch of mathematics underlies navigation.

On the following morning the sun came out, and by the time the camp was awake the mainsails and jibs had been put out to dry.  They were permitted to swing free all day long and by nightfall were dry and white, ready for the next sail.  Captain Billy had promised them a long sail, though not having told them where.  That evening he consulted with the Chief Guardian in her tent, with the result that the Meadow-Brook Girls, Miss Elting and five of their companions were told to prepare themselves for an early departure on the following morning, provided the day were fair.

The girls were delighted, especially Harriet, who looked forward to putting into actual practice the theories that she had learned.  A full day’s provisions were put aboard, for these long sails could not be made on schedule time in every instance.  An early breakfast was eaten by those who were to go on the sail, after which, bidding good-bye to their companions who remained behind, the sailing party set out for the beach, where Captain Billy was awaiting them with the small boat.  The passengers were put aboard in two loads, Harriet and Crazy Jane in the first boat.  The two girls set the jibs, which they had in place by the time the skipper returned with the others of the sailing party.  They then hoisted the mainsail, and were under way a very few minutes after the party was snugly aboard.  The “Sister Sue” sailed out of the bay to the accompaniment of fluttering handkerchiefs from the shore and shrill cries of good-bye.