"I'll come back here in the morning and have a look," she promised herself. "Won't tell the girls; they've troubles enough."

She made her way back to the yacht and was soon in her berth fast asleep.

It was with considerable amus.e.m.e.nt that she retraced her steps next morning. There could not, she told herself, be a wireless station of any kind on that island. A wireless station called for a home for the operators and there was no such home. She and Marian had made sure of that.

"But then what was it?" she asked herself, "What could it have been?"

She climbed the tree, this time up to its very top, then, turning, shaded her eyes to gaze away the length of the island.

"Just as I thought," she murmured. "Nothing. Just nothing at all."

It was true. There could be no wireless tower. If there had been she could have seen it. What was more, there certainly was no house on the island. Had there been, she could not have failed to detect its roof from her point of vantage.

There was no house and no wireless station, yet, as she looked her lips parted in an exclamation of surprise.

She was witnessing strange things. Toward the other end of the island something was moving in and out among the drifting ice-cakes. This, she made out presently, by the flash of a paddle, was some sort of a boat.

"And it is," she breathed. "No--no it can't be! Yes, it is, it's an Eskimo kiak!"

At once she thought of the Negontisks. Could it be possible that they had stumbled upon a secret home of some of these people?

As if in answer to her question, the strange manipulator of this queer craft drew the kiak on sh.o.r.e, then, skipping hurriedly along the beach and up a sandy ridge, suddenly put two hands on something and the next instant dropped straight down and out of sight.

Florence caught her breath sharply. She clutched the fir boughs in the fear that she would fall.

Then, realizing that she might be plainly seen if anyone chanced to look her way, she began hastily to descend.

"He might come out of his igloo and see me," she told herself.

That the thing the person had entered was an igloo she had no reason to doubt. Igloos go with kiaks and are built beneath the earth.

"But," she said suddenly, "the other girls will know a great deal more about those things than I do. I must tell them at once. We will hold a council of war."

CHAPTER XV THE ISLAND'S SECRET

Twenty-four hours after Florence's mysterious discovery, the cabin of the O Moo was pervaded by a quiet and studious atmosphere. Lucile, who was quite herself again, was mastering the contents of a book devoted to the study of the technique of short story writing. Florence was delving into the mysteries of the working of the human mind. Marian was doing a still life study in charcoal.

One might conclude that by some hosts of good fairies the yacht had been spirited back to its place on the dry dock. This was not, however, the case. The O Moo was still standing in the little stream on the sandy island. Its position had been altered a trifle. It had been poled out into midstream and there anch.o.r.ed. This precaution the girls had felt was necessary. In case the Negontisks attempted to board the yacht it would give those on board a slight advantage. It is difficult to board a yacht from kiaks.

That the strange persons who lived in holes beneath the sand dunes were these wild natives they did not doubt. "For," Marian had reasoned, "who else in all the wide world would live in such a manner?"

"Yes, but," Florence had argued, "how did they ever get to the sh.o.r.es of Lake Michigan anyway?"

The question could not be answered. The fact remained that there were people living beneath the ground on this island and that the girls were afraid of them, so much afraid that they were not willing, voluntarily, to expose themselves to view.

This was why they were remaining aboard the O Moo and studying rather than attempting to catch fish. "Might as well make the best of our time,"

Florence had reasoned. To this the others had agreed but when she went on to say that she somehow felt that they would be back at the university for final exams, they shook their heads.

The food supply was growing lower with every meal. Six cans of the unknown fruits and vegetables had been opened and with all the perversity of unknown quant.i.ties had turned out to be fruit, pleasing but not nourishing.

"There's some comfort in knowing that there are other people on the island, at that," Lucile had argued. "They've probably got a supply of food and, rather than starve, we can cast ourselves upon their mercy."

"How many of them do you suppose there are?" Marian suddenly looked up from her book to ask.

"Only saw one," answered Florence, "but then of course there are others."

"Strange we didn't see any tracks when we went the rounds of the island."

"Snowed the night before."

"But people usually have things outside their igloos; sleds, boats and hunting gear."

"Not when they're in hiding. There might be fifty or a hundred of them.

Nothing about an igloo shows unless you chance to walk right up to the entrance or the skylight. And we didn't. We--"

She broke off abruptly as Lucile whispered. "What was that?"

She had hardly asked the question when the sound came again--a loud trill. It was followed this time by a musical:

"Who-hoo!"

"I never heard a native make a sound like that," exclaimed Lucile, springing to her feet.

"Nor I," said Marian.

"Sounds like a girl."

Throwing caution to the wind the three of them rushed for the door.

On reaching the deck, they saw, standing on sh.o.r.e, a very short, plump person with a smiling face. Though the face was unmistakably that of a white girl, she was dressed from head to toe in the fur garments of an Eskimo.

"h.e.l.lo there," she shouted, "Let down the gang plank. I want to come aboard."

"Haven't any," laughed Florence. "Wait a minute. You climb out on that old tree. We'll pole the yacht around beneath it, then you can drop down on deck."

"What a spiffy little cabin," exclaimed the stranger as she entered the door and prepared to draw her fur parka off over her head. "I wasn't expecting company. When did you arrive?"

"Came in with the ice-floe," smiled Marian.

"Are--are you a captive?" asked Lucile suddenly. "And--and do they make you live with them?"

"Captive? Live with whom?" the girl's eyes were big with wonder.

"The Negontisks."