five-thirty I shall expect you in camp. These are my orders." Miss
Sallie turned to Bab and Mollie. "Seriously, children," she explained, "I
think I shall establish military rules. If one of you stays out after
dusk, I believe I shall shut you up in the guard house for twenty-four
hours."

"But where is the guard house please, Miss Sallie?" inquired Mollie
meekly.

Miss Sallie laughed. "In this case the guard house means only the cabin.
The girl who fails to appear when the roll is called in the evening must
remain within the limits of the camp all the following day."

Bab and Mollie left Miss Stuart before the log fire in the living room of
their hut. Miss Sallie, who had a taste for romance in the lives of other
people, was deep in the reading of a new novel. A part of the camping
supplies had been a collection of new books for her.

"Come on, Mollie," cried Bab gayly. "Let's go over in the woods and
gather some pine and cedar branches for our fire this evening." Barbara
walked ahead, pulling a small wagon behind her with all the ardor of a
young boy. "You see," she avowed to Mollie, "I don't have to remember I
am sixteen, or a girl, while we are living in the woods. I can be just as
independent as I like."

The two sisters were deep in their task. The little wagon was piled high
with evergreens. Suddenly Mollie started. She thought she heard a voice
calling from somewhere above their heads. "Hi, there! Hello! Hello!"

"Did you hear some one calling?" asked Mollie.

"Why, no," responded Barbara. "What is the matter with you, Mollie? This
morning you heard a 'spook' outside the door, this afternoon you believe
you hear a voice calling you. Beware, child! Perhaps you are already
afflicted with the wood madness, and may see that wonderful ghost."

"Hi, there! Hi, there!" A voice was surely floating down from the sky.

This time Bab stared. Mollie looked triumphant. As far as they could see
around them, there was no other human creature. And the sound did not
come from the ground. Mollie was right. The noise was from overhead. But
it was so far off and faint, it could not come from the trees above them.

Bab and Mollie ran out into an open space. There was a strange, rattling,
swinging noise above their heads, as though a pair of mammoth wings were
beating in the sky. The two girls looked up. There, about twenty yards
above the tops of the highest trees was the strangest object ever seen by
Mollie and Bab!

"W