“That’s what!” agreed Ned.

Even as they spoke the roar of the airship motor increased.  Several of the dark forms which had been engaged in the struggle with Koku were seen to pick themselves up, and run toward the airship, that was now in motion, moving on the bicycle wheels over the grass plot, preparatory to mounting upward in the sky.

“Stop!  Stop!” commanded Tom.  But it was all in vain.

The men leaped aboard the airship, which could carry six persons, and a moment later, with a deafening roar, as the engine opened up full, the big craft shot upward, taking away all but two of the midnight visitors.  These, who had seemingly been stunned by Koku, now arose from the ground, and staggered off in the darkness.

“Get them!” cried Tom.

“We must see to Koku!” added Ned, “Look, there goes your airship, Tom!”

“Yes, I know.  But we can’t stop that now.  Let’s see if we can get a clue in these fellows!”

He pointed toward the two who had run off in the dark underbrush surrounding the hangar plaza, and he and Ned trailed them as well as they could.  But from the first they knew it would be useless, for there were many hiding places, and, a little way beyond, was a clump of trees.

After a short search Tom gave up reluctantly, and came back to where Koku was now sitting on the ground.

“Are you hurt?” he asked of the giant.

“My mind hurt—­that all,” said the big man.

“I guess he means his feelings are hurt,” Tom explained.  “Do you know who they were, Koku?”

“No, master.”

“But we must do something!” cried Ned.  “They’ve got your airship, Tom.”

“I know it,” said the young inventor, calmly.  “But we can’t do anything now.  You can hardly hear her, let alone see her.  She’s moving fast!”

He pointed upward to the darkness.  Like some black bird of prey the airship was already lost to sight, though it would have seemed as if her white planes might render her visible.  But she had moved so swiftly that, during the short search, she had already disappeared.

“Aren’t you going to do anything?” asked Ned.

“Certainly,” spoke Tom.  “I’m going to telephone an alarm to all the nearby towns.  This is certainly a queer game, Ned.”

CHAPTER XII

A STRANGE DISAPPEARANCE

Disappointed and puzzled, Tom and Ned went to where Koku was standing in rather a dazed attitude.  The giant, like all large bodies, moved slowly, not only bodily but mentally.  He could understand exactly what had happened, except that he had not prevailed over the “pygmies” who had attacked him.  They had been too many for him.

“Let’s take a look inside,” suggested Tom, when, by another glance upward, he had made sure that all trace of his big airship was gone.  “Maybe we can get a clue.  Then, Koku, you tell us what happened.”