The two started together for the projectile. The stout one entered
first, and made his way through the engine room and main cabin to the
compartment off which the staterooms opened. He entered one.

"Here, that's not yours," cried Jack. "That's where Professor Henderson
sleeps. Yours is next to mine."

"That's right; I forgot," mumbled the other. "I must be getting absent
minded since my accident. But I'll be all right soon. I'll get my room
to rights, and then probably we'll start."

"I guess so," answered Jack, but he shook his head as he gazed after
his chum. "Mark has certainly changed," he murmured. "I wish he'd take
those bandages off, so I could get a look at his face."

The last details were completed. The big _Annihilator_ had been run out
on trucks into the yard surrounding the shed, ready to be hurled
through the air. The shop, shed and house had been locked up and given
in charge of a caretaker, who would remain on guard until our friends
returned.

"Are we all ready?" asked Professor Henderson, as he stood ready to
close the main entrance door and seal it hermetically.

"All ready, I guess," answered Jack. The stout one had gone to his
stateroom, where he could be heard moving about.

"I'm ready," announced Professor Roumann. "Say the word and I'll start
the motor." He was in the engine room, looking over the machinery. At
that moment there came a loud yell from the galley where Washington