"Where's Mark? Wasn't he helping you catch the rooster?"

"No, he's inside. Shall I seal the door?"

"Yes, and I'll tell Professor Roumann that we're about to start. All
ready for the moon trip!"

Jack was pulling the steel portal toward him. An eager face, peering
from a port, waited anxiously for the tremor which would indicate that
the projectile had left the earth. In another moment they would be off.

But what was that sound coming from down the highway. A steady chug-
chug--a sort of roar, as of a battery of rapid-fire guns going off in
double relays! And, mingled with the explosions, there was a voice
shouting:

"Wait! Hold on! Don't go without me! I'm Mark Sampson! Don't start the
projectile!"

"Somebody must be in a mighty hurry on a motorcycle," thought Jack, as
he paused a moment before fastening the door. Then the shouts came to
his ears.

"Mark Sampson!" he cried.

Again came the cry: "Wait! Wait! Don't go without me! You've got that
mysterious man on board!"

"Mark Sampson!" murmured Jack again. "That's his voice sure enough! I
wonder--can it be possible--that man--with his head all bandaged up--