His boots made squelching noises as he slogged through the ooze toward the barrel. The commander of the machine stuck his head out of the central cupola that gave him and his driver a place to perch and a better view than the machine gunners and artillerymen enjoyed (the engineers who tended the two motors had no view, being stuck in the bowels of the barrel).

"Sorry, sir," he said. "Couldn't spot that one till too late."

"One of the hazards of the game, Jenkins," Morrell answered. "You can't go forward; that's as plain as the nose on my face. See if you can back out."

"Yes, sir." Lieutenant Jenkins ducked down into the cupola, clanging the hatch shut after himself. The engines changed note as the driver put the barrel into reverse. The barrel moved back a few inches, then bogged down again. Jenkins had spunk. Having shifted position, he tried to charge forward once more and escape the grip of the mud. All he succeeded in doing was getting deeper into it.

Morrell waved for him to stop and called, "You keep going that way, you'll need a periscope to see out, just like a submersible."

He doubted Jenkins heard him; with the engines hammering away, nobody inside a barrel could hear the man next to him screaming in his ear. Even so, the engines fell silent a few seconds later. The traveling fortress' commander could see for himself that he wasn't going anywhere.

When the young lieutenant popped out through the hatch again, he was grinning. "Well, sir, you said you wanted to test the machine under extreme conditions. I'd say you've got your wish."

"I'd say you're right," Morrell answered. "I'd also say these critters need wider tracks, to carry their weight better."

Lieutenant Jenkins nodded emphatically. "Yes, sir! They could use stronger engines, too, to help us get out of this kind of trouble if we do get into it."