By mid-afternoon, they were approaching Pennsylvania. The drizzling rain had changed to snow and sleet. Then they were forced down. The ship's air-speed fell off with an alarming suddenness. Then the entire tail structure took on a heavy load of ice.

They settled tail-down into a clearing on a densely wooded slope. The ship wallowed deep into the soft, slushy snow.

The three men got together over the table in the forward lounge. Foster kept running his hands through his hair, nervously. "We're stuck," he said. "We're stuck here for the winter unless we can rebuild the tail assembly. That jet chamber has to be changed."

It was obvious, after they had diagrammed the readings from their various flight-test instruments. The ship's hull had become completely polarized to the gravitors' field; the field influenced the air flowing over the hull, so much so that a simple air-scoop couldn't pick up air to blow through the propulsion unit and out the tail-jets. The air intake had to be designed to work on the disturbed air-flow.

"It's a little like those 'space-warps' in science-fiction yarns," Foster explained. "There's a warp of the gravitational and magnetic fields around the ship. The air-flow entering that warp bends and twists to follow it."

"We ought to redesign the entire hull to comply with that warped air-flow," Smitty suggested absently.

"The hull doesn't matter so much," Foster contradicted. "We could design it in any shape, though a sharp nose and thin guide-fins are still effective. You just happened to hit the right answer when you placed the control-surfaces forward on the nose of the ship."

"Talking isn't going to get us out of here," Morrow remarked grimly. "Let's get to work on that tail assembly."

"I got news for you!" Smitty muttered. "If we rebuild the tail with our power-tools, it'll use up the juice in our batteries. We won't have enough to get home."

"We must get our batteries recharged, then," Morrow said. "Will we have enough juice left to get out of here when we're finished?"