It took them a week to pull out the rear bulk-heads and completely redesign and reconstruct the tail-jet assembly. When they finished, they tried it again. They got an air-speed of seventy m.p.h. at low level, but it dropped to twenty m.p.h. as they gained altitude. The tail-jets didn't just make a whooming sound, this time--they made a rumbling, burbling sound. They landed and pulled the ship into the workshop, closing the big doors after it. Morrow walked over to the workbench, pulled off his gloves, and threw them down. "It's no good!" he said harshly. "That jet chamber just isn't shaped right--there's too much turbulence in it, breaks up the jet-blast." "We'll rebuild it again," Smitty said, with a shrug in his voice. Morrow wheeled and glared at him, red-eyed. "We aren't jet engineers, Smitty. We're building by guesswork! We can redesign that jet chamber a thousand times and never get the right shape!" Smitty moved on to the stove and began stoking up the red coals, stacking wood on them. "She does seventy per hour up to seven thousand feet," he said dully. "If that's the best we can do, we'll just have to be satisfied with it." "It's not _good_ enough!" Morrow protested. "She _has_ to have more speed, Smitty. She'll be at the mercy of every wind that comes along if she hasn't, weightless as she is!" He smacked his fist into his palm, decisively. "We've got to get help, chum." "Help?" Smitty turned and looked at him, querulously. "Where can we get help?" "A jet engineer," Morrow snapped irritably. "That's the only one who _can_ help us. We've got to find one--" He broke off, suddenly thoughtful. Smitty grinned without mirth, mistaking his silence for hopelessness. "That's the trouble, Bill," he said. "There's no one who _would_ help us!" "I'm not so sure about that!" Morrow replied softly. "_I'm not so sure at all--_" * * * * * It was late Friday afternoon when Morrow parked the battered, mud-splattered truck on a side-street and climbed out to go for a quiet stroll in suburban Sacramento. The street address he was looking for turned up in the next block, near the edge of town. It was an inconspicuous one of the long street-row of small houses with a green lawn stretching down to the curb and dotted with a few evergreen shrubs, a broad livingroom picture window in front, a white front door with a small ornamental iron night-lamp mounted above it, and a one-story, red-tiled roof in the flat, gently sloping California style.