The search for that key went on among the records and artifacts. The repository itself was searched inch by inch—and still almost none of the artifacts found there could be identified or explained. Apart from the repository, most of the material they had was native to the planet on which the Sirenians landed.
By the eighth day Mason's crew had managed to construct equipment for throwing a force shell about the Lavoisier, and Underwood breathed considerably easier. They could travel indefinitely behind the protection of that impenetrable shield. Data for navigation was obtained through almost infinitesimal pilot units set outside the shell and connected through hair-fine leads running through equally small holes in it.
Underwood was proud of this accomplishment. With their limited facilities for manufacture, it was little short of a miracle that they had been able to turn out the mass of complex equipment in so short a time. Somehow, it seemed symbolic to him, as if there were definite laws favoring their success—the success of Earth.
And then on that same eighth day, when they were almost beyond the limit at which such small, dark objects could be identified, the lookout observer on duty sounded a warning to the control center.
"Fleet departing from Earth. Twenty warships. Corius type. Apparent course 169 46 12 and 48 19 06. Velocity—"
Underwood looked at Phyfe, who was beside him at the time. "This is it," he said.
The warning went throughout the ship and the men looked up from their tasks a moment, then resumed with grimmer eyes and firmer mouths. Mason's group was working on the problem that had baffled armament men for generations, the problem of firing the Atom Stream through the force shell. Underwood had little confidence that they would solve the problem, but as it was they had no offense whatever.
As Underwood and Phyfe moved to the navigator's table to check their course and that of the pursuing fleet, he said, "I wonder how they spotted us. Our echo screen couldn't have broken down. It must have been sheer astronomical luck that put them on our trail."
Lieutenant Wilson, the navigator, frowned as he pointed to their course charts. "I don't believe that fleet is following us," he said. "If they are, they're going the long way around, because their course at present is heading more than fourteen degrees from ours."