The Dennings surveyed the building, but found no entrance. It must have been a quarter of a mile around its walls, but there was no sign of a door or entry. The wall was of a rocklike substance, but it was not like any rock or plastic Burl had ever seen.
"We've got to get in," said Burl as they returned to the starting point, "but how?"
His father smiled. "This way." He opened his pack and took two cans of blasting powder from it. "I thought these would come in handy. Lucky we had some left over from the blasting we did last week."
He set both cans at the base of the high wall, wired them together, and ran the wire as far as it reached. When the two men were a safe distance away, Mark sparked off the explosive.
There was a thunderous roar: rocks and dirt showered around them, and bits of black powdery stuff. When the smoke cleared, Burl and his father leaped to their feet, rifles in hand.
There was a crack in the side of the wall where the explosive had gone off. And the rip was large enough to get through!
Without a word, they charged across the ground, still smoking from the concussion, and squeezed through the mysterious walls of the enigmatic building.
The walls were thin, thin but hard, as befit masters of atomic engineering. Inside, they found a roomless building—one single chamber within the frame of the outer walls.
A dim, bluish light emanated from the curving ceiling. On the uncleared rocky ground which was the floor of the building were a number of huge machines.
They were spherical glassy inventions, many times the height of a man, connected by strings of thick metal bars and rows of smaller globes, none of which was familiar. There was a steady humming noise, and above, the two giant, metal masts penetrating the ceiling rotated slowly. Doubtless, the great Sun-trapping discs were affixed to the top of these masts.