They followed the curving fence cautiously and on the alert. Biff took the lead. They continued until Biff figured they had covered ninety degrees of a gigantic circle. The fence remained an equal distance from the rim at the top as they followed the path.
“Hold it!” Biff held up his hand. Then he motioned Muscles and Chuba forward.
“Look,” Biff pointed to a gap, wide enough and deep enough for a man’s body to slip beneath the fence.
“Some animal must have been as curious as we are,” Biff said. “Something burrowed under the fence.”
“Well, what are we waiting for?” Muscles grinned. He dropped to his hands and knees and wiggled through the opening. Chuba followed, and Biff brought up the rear.
Crouching low, the three approached the top of the rise. They crawled the last few feet, reached the rim, and raised their heads slowly. What they saw made them all gasp.
They were looking into an immense bowl, covering an area so great it was impossible to take it in with one look. They pivoted their heads, following the rim of the bowl.
The activity on the floor of the bowl made them squint their eyes in disbelief. Everywhere they looked they saw bulldozers, huge cranes, steam shovels, and thousands of men working furiously. The bottom of the bowl was so far away that the working men seemed like small moving specks. The noises of the steam shovels digging into the earth and the whines of the huge crane arms turning on their metal discs rose only dimly to the ears of the astonished spectators.
Toward the opposite side of the huge bowl, two cement runways in the shape of a plus sign were dotted with planes.
In still another section of the bowl, great steel trylons, resembling oversized high-tension wire supporters, reared skyward.