The distant squawk of a jay became suddenly very clear, as did the sighing of a faint breeze through the leaves overhead. Then a new, clanking, humming sound intruded. A procession of three vehicles rolled along the highway at an unvarying pace which took no account of patches or worn spots. They jounced in turn across a patch laid over a previous, unsuccessful patch, and halted before the felled tree. Two were bulldozers; the third was a light truck with compartments for tools. No human figures were visible. A moment later, the working force appeared--a column of eight robots. These deployed as they reached the obstacle, and explored like colossal ants along its length. "What're they after?" asked Mike, whispering although he lay fifty yards away. "They're lookin' over the job for whatever sends them out," Blackie whispered back. "See those little lights stickin' out the tops o' their heads? I heard tell, once, that's how they're run." Some of the robots took saws from the truck and began to cut through the tree trunk. Others produced cables and huge hooks to attach the obstacle to the bulldozers. "Look at 'em go!" sighed Sid, hunching his stiff shoulders jealously. "Took us hours, an' they're half done already." They watched as the robots precisely severed the part of the tree that blocked the highway, going not one inch beyond the gravel shoulder, and helped the bulldozers to tug it aside. On the opposite side of the concrete, the shoulder tapered off into a six-foot drop. The log was jockeyed around parallel to this ditch and rolled into it, amid a thrashing of branches and a spurting of small pebbles. "Glad we're on the high side," whispered Mike. "That thing 'ud squash a guy's guts right out!" "Keep listenin' to me," Blackie said, "an' you'll keep on bein' in the right place at the right time." Mike raised his eyebrows at Vito, who thrust out his lower lip and nodded sagely. Sid grinned, but no one contradicted the boast. "They're linin' up," Blackie warned tensely. "You guys ready? Where's that rope?" Someone thrust it into his hands. Still squinting at the scene on the highway, he fumbled for the ends and held one out to Mike. The others gripped their clubs. "Now, remember!" ordered Blackie. "Me an' Mike will trip up the last one in line. You two get in there quick an' wallop him over the head--but good!" "Don't go away while we're doin' it," said big Sid. "They won't chase ya, but they look out fer themselves. I don't wanna get tossed twenty feet again!" The eyes of the others flicked toward the jagged white scar running down behind Sid's right ear and under the collar of his jacket. Then they swung back to the road. "Good!" breathed Blackie. "The rollin' stuff's goin' first." The truck and bulldozers set out toward the city, with the column of robots marching a fair distance behind. The latter approached the ambush--drew abreast--began to pass.