“I have an idea that the plotters arranged for that,” Ned said, then.
“But how?” demanded Welch. “The plants are well guarded. You know, of course, that we are all on the lookout for something of the kind? We thought we had provided against any sudden surprise. Where are we to look for them?”
Then Ned pointed out the probable points of attack, and Welch sprang to his feet in a fuming passion.
“The spillway and the locks,” he cried. “And the point where the soft earth extends under the dam! Come!”
“Bring four of your men who can be trusted,” Ned advised, not leaving the box.
“Yes, and what then?”
“Send a man to the light station and have tracers sent out, but instruct him not to have the lights turned on until you give the signal.”
“I understand,” the foreman said. “We’ll catch them with the goods!”
Four men, workmen, were strolling along the danger points within five minutes, and another moved toward the electric switches which governed that part of the illumination. Ned and Welch remained near the spillway. The three boys, after whispered instructions from Ned, moved along the line passing word from man to man.
It was a long and heart-breaking half hour, seemingly double that time, that followed. The man from the switches came back and whispered to Welch, and at that moment a shrill bird-call sounded in the darkness. This, in turn, was followed by the report of a revolver, and then the light leaped into the globes, making the place, the entire length of the canal dam, the spillway and the locks, as bright as day.