The inventor smiled.
"There is no danger," he said, "until the other current is turned on."
Marbeau's face was livid and beaded with perspiration. He wiped it with a shaking hand.
"Nevertheless you startled me," he said. "The sound the machine makes has a frightful menace in it!" Then he looked at his watch. "It is now eleven."
Vard nodded, and bent again above his apparatus, touching it here and there with the touch of a lover—tightening a wire, examining a contact, testing the vibrator....
His usual pale face was flaming with excitement, and his eyes shone with a strange fire.
Marbeau glanced at him uneasily, then stared out at the grey wall of the arsenal. Upon its summit a sentry walked to and fro with the precision of a machine. High above him flapped the imperial flag of Germany, displaying its eagles and complacent motto. Marbeau, like every Frenchman, considered that flag an insult, for the lower arm of its cross bore the date "1870," and he stared out at it now, dreaming of the future, dreaming of the day when France should tear it down....
Vard touched him on the arm.
"I should like to see the plan of the fort again," he said.
Marbeau opened his shirt, and from a little oilskin bag produced a square of tracing-paper. He unfolded it and handed it to the inventor.