"Where in blazes have I seen that chap before?" wondered Captain Jack Benson, staring hard. "For I have seen him—somewhere. I'd declare that under oath."
Figure, carnage and face all strangely haunted the submarine boy, who crouched lower, watching.
"By the great turret gun! He's skulking for a reason!" muttered Benson. "Is he spying on the mine-planting? I wonder? Yes! That must be his work! Long-legs, I'll keep my eyes on you!"
The stranger hastened along for perhaps a quarter of a mile further. Then he threw himself down on the sand, choosing a position in which he could lie flat, his head fairly well hidden behind a low ridge of sand.
Unslinging the field-glass, the stranger brought it to his eyes, closely watching the progress of the tug.
"Ha-ha!" muttered watchful Jack, who had followed, keeping behind another sand ridge. "So, sir!"
The minutes passed, though Jack Benson was so absorbed in watching this long stranger that the boy had but the vaguest notions of the flight of time.
The tug had halted, now. A great crane at the bow swung around, and a submarine mine hung poised in the air. Then, with a rattle of chains not audible at the distance, the mine was slowly lowered until it touched on bottom.
While this was going on, the long-legged stranger, wholly absorbed in his own work, made some observations and some hurried calculations. Then he pulled the drawing-board toward him, jotting down a point.
Jack Benson, standing stealthily, got a good look, for the first time, at the top of that drawing board.