The lights that gleamed across the billows came from the convoying destroyers, and signals flashed from one to the other, though the meaning of them the moving picture boys could only guess at.
Immediately following the explosion, which seemed to come from the side of the Jeanne where Labenstein had flashed his signal, the German and the Frenchman had subsided into silence. Each one had given voice to an exclamation in his own tongue and then had hurried away.
And so occupied were Blake and his chums with what had gone on out there on the ocean—trying to guess what had happened—that they did not notice the departure of the two men.
"What's that you said it was?" asked Joe of his partner. "I mean the explosion."
"I think it was a depth charge," answered Blake. "One of the destroyers must have sighted a submarine and let go a bomb, with a heavy charge of explosive, which didn't go off until after it got to a certain depth below the surface. That's the new way of dealing with submarines, you know."
"I only hope they got this one, with a depth charge or any other way," remarked Charles Anderson. "Look, we're lighting up! I guess the danger must be over."
Lights were flashing on the deck of the Jeanne, and signals came from the destroyers. It was evident that messages were being sent to and fro.
And then, as passengers crowded up from their staterooms, some in a state of panic fearing a torpedo had been launched at the ship, another muffled explosion was heard, and in the glare of the searchlights from one of the convoying ships a column of water could be seen spurting up between the French steamer and the war vessel.
"That's caused by a depth charge," Blake announced. "They must be making sure of the submarine."
"If they haven't, we're a good target for her now," said Joe, as he noted the lights agleam on their steamer. "They're taking an awful chance, it seems to me."