“Rise?” said Frank. “What for?”
“Because,” was the reply, “the water is very shallow just ahead, and we shall run aground. We are now approaching the entrance to the canal.”
Frank looked at his captive long and searchingly. There was still a doubt of the German’s honesty of purpose in his mind, and for a moment he was undecided.
“We must rise at once,” said the German.
Frank made his decision quickly. “Very well,” he said quietly.
He stepped to the signal tube and gave the necessary order. A moment later the rising of the vessel became perceptible, as the water was slowly forced from her tanks.
Frank, not perfectly satisfied, however, stood facing the German officer, his hand on his revolver, determined to use it at the first sign of treachery.
But his uneasiness was without cause. When the submarine had risen the required distance, at a word from the German, her speed was increased and she moved forward again.
“Is there not danger of striking a mine up here?” asked Frank.
“There are a few about,” was the reply, “but I can guarantee that we shall not strike one. When the depth of the water permits, we shall go lower again.”