It was the best course open to her. The depth of the water was much too great to allow her to rest on the bed of the sea. On the other hand, in order to keep submerged, the motors would have to be in motion. No one knew better than Schwalbe that the British patrol-boats would be in a position to locate with uncanny certitude the presence of their quarry, unless the strictest silence were maintained by the fugitive.
So, ready to dive at the first alarm, U75 floated awash until such times as were considered favourable for getting under way. Decidedly this part of the English Channel was, for the time being at least, unhealthy; and Kapitan Schwalbe resolved to make for the Bristol Channel, where the dangers of being destroyed by modern mosquitoes were more remote.
Meanwhile Ross and Vernon had been sent back to the quarters in the alley-way, by the side of the motor-room. Not knowing the reason for the U-boat's sudden submergence, and consequently unaware of the danger that threatened her, they formed the erroneous impression that the submarine was about to attack.
"The old fellow gave us a pretty straight tip," remarked Vernon, when the chums found themselves alone. "All the same, I vote we get out of it at the first opportunity, favourable or otherwise."
"'Ssh," whispered Ross. "Someone might be listening. I don't see how you propose to clear out, though."
"We were on deck just now."
"We were," agreed Trefusis.
"It was fairly dark. All the men up for'ard were lying down. It would have been an easy matter to have dived overboard and swum for it, if we hadn't been twenty miles or more from land."
"There was a bright look-out kept, all the same," objected Ross. "And I wouldn't mind saying that if the submarine were closer inshore, getting a supply of petrol, for example, we should be closely watched. All the same, I'm with you if we get the ghost of a chance. But it's a rummy affair altogether. Fancy that chap knowing our names and the rank of our respective fathers."
"Ramblethorne must have told him that," said Vernon.