"And what time-fuses?"
"Four-minutes," was the reply.
"Then jolly rotten stuff," commented the lieutenant-commander as he motioned for the prisoner to be removed below. "We'll give them another quarter of an hour before we board her."
The stated time passed without any signs of further internal explosions. The Calder made good use of the interval, Harwich being communicated with by wireless, announcing the capture of the prize, and requesting tugs and lighters to be dispatched to assist the disabled U boat into port.
"Now I think it's all O.K.," remarked Crosthwaite. "Sure you're keen on the job?"
Sefton flushed under his tanned skin. His skipper was quick to notice that he had blundered.
"Sorry!" he said apologetically. "Ought to have jolly well known you better. Off you go, and good luck. By the by, take a volunteer crew."
Of the seventy men of the Calder every one would have unhesitatingly followed the sub. Asking for volunteers for a hazardous service was merely a matter of form. There was quite a mild contest to take part in the operations of boarding the submarine.
By this time the falling tide had left nearly the whole extent of the deck dry. There were four hatchways in addition to the conning-tower, each of which was securely fastened. Through the open aperture in the conning-tower Sefton made his way. Below all was in darkness, for with the explosion the electric lamps had been extinguished. A heavy reek of petrol fumes and sulphurous smoke scented the confined space.
The sub switched on the electric torch which he had taken the precaution to bring with him. The rays barely penetrated the smoke beyond a few feet.