"But surely no shell would reach us here," said Frank.
"No," replied the commander grimly, "but if they discover us, they are likely to dump a few barge loads of pig iron or something down on us and crush our steel plating."
But the submarine was not discovered by the enemy and remained below the water all the rest of the day "went to sleep on the bottom," as the phrase goes. And that is what literally was done, for all on board were tired out.
An hour after sunset, the Y-3 came once more to the surface. There was no sign of an enemy. The sky was still banked with heavy clouds, and there was a choppy sea running.
Captain Nicholson started to run for safety at full speed ahead. Having no batteries for submerged running now, the Y-3 had to remain on top of the water, or else sink to the bottom and lie still; and for this reason Captain Nicholson kept prepared for a quick submersion.
Mines were the worst dangers the Y-3 bad to encounter now, and a careful watch was kept and the speed of the vessel reduced. Twice the vessel was picked up by the searchlight on the fort, and each time submerged.
But the engines stood up well, and at last Captain Nicholson said quietly to the two lads:
"Well, we're safe at last."
"Good," said Frank, "but I wouldn't have missed this experience for a fortune."
"Nor I," declared Frank.