All the boys laughed, including Jimmie, for they knew that what Frank said was the truth. Jimmie liked to talk of merciless measures, but he was not inclined to put them into practice.
"Well," Ned said, presently, "the Diver people will soon understand that something has happened to Moore, and will be after us. We may as well take a moonlight stroll."
The water tanks were filled, the power turned on, and the Sea Lion, with no lights in sight, save the one at the prow from which Frank watched the level ahead, began feeling her way to the south.
"The charts show a deep pit not far off," Ned said, "and we'll hide there for a time and see if they give up the job of looting the wreck. The loss of young Moore may scare them out."
"Why not go to the surface and air out the boat?" asked Jack. "Our air apparatus is all right, of course, but I like the real thing better. We can drop down again in a few minutes."
"That's a good idea," Ned replied, and in a moment the Sea Lion was lifting to the surface.
In half an hour she was down again, dark and silent, in the pit of which Ned had spoken. Occasionally the submarine was lifted a few fathoms in order that anything unusual in the vicinity of the wreck might be observed.
Sometime near morning the Diver was seen making her way to the north as if setting out for a long voyage. The lights of the craft showed plainly—that is, as plainly as lights ever show at that depth—and the Sea Lion had no difficulty in following her.
"She's steamin' up!" Jimmie cried, presently. "I believe she knows we're after her."
But the Sea Lion was equal to the task set for her, and all the remainder of the night the chase went on.