fish, or anything else of moment. Even in the bay we won't see
much to attract our attention. But I want to make sure everything
is working smoothly before we start for the West Indies."

"That's right!" agreed Mr. Hardley. "We want to make a success
of this trip."

He remained at the glass bull's-eyes, now and then exclaiming
as some shad or other fair-sized fish came into view. Suddenly,
however, his exclamation was sharper than usual.

"Look!" he exclaimed. "There's part of a wreck!"

Ned, Mr. Damon, and Tom looked out and saw, sweeping past them,
the ribs and worm-eaten timbers of some craft, lying on the
bottom of the river.

"Yes, that's the remains of an old brick scow," the young
inventor explained. "That's one of our water-marks, so to speak.
It is at the bend of the river. We turn now, and head for the
bay."

As he spoke they all became aware of a sudden swerve in the
course of the submarine. The helmsman had, doubtless, noted the
"water-mark," as Tom termed it, and as an automobilist on land
might swing at the cross-roads, the steersman was changing the
course of his craft.

"We'll go deeper," said Tom a moment later, as the wreck passed
out of view. "We can go about fifty feet down now. Yes, he's