"Well, I think you'll find Mr. Hardley all right," said Mr.
Damon, who seemed to have taken a strong liking to his new
friend.

Certainly the latter showed no signs of nervousness as the
craft slowly settled to the proper depth. He asked numberless
questions, showing his interest in the operation of the M. N. 1,
but he showed not the least sign of fear. However, as Tom said,
that might come later.

"We are going down now," Tom explained, as he pointed out to
Mr. Hardley the various controlling wheels and levers, "by
filling our ballast tanks with water. We can rise, when needful,
by forcing out this water by means of compressed air. When we are
on the ocean we can go down by using our diving rudders, and in
much quicker time than by filling our tanks."

"How is that?" asked the seeker after the Pandora's gold.

"Filling the tanks is slow work in itself," replied Tom, "and
they have to be filled very carefully and evenly, so we don't
stand on our stern or bow in going down. We want to sink on an
even keel, and sometimes this is hard to accomplish. But we are
doing it now," and he called attention to an indicator which told
how much the M. N. 1 might be listing to one side or to one end
or the other.

"A submarine, as everyone knows, is essentially a water-tight
tank, shaped like a cigar, with a propeller on one end. It can
sink below the surface and move along under water. It sinks