g to give the motors a good try-out," observed Tom. "I
think I'll go back to the engine room. You may remain here, if you
like, and you'll probably see--"

A cry from Mr. Damon interrupted him.

"Bless my rubber boots, Tom! Look!" cried the eccentric man. "We're
going to ram a mud bank!"

As he spoke they all became aware of a solid black mass looming in
front of the bull's-eye window. An instant later the submarine came to
a jarring stop, as if she had struck some soft, yielding substance.
There was a confused shouting throughout the craft, the noise of
machinery, a trembling and vibration, and then ominous quiet.

CHAPTER IX

READY TO START

Characteristic it was of Tom Swift to act calmly in times of stress and
danger, and he ran true to form now. Only for an instant did he show
any sign of perturbation. Then with calmness and deliberation the young
inventor quickly did a number of things to the controls within his
reach.

First of all he signaled to the engine room that he was going to take
charge of the boat. This meant that the navigator in the conning tower
was to keep his hands off the various levers and wheel-valves. It was
possible to operate the M. N. 1 from three positions, but Tom wanted no
triplicate handling of his craft now.

Almost the instant Tom signaled that he would take charge back came
flashing the electrical signal from the conning tower that his orders
were understood. The next thing that those aboard the craft became
aware of was a tremor that seemed to run through the whole under-sea
ship. The quiet had changed to a subdued humming, and the ominous lack
of motion was succeeded by violent vibration.

"Backing her up, Tom?" asked Ned, in a low voice.

"Trying to," was the answer. "But I'm afraid her nose has gone in
pretty deep. I've reversed the propellers."

For perhaps a minute this vibration continued, showing that the
powerful electric motors were turning over the twin propellers at the
blunt stern of the craft. But she did not change her position.

With a touch of his hand, and still almost as cool as the proverbial
cucumber (though why they should be cool it is hard to say), Tom
stopped the motors. Once again the craft was quiet, but now, instead of
the occupants being able to see clearly from the thick, glass windows
in the forward cabin, the water showed muddy and murky in the glare of
the underwater searchlight.

"Bless my postage stamps, Tom! what has happene