father if anything happens to
you?"

"Dad wouldn't want me to stand back at a time like this," rejoined the
young inventor. "I sent these men down and it's up to me to see they get
back safely!"

"But, Tom!" cried Ned. "What of the octopus? You may be trapped too, and
not save Manuel and Alvarez either!"

[Illustration: "It's up to Me!"]

"You forget, or maybe you didn't know, that I brought my electric rifle
with me. That'll polish off any devil-fish I'm likely to meet!"

"Well, at least let me go too!"

"Isn't but one suit," said Captain Britten. "Now, Tom Swift, if you're
ready, here's the suit."

"All set," said the young inventor calmly. He began to remove his outer
clothing. "Ned, please bring up my rifle."

By the time the young scientist had been helped into the massively
armored suit, Ned was back on deck carrying a peculiar-looking gun.
Unlike other weapons, this one could discharge a bolt of electricity
which would slay the largest animal or merely tickle a baby, according
to the adjustment. Tom set it to its highest power.

[Illustration: They Helped Tom into the Suit]

"Good luck!" cried Ned as the heavy helmet was lowered into place.

Tom attempted to wave in reply but the gear was too weighty. Later, when
he got into the depths, the buoyant effect of the water would enable
him to move more freely.

[Illustration: Ned Carried a Peculiar Gun]

Clutching his gun in his armored hand, Tom crept slowly on to the
platform suspended over the sea. As it was lowered to the water he got a
last glimpse of Ned Newton's face staring down at him.

The young business manager paced the deck of the barge, at every step
reproaching himself for allowing his chum to undertake so hazardous a
venture. As his watch told him that Tom must be nearing the bottom he
seated himself by the switchboard, headphones clamped over his ears.

[Illustration: Tom Crept Slowly to the Platform]

"Ground floor," announced Tom at last. "Pretty dark down here. I'll
switch on my flash. Now--by George!"

Ned heard a muffled silence.

"Tom! Tom!" he shouted frantically. "What's happened? Are you all
right?"

For nearly ten minutes Ned crouched by the instrument trying to get in
touch with his friend. Just as he was giving up hope he heard a weak
voice gasp:

[Illustration: "Ground Floor," Announced Tom]

"Not so loud, old man! You've nearly broken my ear-drums. Everything's
under control!"

"Hurray!" shouted Ned. "He's f