d saw his friend beckon,
and ran down the pier to the house. The scientists joined him and Scotty
at the shed where the compressor had been stored.

"We've been sabotaged again," Scotty told them flatly. "There's oil in
the compressor!"

"Are you certain?" Zircon pressed close to examine the machine.

"Yes. I stumbled over my own feet and tipped the compressor on its side.
And oil ran out through the air fitting. Look!" Scotty held up his hand,
and it was smeared with glistening oil.

A cold shiver traced its way down Rick's spine. Oil in a compressor was
blown into fine particles, too small to be seen. If they got into an air
tank they would be breathed in, leaving a thin coating on a diver's
lungs. The result was a condition almost exactly like pneumonia, called
"lipoid pneumonia." Their special filter, designed by Zircon, probably
would have taken all the oil particles out of the air before it got into
the tanks, but that didn't alter the fact that faced them. Someone had
deliberately put oil in the compressor. Someone just didn't want them
around!

CHAPTER VIII

The Fancy Frogmen

"The question is," Rick stated, "when was the oil put in? While we were
at Charlotte Amalie? Or while we were out hunting the wreck just now?"

"In Charlotte Amalie, of course," Tony said. "Why do you think it might
have been done just a little while ago?"

Rick shrugged. He had no answer to that. The question had popped into
his mind unbidden.

"We didn't take the compressor apart," Scotty reminded him.

That was true. But Rick had started it in Charlotte Amalie to be sure it
was functioning. There was no oil in it then. He said as much.

"You started the compressor at the same time you checked the tanks,"
Zircon reminded him. "I believe the oil was put in at the same time the
valves were loosened."

That seemed reasonable. Rick put aside his hunch. "Well, we found it in
time, anyway. Now Scotty and I will have to tear the compressor down and
clean it before we can recharge the tanks."

"After lunch," Tony said. "Don't you remember? A diver is supposed to
rest after each dive. Relax, and I'll have some sandwiches ready in a
few minutes."

All hands were hungry. Scotty stowed away four sandwiches and Rick did
nearly as well. Then they started work on the compressor. It wasn't a
hard job, but it was tedious, and nearly two hours elapsed before they
finished. Each part had to be washed in soap and water, then caref