ere you can get in, and those fellows will never know it. And,
what's more, I'll help you if it comes to a fight!"

"Good!" exclaimed Mr. Jenks. "I think we'll discover the secret of the
diamond makers this time," and he went to tell the others of the success
of his talk. Bill Renshaw had been converted from an enemy into a
friend, and the former phantom was now ready to lead Tom and the others
into the secret cave.

"We'll start in the morning," decided Mr. Jenks, who, after many
disappointments, at last saw success ahead of him.

CHAPTER XIX--IN THE SECRET CAVE

Tom Swift was up at break of day, and the others were not far behind
him.

"Now for the secret cave!" cried the young inventor as he gazed up
the mountain, in the interior of which the mysterious band of men were
making the diamonds.

"Have you made any plans, Bill?" asked Mr. Jenks of the former phantom,
who had cast his lot in with the adventurers. "What will be the best
course for us to follow?"

"You just leave it to me, Mr. Jenks," was the answer. "I'll get you into
the cave, and those fellows, who, I believe, are trying to do me out of
my rights, as they did you out of yours, will never know a thing about
it."

"Bless my finger-nails!" cried Mr. Damon. "That will be great! We can
get in the cave, and watch them make the diamonds at our leisure."

"They don't make them every day," explained Renshaw. "It seems they
have to wait for certain occasions. Mostly they make the diamonds when
there's a big storm."

"A big storm," asked the scientist with a sudden show of interest.
"Do you mean one of those electrical storms, such as we had the other
night?"

"That's it, Mr. Parker, though why they wait until there's a storm is
more than I can tell."

"Perhaps they know that on such occasions no one will venture up the
mountain," spoke Mr. Damon.

"No, it isn't that," declared the scientist. "I think I am on the
track of a great scientific discovery, and I will soon be able to make
observations that will confirm it."

"Well, I'm going to make an observation right now," said Tom, with a
laugh. "I'm going to see what there is for breakfast."

"And that reminds me," came from Mr. Jenks, "shall we move our camp,
Bill, and take the tent with us to the cave?"

"I hardly think so," was the answer. "I think the best plan would be to
conceal the tent somewhere around here, in case you might need it again.
You can also store what food you have l