Tom looked
down, and saw a dark figure standing under an apple tree.

"Hello! Who's there?" called the lad, after he had raised the sash.

"It's I--Mr. Jenks," was the surprising answer.

"Mr. Jenks?" repeated Tom.

"Yes--Barcoe Jenks, of Earthquake Island."

"You here? What do you want?"

"Can you come down?"

"What for?"

"Tom Swift, I've something very important to tell you," was the answer
in a low voice, yet which carried to Tom's ears perfectly. "Do you want
to make a fortune for yourself--and for me?"

"How?" Tom was beginning to think more and more that Mr. Jenks was
crazy.

"How? By helping me to discover the secret of Phantom Mountain, where
the diamonds are made! Will you?"

"Wait a minute--I'll come down," answered Tom, and he began to grope for
his clothes in the dim light of the little electric lamp.

What was the secret of Phantom Mountain? What did Mr. Jenks really want?
Could he make diamonds? Tom asked himself these questions as he hastily
dressed to go down to his midnight visitor.

CHAPTER III--A STRANGE STORY

"Well, Mr. Jenks," began Tom, when he had descended to the garden, and
greeted the man who had acted so strangely on Earthquake Island, "this
is rather an odd time for a visit."

"I realize that, Tom Swift," was the answer, and the lad noticed that
the man spoke much more calmly than he had that evening at the jewelry
shop. "I realize that, but I have to be cautious in my movements."

"Why?"

"Because there are enemies on my track. If they thought I was seeking
aid to discover the secret of Phantom Mountain, my life might pay the
forfeit."

"Are you in earnest, Mr. Jenks?"

"I certainly am, and, while I must apologize for awakening you at this
unseemly hour, and for the mysterious nature of my visit, if you will
let me tell my story, you will see the need of secrecy."

"Oh, I don't mind being awakened," answered Tom, good-naturedly, "but
I will be frank with you, Mr. Jenks. I hardly can believe what you have
stated to me several times--that you know how diamonds can be made."

"I can prove it to you," was the quiet answer.

"Yes, I know. For centuries men have tried to discover the secret of
transmuting base metals into gold, and how to make diamonds by chemical
means. But they have all been failures."

"All except this process--the process used at Phantom Mountain,"
insisted the queer man. "Do you want to hear my story?"

"I have no objections."

"Th