Tom Swift was a most generous lad, but when he saw that Mr. Damon had with him Mr. Parker, the gloomy scientist, who seemed to take delight in predicting disasters, our hero's spirits were not exactly of the best. He would have much preferred not to take Mr. Parker on the quest for the diamond makers, but, since Mr. Damon had mentioned it, he did not see how he could very well refuse.

"But perhaps he won't care to go," thought Tom.

He was undeceived a moment later, however, for the scientist remarked:

I am very glad to meet you once more, Mr. Swift. I have scarcely thanked you enough for what you did for us in erecting your wireless station on Earthquake Island, which, as you recall, I predicted would sink into the sea. It did, I am glad to say, not because I like to see islands destroyed, but because science has been vindicated. Now I have just heard you remark that you are about to set off to the mountains in search of some men who are making diamonds. I need hardly state that this is utterly useless, for no diamonds, commercially valuable, can be made by men. But the trip may be valuable in that it will permit me to demonstrate some scientific facts.

"Therefore, if you will permit me, I will be very glad to accompany you and Mr. Damon. I shall be delighted, in short, and I can start as soon as you are ready."

"There's no hope for it!" thought Tom, dismally. "I suppose he'll wake up every morning, and predict that before night the world will come to an end, or he'll prophesy that the airship will blow up, and vanish, when about seven miles above the clouds. Well, there's no way out of it, so here goes."

Thereupon Tom welcomed the scientist as cordially as he could, and invited him to form one of the party that would set off in the airship to search for Phantom Mountain.

"Bless my jewelry box!" exclaimed Mr. Damon. when this formality was over. "Tell me more about it, Tom."

Which our hero did, stating the need of maintaining secrecy on account of the danger to Mr. Jenks. Mr. Damon and Mr. Parker both agreed to say nothing about the matter, and then the scientist became much interested in the Red Cloud, which he closely examined. He even complimented Tom on the skill shown in making it, and, contrary to our hero's expectation, did not predict that it would blow up the next time it was used.

"How did you happen to arrive just at this time, Mr. Damon?" asked Tom.

"It was partly due to Mr. Parker," was the answer. "I had not seen him since we were rescued from the island, until a few days ago he called on me at my home. I happened to mention that you lived near here, and suggested that he might like to see some of your inventions. He agreed, and we came over in my auto. And now, bless my liver-pin! I find you about to start off on another trip."

"And have you fully decided to go with me?" asked Tom. "There may be danger, and I don't like the way that mysterious man behaved."

"Oh, bless my revolver!" cried Mr. Damon. "I'm used to danger by this time. Of course I'm going, and so is Mr. Parker. Do you know," and the man, who was always blessing something, came closer to the lad, and whispered: "Do you know, Tom, Mr. Parker is a very peculiar individual."

"I'm sure of it," answered the young inventor, looking at the gentleman in question, who was then inside the airship cabin.

"But he's all right, even if he is predicting unpleasant things," went on Mr. Damon. "I think we'll get better acquainted with him after a bit."

"I hope so," agreed Tom, but he did not realize then how close his companionship with Mr. Parker was to be, nor what dangers they were to share later.

The friends talked at considerable length of the prospective trip, and Tom, by this time, had ascertained what needed to be done to the airship to get it in shape to travel. It would take about a week, and, in the meanwhile, Mr. Damon would go home and get his affairs in order for the voyage. Tom's father was introduced to Mr. Parker, and, the former, finding that the scientist held some views in common with him, invited the gloomy predictor to remain at the Swift home until the Red Cloud was ready to sail. Tom could not repress a groan at this, but he decided he would have to make the best of it.

Mr. Damon left for home that afternoon, promising to be on hand at the time set to start for Phantom Mountain.

Tom was up waiting for Mr. Jenks at twelve o'clock that night. Shortly after the hour he saw a dark figure steal into the orchard. At first he feared lest it might be one of the spies who were, he was now convinced, on the trail of the man who was seeking to discover the secret of the diamond makers. But a whistle, which came to the lad's ear a moment later (that being a signal Mr. Jenks had agreed to sound), told Tom that it was none other than the visitor he expected.

"All right, Mr. Jenks, I'm here," called Tom, cautiously. "Come over this way," and he went out from the shadow of the house, where he had been waiting, and met the men. "We'll go into my private work-shop," the youth added, leading the way.

"Have you decided to go with me?" asked Mr. Jenks, in an anxious whisper. "Did you find the diamonds to be real ones?"

"I did; and I'm going," spoke Tom.

"Good! That relieves my mind. But we are still in danger. I was followed by my shadower to-day, and only succeeded in shaking him off just before coming here. I don't believe he knows what I am about to do."

"Oh, yes he does," said Tom.

"He does? How?"

"Because he was here, and warned me against you!"

"You don't mean it! Well, they are getting desperate! We must be on our guard. What sort of a man was he?"

Tom described the fellow, and Mr. Jenks stated that this tallied with the appearance of the person who had been shadowing him.

"But we'll fool them yet!" cried Tom, who had now fully entered into the spirit of the affair. "If they can follow us in the Red Cloud they're welcome to. I think we'll get ahead of them."

He then told of Mr. Damon and Mr. Parker, and Mr. Jenks agreed that it would add to the strength of the party to take these two gentlemen along.

"Though I can't say I care so much for Mr. Parker," he added. "But now as to ways and means. When can we start?"

Thereupon he and Tom talked over details in the seclusion of the little office, and arranged to leave Shopton in about a week. In the meanwhile the airship would be overhauled, stocked with supplies and provisions, and be made ready for a swift dash to the mountains.

"And now I must be going," said Mr. Jenks. "I have a great deal to do before I can start on this trip, and I hope I am not prevented by any of those men who seem to be trailing me."

"How could they prevent you?" Tom wanted to know.

"Oh, there are any number of ways," was the answer. "But I'm glad you found that my diamonds were real. We'll soon have plenty, if all goes well."

As Mr. Jenks left the shop, he started back, in some alarm.

"What's the matter?" asked Tom.

"Over there--I thought I saw a figure sneaking along under the trees--that man--perhaps--"

"That's Eradicate, our colored helper," replied Tom, with a laugh. "I posted him there to see that no strangers came into the orchard. Everything all right, Rad?" he asked, raising his voice.

"Yais, sah, Massa Tom. Nobody been around yeah this night."

"That's good. You can go to bed now," and Eradicate, yawning loudly, went to his shack. A little later Tom sought his own room, Mr. Jenks having hurried off to town, where he was boarding.

The next few days saw Tom busily engaged on the airship, making some changes and a few repairs that were needed. His father, Eradicate and Mr. Jackson helped him. As for Mr. Parker, the scientist, he went about the place, being much interested in the various machines which Tom or Mr. Swift had patented.

At other times the scientist would stroll about the extensive grounds, making what he said were "observations." One afternoon Tom saw him, apparently much excited, kneeling down back of a shed, with his ear to the ground.

"What is the matter?" asked the lad, thinking perhaps Mr. Parker might be ill.

"Have you ever had any earthquakes here, Tom Swift?" asked the scientist, quietly.

"Earthquakes? No. We had enough of them on the island."

"And you are going to have one here, in about two minutes!" cried Mr. Parker. "I predict that this place will be shaken by a tremendous shock very soon. We had all better get away from the vicinity of buildings."

"What makes you think there will be an earthquake?" asked Tom.

"Because I can hear the rumbling beneath the ground at this very minute. It is increasing in volume, showing that the tremors are working this way. There will soon be a great subterranean upheaval! Listen for yourself."

Tom cast himself down on the grass. Placing his ear close to the ground he did hear a series of dull thuds. He arose, not a little alarmed. There had never been any earthquakes in Shopton, yet he had great respect for Mr. Parker's scientific attainments.

Just then Eradicate Sampson came along. He saw Tom and Mr. Parker lying flat on the ground, and surprise showed on his honest, black face.

"Fo' de land sakes!" cried Eradicate. "What am de mattah now, Massa Tom?"

"Earthquake coming," answered Tom, briefly. "Better get away from the buildings, Rad. They might fall!" Tom's face showed the alarm he felt. What would happen to all of his valuable machinesÄto the Red Cloud?

"Earthquake?" murmured Eradicate, and he, too, cast himself down to listen. A moment later he arose with a laugh.

"What's the matter?" cried Tom.

"Why, dat ain't no earthquake!" declared the colored man.

"No. Then perhaps you know what it is," said Mr. Parker, somewhat sharply.

"Course I knows what it am," answered Eradicate, with dignity. "Dat noise am my mule Boomerang, kickin' in his stable, on account oh me not feedin' him yet. Dat's what it am. I'se gwine right now t' gib him his oats, and den yo' see dat de noise stop. Boomerang allers kick dat way when he's hungry. I show yo'!"

And, sure enough, when Eradicate had gone to the mule's stable, which was near where Mr. Parker had heard the mysterious sounds, they immediately ceased.

"Dat mule was all de earthquake dere was around here," said the colored man as he came out.

Mr. Parker walked away, saying nothing, and Tom did not make any comments--just then.