Josephus Baxter seemed to have recovered some of his spirits after his narrow escape from death in the fireworks factory blaze. He greeted Tom and Ned with a smile as they entered the improvised laboratory he had been able to set up in what had once been a factory for the making of wooden ware, an industry that, for some reason, did not flourish in Shopton.

"I'm glad to see you, Mr. Swift," said the chemist, who seemed to have aged several years in the few weeks that had intervened since the fire. "I want to thank you for giving me a chance to start over again."

"Oh, that's all right," said Tom easily. "We inventors ought to help one another. Are you able to do anything here?"

"As much as possible without my secret formulae," was the answer. "If I only had those back from the rascals, Field and Melling, I would be able to go ahead faster. As it is, I am working in the dark. For some of the formulae were given to me by a Frenchman, and I had only one copy. I kept that in the safe of the fireworks concern, and after the fire it could not be found."

"Was the safe destroyed?" asked Tom.

"No. But the doors were open, and much of what had been inside was in ashes and cinders. Amos Field claimed that the explosion had blown open the safe and burned a lot of their valuable fireworks formulae too."

"And you believe they have yours?" asked Ned.

"I'm sure of it!" was the fierce answer. "Those men are unprincipled rogues! They had been at me ever since I was foolish enough to tell them about my formulae to get me to sell them a share. But I refused, for I knew the secret mixtures would make my fortune when I could establish a new dye industry. Field and Melling claimed they wanted the formulae for their fireworks, but that was only an excuse. The formulae were not nearly so valuable for pyrotechnics as for dyes. The fireworks business is not so good, either, since so many cities have voted for a 'Sane Fourth of July.'"

"I can appreciate that," said Tom. "But what we called for, Mr. Baxter, is to find if you have room enough to let me do a little experimenting here. I am working on a new kind of fire extinguisher, to be dropped on tall buildings from an airship."

"Sounds like a good idea," said the chemist, rather dreamily.

"Well, I have the airship, and I can see my way clear to perfecting a device to drop the chemicals in metal tanks or bombs," went on Tom. "But what bothers me is the chemical mixture that will put out fires better than the carbon dioxide mixtures now on the market."

"I haven't given that much study myself," said Mr. Baxter. "But you are welcome to anything I have, Mr. Swift. The whole place, such as it is, will be at your disposal at any time. I intend to have it in better shape soon, but I have to proceed slowly, as I lost nearly everything I owned in that fire. If I could only get those formulae back!" he sighed.

"Perhaps you may recall the combinations, suggested Ned. "Or can't you get them from that Frenchman?"

"He is dead," answered the chemist. "Everything seems to be against me!"

"Well, it's always darkest just before daylight," said Tom. "So let us hope for the best. We both have had a bit of bad luck. But when I think of Rad, who may lose his eyesight, I can stand my losses smiling."

"Yes," agreed Mr. Baxter, "you have big assets when you have your health and eyesight."

Three days later the eye specialist looked at Rad. Tom stood by anxiously and waited for the verdict. The doctor motioned to the young inventor to follow him out of the room, while Mrs. Baggert replaced the bandages on the colored man's eyes and Koku stood near him, sympathetically patting Rad on the back.

"Well?" asked Tom nervously, as he faced the physician.

"I am sorry, Mr. Swift, that I can not hold out much hope that your man will ever regain his sight," was the answer.

Tom could not repress a gasp of pity.

"I do not say that the case is altogether hopeless," the doctor went on; "but it would be wrong to encourage you to hope for much. I may be able to save partly the sight of one eye."

"Poor Rad!" murmured Tom. "This will break his heart."

"There is no need for telling him at once," Dr. Henderson said. "It will only make his recovery so much the slower. It will be weeks before I am able to operate, and, meanwhile, he should be kept as comfortable and cheerful as possible."

"We'll see to that," declared Tom. "Is he otherwise injured?"

"No, it is merely his eyesight that we have to fear for. And, as I said, that is not altogether hopeless, though it would not be honest to let you look for much success. I shall see him from time to time until his eyes are ready to operate on."

Tom and his friends were forced to take such comfort as they could from this verdict, but no hint of their downcast feelings were made manifest to Eradicate.

"Whut de doctor man done say, Massa Tom?" asked Eradicate when the young inventor went back into the sick room.

"Oh, he talked a lot of big Latin words, Rad--bigger words than you used to use on your mule Boomerang," and Tom forced a laugh. "All he meant was that you'd have to stay in bed a while and let Koku wait on you."

"Huh! Am dat--dat big--dat big nice man heah now?" asked Rad, feeling around with his bandaged hand; and a smile showed beneath the cloth over his eyes.

"I here right upsidedown by you, Rad," said Koku, and his big hand clasped the smaller one of the black man.

"Koku--yo'--yo' am mighty good to me," murmured Eradicate. "I reckon I been cross to yo' sometimes, but I didn't mean nuffin' by it!"

"Huh! me an' you good friends now," said the giant. "Anybody what hurt my Rad, I--I--bust 'im! Dat I do!" cried the big fellow.

"Come on," whispered Tom to Ned. "They'll get along all right together now."

But Eradicate caught the sound of his young employer's footsteps and called:

"Yo' goin', Massa Tom?"

"Yes, Rad. Is there anything you want?"

"No, Massa Tom. I jest wanted to ast if yo' done 'membered de time mah mule Boomerang got stuck in de road, an' yo' couldn't git past in yo' auto? Does yo' 'member dat?"

"Indeed I do!" laughed Tom, and Eradicate also chuckled at the recollection.

"That laugh will do him more good than medicine," declared the doctor, as he took his leave. "I'll come again, when I can make a more thorough examination," he added.

For Tom the following days, that lengthened into weeks, were anxious ones. There was a constant worry over Eradicate. Then, too, he was having trouble with his latest invention--his aerial fire-fighting apparatus. It was not that Tom was financially dependent on this invention. He was wealthy enough for his needs from other patented inventions he and his father owned.

But Tom Swift was a lad not easily satisfied. Once embarked on an enterprise, whether it was the creation of a gigantic searchlight, an electric rifle, a photo telephone or a war tank, he never rested until he had brought it to a successful consummation.

But there was something about this chemical fire extinguishing mixture that defied the young inventor's best efforts. Mixture after mixture was tried and discarded. Tom wanted something better than the usual carbonate and sulphuric combination, and he was not going to rest until he found it.

"I think you've struck a blind lead, Tom," said Ned, more than once.

"Well, I'm not going to give up," was the firm answer.

"Bless my shoe laces!" cried Mr. Damon, when he had called on Tom once at the Baxter laboratory and had been driven out, holding his breath, because of the chemical fumes, "I should think you couldn't even start a fire with that around, Tom, much less need to put one out."

"Well, it doesn't seem to work," said the young inventor ruefully. "Everything I do lately goes wrong."

"It is that way sometimes," said Mr. Baxter. "Suppose you let me study over your formulae a bit, Mr. Swift. I haven't given much thought to fire extinguishers, but I may be able, for that very reason, to approach the subject from a new angle. I'll lay aside my attempt to get back the lost formulae and help you."

"I wish you would!" exclaimed Tom eagerly. "My head is woozie from thinking! Suppose I leave you to yourself for a time, Mr. Baxter? I'll go for an airship ride."

"Yes, do," urged the chemist. "Sometimes a change of scene is of benefit. I'll see what I can do for you."

"Will you come along, Ned--Mr. Damon?" asked Tom, as he prepared to leave the improvised laboratory, the repairs on his own not yet having been finished.

"Thank you, no," answered Ned. "I have some collections to make."

"And I promised my wife I'd take her riding, Tom," said the jolly, eccentric man. "Bless my umbrella! she'd never forgive me if I went off with you. But I'll run you to your first stopping place, Ned, and you to your hangar, Tom."

His invitation was accepted, and, in due season, Tom was soaring aloft in one of his speedy cloud craft.

"Guess I'll drop down and get Mary Nestor," he decided, after riding about alone for a while and finding that the motor was running sweetly and smoothly. "She hasn't been out lately."

Tom made a landing in a field not far from the home of the girl he hoped to marry some day, and walked over to her house.

"Go for a ride? I just guess. I will!" cried Mary, with sparkling eyes. "Just wait until I get on my togs."

She had a leather suit, as had Tom, and they were soon in the machine, which, being equipped with a self-starter, did not need the services of a mechanician to whirl the propellers.

"Oh, isn't it glorious!" said Mary, as she sat at Tom's side. They were in a little enclosed cabin of the craft--which carried just two--and, thus enclosed, they could speak by raising their voices somewhat, for the noise of the motor was much muffled, due to one of Tom's inventions.

Other rides on other days followed this one, for Tom found more rest and better refreshment after his hours of toil and study in these rides with Mary than in any other way.

"I do love these rides, Tom!" the girl cried one day when the two were soaring aloft. "And this one I really believe is better than any of the rest. Though I always think that," she added, with a slight laugh.

"Glad you like it," Tom answered, and there was something in his voice that caused Mary to look curiously at him.

"What's the matter, Tom?" she asked. "Has anything happened? Is Rad's case hopeless?"

"Oh, no, not yet. Of course it isn't yet sure that he will ever see again, but, on the other hand, it isn't decided that he can't. It's a fifty-fifty proposition."

"But what makes you so serious?"

"Was I?"

"I should say so! You haven't told me one funny thing that Mr. Damon has said lately."

"Oh, haven't I? Well, let me see now," and he sent the machine up a little. "Well, the other day he--"

Tom suddenly stopped speaking and began rapidly turning several valve wheels and levers.

"What--what's the matter?" gasped Mary, but she did not clutch his arm. She knew better than that.

"The motor has stopped," Tom answered, and the girl became aware of a cessation of the subdued hum.

"Is it--does it mean danger?" she asked.

"Not necessarily so," Tom replied. "It means we have to make a forced landing, that's all. Sit tight! We're going down rather faster than usual, Mary, but we'll come out of it all right!"'