"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 a.s.sets 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, Ma.s.sa 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', Ma.s.sa Tom?"

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

"No, Ma.s.sa 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 m.u.f.fled, 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.