"But if they only have the model, and you still have some of the finished appliances," asked Alice, "can't you get ahead of them yet?"

"I'm afraid not," Russ replied. "You see, the patent office doesn't require models to be filed in all cases now. You can get a patent merely on drawings. They can still get ahead of me."

"Not if you file your drawings now!" exclaimed Ruth.

"Yes, but I'm not ready. You see the machine isn't perfected yet. I am still working on it. But they can file a prior claim, and get a patent on something so near like mine that I would be refused a patent when I applied.

"You see I haven't made any formal application yet. Of course, if it came to a question of a lawsuit, I might beat them out. But I have no money to hire lawyers, and they have. The only thing for me to do is to get that model back before they have a chance to use it to make drawings from. And how to do it I don't know."

"Do you know who that messenger boy was?" asked Alice suddenly of the machinist.

"I never saw him before, Miss--no. He came in a taxicab."

"A taxicab!" cried Russ, excitedly. "You didn't say that before. Did you happen to notice the number?"

If ever Russ Dalwood was thankful it was then, and the cause of it was that Mr. Burton had a mathematical mind in which figures seemed to sprout by second nature.

"I did notice the number," he said. "It isn't often that taxicabs stop out in front here, and I looked from my window as one drew up at the curb. I was working on your patent at the time. I saw the number of the cab, later, as the messenger boy rode off in it with the model."

"What was it?" asked Russ, preparing to make a note.

The machinist gave it to him.

"Now if we can only trace it!" exclaimed the young inventor.

"I guess I can help you out, friend," broke in their own taxicab chauffeur. "I've got a list of all the cabs in New York, and the companies that run them." Rapidly he consulted a notebook, and soon had the desired information. The office of the company was not far away, and Russ and the girls were soon speeding toward it. What the next move was to be no one could say.

The manager remembered the call that had come in. Two men had come with a messenger boy to engage a cab to go to the address of the machine shop.

"And who were the two men?" asked Russ.

The manager described one whom Ruth and Alice had no difficulty in recognizing as Simp Wolley.

"The other man was shorter and not so well dressed," the cab manager went on.

"Bud Brisket!" exclaimed Russ. "I know him. Now the question is: Where did they take my model?"

"There I'm afraid I can't help you," said the manager.

"Wait!" exclaimed Alice. "Did you happen to notice the number on the messenger boy's cap?"

"No, I did not, I'm sorry to say," the man answered.

"Then that clue is no good," spoke Russ, with a sigh.

"It might be," put in Ruth. "The messenger was probably engaged from the office nearest here. We could find that and make some inquiries."

"So we could!" cried Alice. "Oh, Ruth, you're a dear!"

Russ looked as though he would have said the same thing had he dared.

An inquiry over the telephone to the main office of the messenger service, brought the desired information. And soon, in their taxicab Russ, Ruth and Alice were at the sub-station. There the ident.i.ty of the messenger was soon learned, and he was sent for.

"Sure, I went to de machine shop," admitted the snub-nosed, freckled-faced lad. "I got some sort of a thing. I didn't know what it was."

"And where did you take it?" asked Russ eagerly.

"Right where dem men told me to. Dey met me around de corner, got in de cab and rode off wid it."

"And what did you do?" asked the manager of the messenger.

"Oh, dey gave me carfare, an' a tip, and I come back here."

"But where did they go?" asked Russ.

"Off in de taxi. I didn't notice."

Russ looked hopeless, but Ruth exclaimed:

"We've got to go back to the taxi office and see the chauffeur of that car. He's the only one who can tell us where the men are."

"Good!" cried Russ. "We'll do it."

Back again they went, to find that the car had just come in, after a long trip. The chauffeur readily gave the address to which he had driven the two men, after the messenger boy had gotten out. It was in an obscure section of Jersey City.

"And there's where I'm going!" cried Russ. "Wolley and Brisket are probably going to try to work their scheme from there. But maybe I can stop them."

"I--I think we had better go home, Alice dear," said Ruth gently, at this point.

"Yes," sighed the other, "though I'd love to be there at the finish!"

"Alice!" gasped her sister.

"Well, I would," she said, defiantly.

"Maybe it wouldn't be best," suggested Russ. "I'll get a friend of mine, though. Now shall I take you home?"

"No, indeed!" cried Ruth. "That will delay you. You go right on after them. Alice and I can get home all right. It isn't late."

"It will give me pleasure if the young ladies will allow me to send them home in one of our cabs," put in the manager. "I am sorry that any of our men was used in a criminal manner."

"It wasn't your fault," spoke Russ. "But I guess the girls will be glad to be sent home. I'll keep on. I haven't any time to lose."

And while he sped off in his taxi, in pursuit of the men who were trying to cheat him out of his patent, Ruth and Alice took their places in another cab, and were driven back to the Fenmore Apartment.