there was some fault in all of them but this last one."

"Tell us about the others first," said Ned.

"I'll show you one of them," said Phaeton, and he drew from his pocket a small sheet of paper, which he unfolded.

"This," said he, "represents the city of New York. A is some place far up-town where people live; B is the Battery, which is down-town where they do the business. I suppose you both know what a mortar is?"

"A cannon as big around as it is long," said Ned.

"And shoots bomb-shells," said I.

"That's it," said Phaeton. "Now here, you see, is a big mortar up-town; only, instead of shooting a bomb-shell, it shoots a car. This car has no wheels, and has a big knob of India-rubber on the end for a buffer. When you get it full of people, you lock it up tight and touch off the mortar. This dotted mark represents what is called the line of flight. You see, it comes down into another sort of mortar, which has a big coiled spring inside, to stop it easy and prevent it from smashing. Then the depot-master puts up a long step-ladder and lets the people out."

Ned said he should like to be the one to touch off the mortar.

"And why wasn't that a good plan?" said I.

"There are some serious objections to it," said Phaeton, in a knowing way. "For instance, you can't aim such a thing very true when the wind is blowing hard, and people might not like to ride in it on a windy day. Besides, some people have a very strong prejudice, you know, against any sort of fire-arms."

"There wouldn't be much chance for a boy to catch a ride on it," said Ned, as if that were the most serious objection of all. "But tell us about the real invention."

"The real invention," said Phaeton, "is this," and he took up the little frame we had seen him making. Taking an India-rubber string from his pocket, he stretched it from one of the little posts to the other, and fastened it.

"Now," said he, "suppose there was a fly that lived up at this end, and had his office down at that end. He gets his breakfast, and takes his seat right here," and he laid his finger on the string, near one of the posts. "I call out, 'All aboard!' and then——"

Here Phaeton, who had his knife in his hand, cut the string in two behind the imaginary fly.

"Where is the fly now?" said he. "At his office doing business—"

"I don't understand," said Ned.

"I've only half explained it," said Phaeton. "Now, you see, it's easy enough to make a tunnel under-ground and run cars through. But a tunnel always gets full of smoke when a train goes through, which is very disagreeable, and if you send a train every fifteen minutes, all the passengers would choke. So, you see, there must be something instead of an engine and a train of cars. I propose to dig a good tunnel wherever the road wants to go, and make it as long as you please. Right through the centre I pass an India-rubber cable as large as a man's leg, and stretch it tight and fasten it to great posts at each end. All the men and boys who want to go sit on at one end, as if on horseback. When everything is ready, the train-despatcher takes a sharp axe, and with one blow clips the cable in two behind them, and zip they go to the other end before you can say Jack Robinson."

Ned said he should like to be train-despatcher.

"They'd all have to hang on like time," said I.

"Of course they would," said Phaeton; "but there are little straps for them to take hold by."

"And would there be a tub at the other end," said Ned "to catch the passengers that were broken to pieces against the end wall?"

"Oh, pshaw!" said Phaeton. "Don't you suppose I have provided for that?"

The fact was, Phaeton had spent more study on the question of landing his passengers safely than on any other part of his invention. It was not the first instance since the days of the hand-mill that made the sea salt, in which it had been found easy to set a thing going, but difficult to stop it.

"There are several ways," said he, continuing his explanation, "to let the passengers off safely. I haven't decided yet what I'll adopt. One way is, to have a sort of brake to squeeze down on the cable and make it stop gradually. I don't exactly like that, because it would wear out the cable, and these cables are going to cost a great deal of money. Another way is, to throw them against a big, soft mattress, like pins in a bowling-alley. But even that would hurt a little, I guess, no matter how soft you made the mattress. The best way is, to have it drop them in a tank of water."

"What! and get all wet?" said Ned.

"Don't be in a hurry," said Phaeton. "Each one would wear an India-rubber water-proof garment (a sort of over-dress), covering him all over and fastened up tight. Of course, these would be provided by the company."

"But wouldn't it use up a cable every time you cut it?" said Ned.

"Not at all; it could be stretched again by hitching a team of horses to the end and drawing it back, and then we should solder it together with melted India-rubber. Probably a dozen teams would be at work at night stretching cables for use next day. You see, we should have as many cables as the business of the road required."

I have never known whether Phaeton was sincere in all this, or whether he was simply fooling Ned and me. I have since suspected that he had a purpose which did not appear at the time. At any rate, we took it all in and believed it all, and looked upon him as one of the world's great inventors.

"And what do you want the ten dollars for?" said Ned.

"Well, you know nothing can be done without more or less money," said Phaeton. "The first thing is, to get up a model to send to the Patent-Office, and get a patent on it."

"What's that?" said Ned.

"What's what?"

"A model."

"A model," said Phaeton, "is a little one, with tunnel and all complete, to show how it works."

"But a tunnel," said Ned, "is a hole in the ground. You can't send a hole in the ground to the Patent-Office, no matter how small you make it."

"Oh, pshaw! Don't you understand? There would be a little wooden tube or shell, painted red, to represent the brick-work that the real tunnel would be arched in with."

"Well, what then?"

"I suppose it would cost about ten dollars to get up a model. If it's going to the Patent-Office it doesn't want to be botched up with a pocket-knife."

"Of course not," said Ned. "But the model will be only a beginning. It will take a great deal more money than that to build the real thing."

"Now you talk business," said Phaeton. "And I'm ready to talk with you. I've thought it all out. I got an idea from the way that Father says Mr. Drake manages to build so many houses."

"Let's hear about it."

"There are two ways to get the thing into operation. One is, to try it first in this town. You know we boys could dig the tunnel ourselves, and it wouldn't cost anything."

"Yes, I suppose so—if enough boys would take hold."

"Then we could give a mortgage on the tunnel, and so raise money to buy the cable, and there you are."

"That's all very fine," said Ned; "but they foreclose mortgages. And if there was a mortgage on our tunnel, and they foreclosed it while we were in there, what would become of us? How should we ever get out?"

Phaeton laughed.

"I'll tell you how we'll fix it," said he. "We'll have a secret shaft leading out of the tunnel, and not let the man we give the mortgage to know anything about it."

Ned didn't exactly know whether he was being quizzed or not.

"What's the other way of getting the thing into operation?" said he.

"The other way," said Phaeton, "is to go