I thought we had a sort of dinner engagement at my apartment, Bob."

"By gollies I forgot, Dutch. I'll be right over—before it gets cold."

Then immediately I turned the knob to the Municipal Aerial-car yards, and ordered my motor, as I grabbed my hat and hurried to the roof. In due time, of course, I sprang the big surprise of the evening, adding:

"And, of course, I'm going by the Tube, I feel sort of a half-partnership in it because you were one of the designers."

A curious half-pained look crossed his face. We had finished our meal, and were smoking with pushed-back chairs. He finished filling his pipe, and scowled.

"Well? Why don't you say something? Thought you'd be—well, sort of pleased."

He struck his automatic lighter and drew in a long puff of smoke before answering.

"Wish you'd take another route, Bob."

"Take another route?"

"Yes. If you want it straight, the Tube is not safe."

"You are joking."

But as I looked into his cold, thoughtful blue eyes, I knew he had never been more serious.

"I wish that you would go by the Trans-Atlantic Air Liners. They are just as fast."

"But you used to be so enthusiastic about the Tube, Dutch! Why I remember when it was being drilled that you would call me up at all kinds of wild hours to tell me the latest bits of news."

He nodded slowly.

"Yes, that was in the days before the crack."

"Yet you expected to take care of possible leaks, you know," I countered.

"But this crack opened after the tunnel had been dug past it, and lately it has opened more."

"Are the other engineers alarmed?"

"No. We are easily taking care of the extra water and again the opening seems to remain at a stationary width as it has for the past three years. But we cannot caulk it."

"Are you going to publish these views?"

"No. I made out a minority report. I can do no more."

"Dutch, you are becoming over-cautious. First sign of old age."

"Perhaps," with the old smile.

"But after all it is now more than three years since we have had a talk on the Tube. After it began to function as well as the Air-Express you sort of lost interest in it."

"And the world did too."

"Certainly—but the public ever was a fickle mistress. Who said that before me?"

He laughed and blew out a long puff of smoke.

"Everyone, Bob."

"But as to the Tube, if I cross under the sea, I would want to be as well informed on the road as I was three years ago. Now in the meantime, you have dropped interest in the long tunnel while I have become more interested in textiles—with the result that I have forgotten all I ever did know—which compared to your grasp of the details, was little enough."

But his face showed none of the old-time animation on the subject. What a different man, I mused to myself, from that enthusiastic engineering student that I used to come upon dreaming over his blue-prints. He was considered "half-cracked" in those days when he would enthuse over his undersea railroad, but his animated face was lit with inspiration. Now the light was gone.

"Well, Dutch, how about it? Aren't you going to make me that brief little sketch of the length plan and cross-section of the Tube? I remember your sketch of it in college, and it tends to confuse me with the real changes that were made necessary when the wind-propulsion method was adopted."

"All right, old timer. You remember that the Tube was widened at the sides in order that we could make two circular tubes side by side—one going each way."

"I had forgotten that they were circular."

"That is because of the pressure. A circle presents the best resistance," and picking an odd envelope from his pocket, he made the following sketch and passed it to me.

public@vhost@g@gutenberg@html@files@27609@27609-h@images@003.png" alt="CROSS-SECTION OF TUBE" title=""