“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.

I nodded as I recognized the cross-section.

“Now the plan of the thing is like this,” he added, putting aside his
pipe and pulling a sheet of paper from the corner of his desk.

Rapidly, with all his old accuracy, he sketched the main plan and leaned
over as he handed it to me.

“You see,” he explained, picking up his pipe again, “both pumps work at
one time–in fact, I should say all four, because this plan is
duplicated on the English side. On both ends then, a train is gently
pushed in by an electric locomotive. A car at a time goes through the
gate so that there is a cushion of air between each car. The same thing
happens at Liverpool. Now, when the due train comes out of the suction
tube, it goes on out the gate, but the air behind it travels right on
around and comes in behind the train that is leaving.”

“But how are you assured that it will not stall somewhere?”

“It won’t be likely to with pressure pumps going behind it and suction
pumps pulling from in front. We can always put extra power on if
necessary. Thus far the road has worked perfectly.”

“How much power do you need to send it through, under normal
conditions?”

“Our trains have been averaging about fifty tons, and for that weight we
have found that a pound pressure is quite sufficient. Now, taking the
tunnel’s length as four thousand miles (of course it is not that long,
but round figures are most convenient) and the tube width eleven and one
quarter feet each and working this out we have 3,020,000 cubic feet of
free air per minute or 2,904,000 cubic feet of compressed air, which
would use about 70,000 horse power on the air compressor.”

“But isn’t the speed rather dizzy?”

“Not any more dizzy, Bob, than those old fashioned money-carrying
machines that the department stores used to use–that is in comparison
to size. The average speed is about 360 feet a second. Of course, the
train is allowed to slow down toward the end of its run, even before it
hits the braking machinery beyond the gate.”

“But how much pressure did you say would be put on the back of the
diaphragm–I remember that each car has a flat disc on the back that
fits fairly tightly to the tube …”

“The pressure on the back is less than seven tons. However, the disc
does not fit tight. There are several leaks. For instance, the cars are
as you know, run on the principle of the monorail with a guiding rail on
each side. The grooves for the rails with their three rollers are in
each car. There is a slight leakage of air here.”

“You used the turbo type of blower, didn’t you?”

“Had to because of the noise. We put some silencing devices on that and
yet we could not kill all of the racket. However a new invention has
come up that we will make use of soon now.”

* * * * *

“But I can’t understand, Dutch, why you seemed so put out when I
announced my intention of going to Europe via the Tube. Why, I can
remember the day when that would have tickled you to death.”

“You followed the digging of the Tube, didn’t you?”

“Yes, of course.”

“You remember the volcano and lava seams?”

“Yes.”

“Well, I do not believe that the crack was a pressure crevice. If it had
been, we were far enough below the ocean floor to have partly relieved
the situation by the unusually solid building of the Tube. The
tremendous shell of this new type of specially hardened metal–“

“And the rich concrete that was used as filling! That was one job no one
slipped up on. I remember how you watched it–“

“Yet the crack has widened, Bob, since the Tube was completed.”

“How can you be certain?”

“By the amount of water coming through the drain pipes.”

“But you said that once more it was stationary.”

“Yes, and that is the very thing that proves, I believe, the nature of
the crack.”

“I don’t follow you.”

“Why it isn’t a crack at all, Bob. It is an earthquake fault.”

“Good heavens, you don’t mean–“

“Yes, I do. I mean that the next time the land slips our little tube
will be twisted up like a piece of string, or crushed like an eggshell.
That always was a rocky bit of land. I thought in going that far north,
though, that we had missed the main line of activity; I mean the
disturbances that had once wiped out a whole nation, if your scientists
are correct.”

“Then you mean that it is only a matter of time?”

“Yes, and I have been informed by one expert that the old volcanic
activity is not dead either.”

“So that is what has stolen away your laugh?”

“Well I am one of the engineers–and they won’t suspend the service.”

“Fate has played an ugly trick on you, Dutch, and through your own
dreams too. However, you have made me decide to go by the Tube.”

He took his pipe out of his mouth and stared at me.

“Sooner or later the Tube will be through, and I have never been across.
Nothing risked–a dull life. Mine has been altogether too dull. I am now
most certainly going by the Tube.”

A bit of the old fire lit up his eyes.

“Same old Bob,” he grunted as I rose, and then he grasped my hand with a
grin.

“Good luck, my boy, on your journey, and may old Vulcan be out on a
vacation when you pass his door.”

Thus we said good-by. I did not know then that I would never see him
again–that he also took the train that night in order to make one last
plea to the International Committee, and so laid down his life with the
passengers for whom he had pleaded.

It was with many conflicting thoughts, however, that I hurried to the
great Terminus that fatal night, where after being ticketed,
photographed and tabulated by an efficient army of clerks, I found
myself in due time, being ushered to my car of the train.

* * * * *