icable. To
satisfy the Professor, you can theorize in something after this fashion:
If we double the number of cars, thus decreasing by one half the
distance which each has to go, we shall attain twice the speed. Each of
the sixteen cars will have but one eighth of a mile to go. At the
uniform rate we have adopted, the two miles can be done in seven and a
half instead of fifteen seconds. With thirty-two cars, and a sixteenth
of a mile, or twenty rods difference in their length, we arrive at the
speed of a mile in less than two seconds; with sixty-four cars, each
travelling but ten rods, a mile under the second. More than sixty miles
a minute! If this isn't rapid enough for the Professor, tell him to go
on, increasing the number of his cars and diminishing the distance each
one has to run. If sixty-four cars yield a speed of a mile inside the
second, let him fancy a Tachypomp of six hundred and forty cars, and
amuse himself calculating the rate of car number 640. Just whisper to
him that when he has an infinite number of cars with an infinitesimal
difference in their lengths, he will have obtained that infinite speed
for which he seems to yearn. Then demand Abscissa."

I wrung my friend's hand in silent and grateful admiration. I could say
nothing.

"You have listened to the man of theory," he said proudly. "You shall
now behold the practical engineer. We will go to the west of the
Mississippi and find some suitably level locality. We will erect thereon
a model Tachypomp. We will summon thereunto the professor, his daughter,
and why not his fair sister Jocasta, as well? We will take them a
journey which shall much astonish the venerable Surd. He shall place
Abscissa's digits in yours and bless you both with an algebraic formula.
Jocasta shall contemplate with wonder the genius of Rivarol. But we have
much to do. We must ship to St. Joseph the vast amount of material to
be employed in the construction of the Tachypomp. We must engage a small
army of workmen to effect that construction, for we are to annihilate
time and space. Perhaps you had better see your bankers."

I rushed impetuously to the door. There should be no delay.

"Stop! stop! _Um Gottes Willen_, stop!" shrieked Rivarol. "I launched my
butcher this morning and I haven't bolted the----"

But it was too late. I was upon the trap. It swung open with a crash,
and I was plunged down, down, down! I felt as if I were falling through
illimitable space. I rememb