are heated by gliding over the atmospheric layers. Now, if
they enter the atmosphere, they pass at least within forty
miles of the earth, but they seldom fall upon it. The same with
our projectile. It may approach very near to the moon, and not
yet fall upon it.”
“But then,” asked Michel, “I shall be curious to know how our
erring vehicle will act in space?”
“I see but two hypotheses,” replied Barbicane, after some
moments’ reflection.
“What are they?”
“The projectile has the choice between two mathematical curves,
and it will follow one or the other according to the speed with
which it is animated, and which at this moment I cannot estimate.”
“Yes,” said Nicholl, “it will follow either a parabola or
a hyperbola.”
“Just so,” replied Barbicane. “With a certain speed it will
assume the parabola, and with a greater the hyperbola.”
“I like those grand words,” exclaimed Michel Ardan; “one knows
directly what they mean. And pray what is your parabola, if
you please?”
“My friend,” answered the captain, “the parabola is a curve of
the second order, the result of the section of a cone
intersected by a plane parallel to one of the sides.”
“Ah! ah!” said Michel, in a satisfied tone.
“It is very nearly,” continued Nicholl, “the course described by
a bomb launched from a mortar.”
“Perfect! And the hyperbola?”
“The hyperbola, Michel, is a curve of the second order, produced
by the intersection of a conic surface and a plane parallel to
its axis, and constitutes two branches separated one from the other,
both tending indefinitely in the two directions.”
“Is it possible!” exclaimed Michel Ardan in a serious tone, as
if they had told him of some serious event. “What I particularly
like in your definition of the hyperbola (I was going to say
hyperblague) is that it is still more obscure than the word you
pretend to define.”
Nicholl and Barbicane cared little for Michel Ardan’s fun.
They were deep in a scientific discussion. What curve would
the projectile follow? was their hobby. One maintained the
hyperbola, the other the parabola. They gave each other reasons
bristling with _x_. Their arguments were couched in language
which made Michel jump. The discussion was hot, and neither
would give up his chosen curve to his adversary.
This scientific dispute lasted so long that it made Michel
very impatient.
“Now, gentlemen cosines, will you cease to throw parabolas and
hyperbolas at each other’s heads? I want to understand the only
interesting question in the whole affair. We shall follow one
or the other of these curves? Good. But where will they lead
us to?”
“Nowhere,” replied Nicholl.
“How, nowhere?”
“Evidently,” said Barbicane, “they are open curves, which may be
prolonged indefinitely.”
“Ah, savants!” cried Michel; “and what are either the one or the
other to us from the moment we know that they equally lead us
into infinite space?”
Barbicane and Nicholl could not forbear smiling. They had just
been creating “art for art’s sake.” Never had so idle a question
been raised at such an inopportune moment. The sinister truth
remained that, whether hyperbolically or parabolically borne away,
the projectile would never again meet either the earth or the moon.
What would become of these bold travelers in the immediate future?
If they did not die of hunger, if they did not die of thirst,
in some days, when the gas failed, they would die from want of air,
unless the cold had killed them first. Still, important as it was
to economize the gas, the excessive lowness of the surrounding
temperature obliged them to consume a certain quantity.
Strictly speaking, they could do without its _light_, but not
without its _heat_. Fortunately the caloric generated by Reiset’s
and Regnaut’s apparatus raised the temperature of the interior
of the projectile a little, and without much expenditure they
were able to keep it bearable.
But observations had now become very difficult. the dampness of
the projectile was condensed on the windows and congealed immediately.
This cloudiness had to be dispersed continually. In any case
they might hope to be able to discover some phenomena of the
highest interest.
But up to this time the disc remained dumb and dark. It did not