hick crust of obstinacy, which would not be easy to remove.

On his part, Robur did not seem to notice anything particular, and
coolly continued the conversation which he had begun two hours before.

"Gentlemen," said he, "you ask yourselves doubtless if this
apparatus, so marvelously adapted for aerial locomotion, is
susceptible of receiving greater speed. It is not worth while to
conquer space if we cannot devour it. I wanted the air to be a solid
support to me, and it is. I saw that to struggle against the wind I
must be stronger than the wind, and I am. I had no need of sails to
drive me, nor oars nor wheels to push me, nor rails to give me a
faster road. Air is what I wanted, that was all. Air surrounds me as
it surrounds the submarine boat, and in it my propellers act like the
screws of a steamer. That is how I solved the problem of aviation.
That is what a balloon will never do, nor will any machine that is
lighter than air."

Silence, absolute, on the part of the colleagues, which did not for a
moment disconcert the engineer. He contented himself with a
half-smile, and continued in his interrogative style, "Perhaps you
ask if to this power of the "Albatross" to move horizontally there is
added an equal power of vertical movement--in a word, if, when, we
visit the higher zones of the atmosphere, we can compete with an
aerostat? Well, I should not advise you to enter the "Go-Ahead"
against her!"

The two colleagues shrugged their shoulders. That was probably what
the engineer was waiting for.

Robur made a sign. The propelling screws immediately stopped, and
after running for a mile the "Albatross" pulled up motionless.

At a second gesture from Robur the suspensory helices revolved at a
speed that can only be compared to that of a siren in acoustical
experiments. Their f-r-r-r-r rose nearly an octave in the scale of
sound, diminishing gradually in intensity as the air became more
rarified, and the machine rose vertically, like a lark singing his
song in space.

"Master! Master!" shouted Frycollin. "See that it doesn't break!"

A smile of disdain was Robur's only reply. In a few minutes the
"Albatross" had attained the height of 8,700 feet, and extended the
range of vision by seventy miles, the barometer having fallen 480
millimeters.

Then the "Albatross" descended. The diminution of the pressure in
high altitudes leads to the diminution of oxygen in the air, and
consequently in the blood. This has be