as for you, Sir
Reginald, I must ask you to stand on the deck just outside the
pilothouse, to see that the electric lamp on the top of it does not come
into collision with the roof-timbers, and so drag the roof off the shed.
But as it is necessary that you should all become acquainted with the
working of the ship, you had better be with me in the pilot-house until
we are actually ready to move."

"Now," continued the professor when the quartette had made their way to
the upper floor of the pilot-house, which was moderately illuminated by
an electric lamp of small power, "the first thing to be done is to place
the tiller of the ship in a horizontal position, and thus bring into
action the automatic balancing gear. So! It is done. The next thing
is to expel the air from the entire hull of the ship, excepting, of
course, the comparatively insignificant portion reserved for habitation,
and this I do by injecting vapour into the several compartments. The
vapour drives out the air, and then, condensing like steam, creates, if
required, a perfect vacuum. This large wheel controls the valve which
we now want to open. I turn it this way, so--and now we shall see what
will happen."

Two large dials were attached to the side of the pilothouse, close
together; and upon these the professor now intently fixed his gaze. The
index-hands of both were seen to be moving. A period of perhaps half a
minute elapsed, and then the professor, suddenly shutting off the
vapour, went over and closely inspected both dials.

"Good!" he exclaimed, after a single keen glance at each of them.
"Gentlemen, let us congratulate each other. Our experiment is a SIGNAL
SUCCESS!"

"How do you know that, professor? How can you tell?" eagerly asked his
companions.

"Look at these two dials; they will tell you," replied the professor.
"This dial," tapping one with his finger, "indicates the weight of the
ship, or the pressure with which she bears upon the ground. This one,"
indicating the other, "shows the pressure of air inside the hull of the
ship. The first, as you see, shows that the ship is now pressing upon
the ground with a force of less than a single ton--in other words, she
now weighs less than one ton. The air-gauge shows that there is still
an air pressure of six pounds per square inch inside the hull, and we
therefore have, as I expected we should, a large margin of buoyancy.
Now, lieutenant, do me the favour to turn on the vapour o