concealed; thus all imaginable precautions had been taken for
averting the first shock; and if they did get crushed, they
must, as Michel Ardan said, be made of very bad materials.

The entrance into this metallic tower was by a narrow aperture
contrived in the wall of the cone. This was hermetically closed
by a plate of aluminum, fastened internally by powerful
screw-pressure. The travelers could therefore quit their prison
at pleasure, as soon as they should reach the moon.

Light and view were given by means of four thick lenticular
glass scuttles, two pierced in the circular wall itself, the
third in the bottom, the fourth in the top. These scuttles then
were protected against the shock of departure by plates let into
solid grooves, which could easily be opened outward by
unscrewing them from the inside. Reservoirs firmly fixed
contained water and the necessary provisions; and fire
and light were procurable by means of gas, contained in a
special reservoir under a pressure of several atmospheres.
They had only to turn a tap, and for six hours the gas would
light and warm this comfortable vehicle.

There now remained only the question of air; for allowing for
the consumption of air by Barbicane, his two companions, and two
dogs which he proposed taking with him, it was necessary to
renew the air of the projectile. Now air consists principally
of twenty-one parts of oxygen and seventy-nine of nitrogen.
The lungs absorb the oxygen, which is indispensable for the support
of life, and reject the nitrogen. The air expired loses nearly
five per cent. of the former and contains nearly an equal volume