The projectile was to be filled to the depth of three feet with water destined to support a water-tight wooden disc, which easily worked within the walls of the projectile.  It was upon this raft that the travellers were to take their place.  As to the liquid mass, it was divided by horizontal partitions which the departing shock would successively break; then each sheet of water, from the lowest to the highest, escaping by valves in the upper part of the projectile, thus making a spring, and the disc, itself furnished with extremely powerful buffers, could not strike the bottom until it had successively broken the different partitions.  The travellers would doubtless feel a violent recoil after the complete escape of the liquid mass, but the first shock would be almost entirely deadened by so powerful a spring.

It is true that three feet on a surface of 541 square feet would weigh nearly 11,500 lbs; but the escape of gas accumulated in the Columbiad would suffice, Barbicane thought to conquer that increase of weight; besides, the shock would send out all that water in less than a second, and the projectile would soon regain its normal weight.

This is what the president of the Gun Club had imagined, and how he thought he had solved the great question of the recoil.  This work, intelligently comprehended by the engineers of the Breadwill firm, was marvellously executed; the effect once produced and the water gone, the travellers could easily get rid of the broken partitions and take away the mobile disc that bore them at the moment of departure.

As to the upper sides of the projectile, they were lined with a thick wadding of leather, put upon the best steel springs as supple as watch-springs.  The escape-pipes hidden under this wadding were not even seen.

All imaginable precautions for deadening the first shock having been taken, Michel Ardan said they must be made of “very bad stuff” to be crushed.

The projectile outside was nine feet wide and twelve feet high.  In order not to pass the weight assigned the sides had been made a little less thick and the bottom thicker, as it would have to support all the violence of the gases developed by the deflagration of the pyroxyle.  Bombs and cylindro-conical howitzers are always made with thicker bottoms.

The entrance to this tower of metal was a narrow opening in the wall of the cone, like the “man-hole” of steam boilers.  It closed hermetically by means of an aluminium plate fastened inside by powerful screw pressure.  The travellers could therefore leave their mobile prison at will as soon as they had reached the Queen of Night.

But going was not everything; it was necessary to see on the road.  Nothing was easier.  In fact, under the wadding were four thick lenticular footlights, two let into the circular wall of the projectile, the third in its lower part, and the fourth in its cone.  The travellers could, therefore, observe during their journey the earth they were leaving, the moon they were approaching, and the constellated spaces of the sky.  These skylights were protected against the shocks of departure by plates let into solid grooves, which it was easy to move by unscrewing them.  By that means the air contained in the projectile could not escape, and it was possible to make observations.