It is probable that we shall have to give it gigantic dimensions, but, however great our difficulties might be, our industrial genius will easily overcome them.

Will you please listen to me and spare objections for the present?
I do not fear them." An approving murmur greeted this declaration.
"We must not forget," resumed Barbicane, "to what point our yesterday's debate brought us; the problem is now the following: how to give an initial speed of 12,000 yards a second to a shot 108 inches in diameter weighing 20,000 lbs.
"That is the problem indeed," answered Major Elphinstone.
"When a projectile is hurled into space," resumed Barbicane, "what happens?
It is acted upon by three independent forces, the resistance of the medium, the attraction of the earth, and the force of impulsion with which it is animated.

Let us examine these three forces.

The resistance of the medium--that is to say, the resistance of the air--is of little importance.

In fact, the terrestrial atmosphere is only forty miles deep.