"As I understand it," she said, "the projectile is really a number of shells, telescoping, one within another. I've forgotten how many there are."
"Fifty. The idea, of course, is that the original charge of powder within the cannon will send the projectile at something like two miles a second. Upon reaching a certain point in space another charge will be automatically fired in the base of the outermost shell. Thus it will act as another cannon, from which the remaining shells will be shot. And so on, until the forty-ninth shell has been blown to the rear. The remaining one will, by that time, have traveled far enough to get out of our gravitation into Alma's."
"What is the size of the fiftieth shell?"
"Only two feet in diameter; [Footnote: All dimensions are necessarily a matter of judgment; but they represent the opinion of an architect, whose sense of proportion is presumably better than average.] but of such length that it will hold five tons of explosive. It is expected to demolish a square mile of their roof."
The great projectile was carefully lowered until its tip was flush with the volcano-like mouth of the cannon. The proceeding took a long time; and it was well toward the end of the work that Powart's handsome yacht swept into the space provided for it in the circle of spectators. By prearrangement this space was next to that occupied by Mona and Fort.
As soon as the yacht had come to a stop its thrumming wings keeping it as steadily suspended in mid air as any of the lighter craft roundabout, Powart himself stepped out upon the tiny bridge. It was the signal for a great outburst of applause, in which Fort joined as heartily as any one.
"You don't seem at all envious of Mr. Powart," commented Mona, watching the athlete curiously.
He looked around as though surprised, and protested:
"On the contrary, I am really proud of his success. You see, it's this way, Mona: If he fails, then I fail too!"
And before she could ask what he meant he raised his voice enough for the dictator to hear: