definitely adopted.

"But," said Elphinstone, "what thickness must we give it?"

"A thickness of six feet," replied Barbicane.

"You surely don't think of mounting a mass like that upon a
carriage?" asked the major.

"It would be a superb idea, though," said Maston.

"But impracticable," replied Barbicane. "No, I think of sinking
this engine in the earth alone, binding it with hoops of wrought
iron, and finally surrounding it with a thick mass of masonry of
stone and cement. The piece once cast, it must be bored with
great precision, so as to preclude any possible windage. So there
will be no loss whatever of gas, and all the expansive force of
the powder will be employed in the propulsion."

"One simple question," said Elphinstone: "is our gun to be rifled?"

"No, certainly not," replied Barbicane; "we require an enormous
initial velocity; and you are well aware that a shot quits a
rifled gun less rapidly than it does a smooth-bore."

"True," rejoined the major.

The committee here adjourned for a few minutes to tea and sandwiches.

On the discussion being renewed, "Gentlemen," said Barbicane,