certain limits."

"Perfectly," said the major.

"What are the usual rules in such a case? Ordinarily the length of a
cannon is twenty or twenty-five times the diameter of the projectile,
and it weighs 235 to 240 times its weight."

"It is not enough," cried J.T. Maston with impetuosity.

"I agree to that, my worthy friend, and in fact by keeping that
proportion for a projectile nine feet wide, weighing 30,000 lbs., the
engine would only have a length of 225 feet and a weight of 7,200,000
lbs."

"That is ridiculous," resumed J.T. Maston. "You might as well take a
pistol."

"I think so too," answered Barbicane; "that is why I propose to
quadruple that length, and to construct a cannon 900 feet long."

The general and the major made some objections, but, nevertheless, this
proposition, strongly supported by the secretary, was definitely
adopted.

"Now," said Elphinstone, "what thickness must we give its sides?"

"A thickness of six feet," answered Barbicane.

"You do not think of raising such a mass upon a gun-carriage?" asked the