“It is possible to explode and yet be honest,” replied J.T.  Maston sententiously.

“Evidently,” answered Barbicane.  “I am, therefore, going to beg our worthy secretary to calculate the weight of a cast-iron cannon 900 feet long, with an inner diameter of nine feet, and sides six feet thick.”

“At once,” answered J.T.  Maston, and, as he had done the day before, he made his calculations with marvellous facility, and said at the end of a minute—­

“This cannon will weigh 68,040 tons.”

“And how much will that cost at two cents a pound?”

“Two million five hundred and ten thousand seven hundred and one dollars.”

J.T.  Maston, the major, and the general looked at Barbicane anxiously.

“Well, gentlemen,” said the president, “I can only repeat what I said to you yesterday, don’t be uneasy; we shall not want for money.”

Upon this assurance of its president the committee broke up, after having fixed a third meeting for the next evening.

CHAPTER IX.

THE QUESTION OF POWDERS.

The question of powder still remained to be settled.  The public awaited this last decision with anxiety.  The size of the projectile and length of the cannon being given, what would be the quantity of powder necessary to produce the impulsion?  This terrible agent, of which, however, man has made himself master, was destined to play a part in unusual proportions.

It is generally known and often asserted that gunpowder was invented in the fourteenth century by the monk Schwartz, who paid for his great discovery with his life.  But it is nearly proved now that this story must be ranked among the legends of the Middle Ages.  Gunpowder was invented by no one; it is a direct product of Greek fire, composed, like it, of sulphur and saltpetre; only since that epoch these mixtures; which were only dissolving, have been transformed into detonating mixtures.

But if learned men know perfectly the false history of gunpowder, few people are aware of its mechanical power.  Now this is necessary to be known in order to understand the importance of the question submitted to the committee.

Thus a litre of gunpowder weighs about 2 lbs.; it produces, by burning, about 400 litres of gas; this gas, liberated, and under the action of a temperature of 2,400 deg., occupies the space of 4,000 litres.  Therefore the volume of powder is to the volume of gas produced by its deflagration as 1 to 400.  The frightful force of this gas, when it is compressed into a space 4,000 times too small, may be imagined.

This is what the members of the committee knew perfectly when, the next day, they began their sitting.  Major Elphinstone opened the debate.

“My dear comrades,” said the distinguished chemist, “I am going to begin with some unexceptionable figures, which will serve as a basis for our calculation.  The 24-lb. cannon-ball, of which the Hon. J.T.  Maston spoke the day before yesterday, is driven out of the cannon by 16 lbs. of powder only.”