"Yes," answered Barbicane, "and for another reason still more
important."

"What do you mean, Barbicane?" asked the major.

"I mean that it is not enough to send up a projectile and then to think
no more about it; we must follow it in its transit."

"What?" said the general, slightly surprised at the proposition.

"Certainly," replied Barbicane, like a man who knew what he was saying,
"or our experiment will be without result."

"But then," replied the major, "you will have to give the projectile
enormous dimensions."

"No. Please grant me your attention. You know that optical instruments
have acquired great perfection; certain telescopes increase objects six
thousand, and bring the moon to within a distance of forty miles. Now at
that distance objects sixty feet square are perfectly visible. The power
of penetration of the telescope has not been increased, because that
power is only exercised to the detriment of their clearness, and the
moon, which is only a reflecting mirror, does not send a light intense
enough for the telescopes to increase objects beyond that limit."

"Very well, then, what do you mean to do?" asked the general. "Do you
intend giving a diameter of sixty feet to your projectile?"

"No."