"Not so simple as a simpleton," replied the Frenchman.

"The Captain merely means," said Barbican, "that at the instant the
Projectile quitted the terrestrial atmosphere it had already lost a
third of its initial velocity."

"So much as a third?"

"Yes, by friction against the atmospheric layers: the quicker its
motion, the greater resistance it encountered."

"That of course I admit, but your _v_ squared and your _v_ prime squared
rattle in my head like nails in a box!"

"The usual effect of Algebra on one who is a stranger to it; to finish
you, our next step is to express numerically the value of these several
symbols. Now some of them are already known, and some are to be
calculated."

"Hand the latter over to me," said the Captain.

"First," continued Barbican: "_r_, the Earth's radius is, in the
latitude of Florida, about 3,921 miles. _d_, the distance from the
centre of the Earth to the centre of the Moon is 56 terrestrial radii,
which the Captain calculates to be...?"

"To be," cried M'Nicholl working rapidly with his pencil, "219,572
miles, the moment the Moon is in her _perigee_, or nearest point to the
Earth."