"Right! that's correct!" he cried.

"You think so?" asked Barbican.

"As true as Euclid!" exclaimed M'Nicholl.

"Wonderful fellows," murmured the Frenchman, smiling with admiration.

"You understand now, Ardan, don't you?" asked Barbican.

"Don't I though?" exclaimed Ardan, "why my head is splitting with it!"

"Therefore," continued Barbican,

" 2 10 r 1 10 r r
2v = 2gr {1 - ----- - ---- (----- - -----) }
d 81 d d - r "

"And now," exclaimed M'Nicholl, sharpening his pencil; "in order to
obtain the velocity of the Projectile when leaving the atmosphere, we
have only to make a slight calculation."

The Captain, who before clerking on a Mississippi steamboat had been
professor of Mathematics in an Indiana university, felt quite at home at
the work. He rained figures from his pencil with a velocity that would
have made Marston stare. Page after page was filled with his
multiplications and divisions, while Barbican looked quietly on, and
Ardan impatiently stroked his head and ears to keep down a rising
head-ache.