the same. Consider
me most deplorably ignorant on the nature of these curves."

"Well," said the Captain, a little bumptiously, "a parabola is a curve
of the second order, formed by the intersection of a cone by a plane
parallel to one of its sides."

"You don't say so!" cried Ardan, with mouth agape. "Do tell!"

"It is pretty nearly the path taken by a shell shot from a mortar."

"Well now!" observed Ardan, apparently much surprised; "who'd have
thought it? Now for the high--high--bully old curve!"

"The hyperbola," continued the Captain, not minding Ardan's antics, "the
hyperbola is a curve of the second order, formed from the intersection
of a cone by a plane parallel to its axis, or rather parallel to its two
_generatrices_, constituting two separate branches, extending
indefinitely in both directions."

"Oh, what an accomplished scientist I'm going to turn out, if only left
long enough at your feet, illustrious _maestro_!" cried Ardan, with
effusion. "Only figure it to yourselves, boys; before the Captain's
lucid explanations, I fully expected to hear something about the high
curves and the low curves in the back of an Ancient Thomas! Oh, Michael,
Michael, why didn't you know the Captain earlier?"

But the Captain was now too deeply interested in a hot discussion with
Barbican to notice that the Frenchman was only funning him. Which of the
two curves had been the one most probably taken by the Projectile?
Barbican maintained it was the parabolic; M'Nicholl insisted that it was
the hyperbolic. Their tempers were not improved by the severe cold, and
both became rather excited in the dispute. They drew so many lines on
the table, and crossed them so often with others, that nothing was left
at last but a great blot. They covered bits of paper with _x_'s and
_y_'s, which they read out like so many classic passages, shouting them,
declaiming them, drawing attention to the strong points by gesticulation
so forcible and voice so loud that neither of the disputants could hear
a word that the other said. Possibly the very great difference in
temperature between the external air in contact with their skin and the
blood coursing through their veins, had given rise to magnetic currents
as potential in their effects as a superabundant supply of oxygen. At
all events, the language they soon began to employ in the enforcement of
their arguments fairly made the Frenchman's hair stand on end.

"You probably forget the impor