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 important difference between a _directrix_ and an _axis_," hotly observed Barbican. "I know what an _abscissa_ is, any how!" cried the Captain. "Can you say as much?" "Did you ever understand what is meant by a _double ordinate_?" asked Barbican, trying to keep cool. "More than you ever did about a _transverse_ and a _conjugate!_" replied the Captain, with much asperity. "Any one not convinced at a glance that this _eccentricity_ is equal to _unity_, must be blind as a bat!" exclaimed Barbican, fast losing his ordinary urbanity. "_Less_ than _unity_, you mean! If you want spectacles, here are mine!" shouted the Captain, angrily tearing them off and offering them to his adversary. "Dear boys!" interposed Ardan-- --"The _eccentricity_ is _equal_ to _unity_!" cried Barbican. --"The _eccentricity_ is _less_ than _unity_!" screamed M'Nicholl. "Talking of eccentricity--" put in Ardan. --"Therefore it's a _parabola_, and must be!" cried Barbican, triumphantly. --"Therefore it's _hyperbola_ and nothing shorter!" was the Captain's quite as confident reply. "For gracious sake!--" resumed Ardan. "Then produce your _asymptote_!" exclaimed Barbican, with an angry sneer. "Let us see the _symmetrical point_!" roared the Captain, quite savagely. "Dear boys! old fellows!--" cried Ardan, as loud as his lungs would let him. "It's useless to argue with a Mississippi steamboat Captain," ejaculated Barbican; "he never gives in till he blows up!" "Never try to convince a Yankee schoolmaster," replied M'Nicholl; "he has one book by heart and don't believe in any other!" "Here, friend Michael, get me a cord, won't you? It's the only way to convince him!" cried Barbican, hastily turning to the Frenchman.