Herschel attributed their brilliant aspect to ancient streams of lava congealed by the cold, an opinion which has not been generally received. Other astronomers have seen in these inexplicable rays a kind of moraines, ranges of erratic blocks thrown out at the epoch of the formation of Tycho.
"And why should it not be so?" asked Nicholl of Barbicane, who rejected these different opinions at the same time that he related them.
"Because the regularity of these luminous lines, and the violence necessary to send them to such a distance, are inexplicable.
"Par bleu!" replied Michel Ardan. "I can easily explain to myself the origin of these rays."
"Indeed," said Barbicane.
"Yes," resumed Michel. "Why should they not be the cracks caused by the shock of a bullet or a stone upon a pane of glass?"
"Good," replied Barbicane, smiling; "and what hand would be powerful enough to hurl the stone that would produce such a shock?"
"A hand is not necessary," answered Michel, who would not give in; "and as to the stone, let us say it is a comet."
"Ah! comets?" exclaimed Barbicane; "those much-abused comets! My worthy Michel, your explanation is not bad, but your comet is not wanted. The shock might have come from the interior of the planet. A violent contraction of the lunar crust whilst cooling was enough to make that gigantic crack."
"Contraction let it be—something like a lunar colic," answered Michel
Ardan.