"Do you want to find some vegetation?" said Barbicane.
"I want to explain what you scientific men do not explain! My hypothesis will at least explain why these furrows disappear, or seem to disappear, at regular epochs."
"Why should they?"
"Because trees might become invisible when they lose their leaves, and visible when they grow again."
"Your explanation is ingenious, old fellow," answered Barbicane, "but it cannot be admitted."
"Why?"
"Because it cannot be said to be any season on the surface of the moon, and, consequently, the phenomena of vegetation on the surface of the moon cannot be produced."
In fact, the slight obliquity of the lunar axis keeps the sun there at an almost equal altitude under every latitude. Above the equatorial regions the radiant orb almost invariably occupies the zenith, and hardly passes the limit of the horizon in the polar regions. Therefore, in each region, according to its position, there reigns perpetual spring, summer, autumn, or winter, as in the planet Jupiter, whose axis is also slightly inclined upon its orbit.
The origin of these furrows is a difficult question to solve. They are certainly posterior to the formation of the craters and amphitheatres, for several have crossed them, and broken their circular ramparts. It may be that they are contemporary with the latest geographical epochs, and are only owing to the expansion of natural forces.
In the meantime the projectile had reached the altitude of the 40th degree of lunar latitude at a distance that could not be greater than 800 kilometres. Objects appeared through the telescopes at two leagues only. At this point rose under their feet the Helicon, 505 metres high, and on the left were the mediocre heights, which inclose a small portion of the Sea of Rains under the name of the Gulf of Iris.