Cultivated fields as I am a living man!"
"What do you mean by your cultivated fields?" asked M'Nicholl sourly, wiping his glasses and shrugging his shoulders.
"Certainly cultivated fields!" replied Ardan. "Don't you see the furrows? They're certainly plain enough. They are white too from glistening in the sun, but they are quite different from the radiating streaks of Copernicus. Why, their sides are perfectly parallel!"
"Where are those furrows?" asked M'Nicholl, putting his glasses to his eye and adjusting the focus.
"You can see them in all directions," answered Ardan; "but two are particularly visible: one running north from Archimedes, the other south towards the Apennines."
M'Nicholl's face, as he gazed, gradually assumed a grin which soon developed into a snicker, if not a positive laugh, as he observed to Ardan:
"Your Selenites must be Brobdignagians, their oxen Leviathans, and their ploughs bigger than Marston's famous cannon, if these are furrows!"
"How's that, Barbican?" asked Ardan doubtfully, but unwilling to submit to M'Nicholl.
"They're not furrows, dear friend," said Barbican, "and can't be, either, simply on account of their immense size. They are what the German astronomers called Rillen; the French, rainures, and the English, grooves, canals, clefts, cracks, chasms, or fissures."
"You have a good stock of names for them anyhow," observed Ardan, "if that does any good."
"The number of names given them," answered Barbican, "shows how little is really known about them. They have been observed in all the level portion of the Moon's surface. Small as they appear to us, a little calculation must convince you that they are in some places hundreds of miles in length, a mile in width and probably in many points several miles in depth. Their width and depth, however, vary, though their sides, so far as observed, are always rigorously parallel. Let us take a good look at them."
Putting the glass to his eye, Barbican examined the clefts for some time with close attention. He saw that their banks were sharp edged and extremely steep. In many places they were of such geometrical regularity that he readily excused Gruithuysen's idea of deeming them to be gigantic earthworks thrown up by the Selenite engineers. Some of them were as straight as if laid out with a line, others were curved a little here and there, though still maintaining the strict parallelism of their sides. These crossed each other; those entered craters and came out at the other side. Here, they furrowed annular plateaus, such as Posidonius or Petavius. There, they wrinkled whole seas, for instance, Mare Serenitatis.
These curious peculiarities of the lunar surface had interested the astronomic mind to a very high degree at their first discovery, and have proved to be very perplexing problems ever since. The first observers do not seem to have noticed them. Neither Hevelius, nor Cassini, nor La Hire, nor Herschel, makes a single remark regarding their nature.
It was Schroeter, in 1789, who called the attention of scientists to them for the first time. He had only 11 to show, but Lohrmann soon recorded 75 more. Pastorff, Gruithuysen, and particularly Beer and Maedler were still more successful, but Julius Schmidt, the famous astronomer of Athens, has raised their number up to 425, and has even published their names in a catalogue. But counting them is one thing, determining their nature is another. They are not fortifications, certainly: and cannot be ancient beds of dried up rivers, for two very good and sufficient reasons: first, water, even under the most favorable circumstances on the Moon's surface, could have never ploughed up such vast channels; secondly, these chasms often traverse lofty craters through and through, like an immense railroad cutting.
At these details, Ardan's imagination became unusually excited and of course it was not without some result. It even happened that he hit on an idea that had already suggested itself to Schmidt of Athens.
"Why not consider them," he asked, "to be the simple phenomena of vegetation?"
"What do you mean?" asked Barbican.
"Rows of sugar cane?" suggested M'Nicholl with a snicker.
"Not exactly, my worthy Captain," answered Ardan quietly, "though you were perhaps nearer to the mark than you expected. I don't mean exactly rows of sugar cane, but I do mean vast avenues of trees—poplars, for instance—planted regularly on each side of a great high road."
"Still harping on vegetation!" said the Captain. "Ardan, what a splendid historian was spoiled in you! The less you know about your facts, the readier you are to account for them."
"Ma foi," said Ardan simply, "I do only what the greatest of your scientific men do—that is, guess. There is this difference however between us—I call my guesses, guesses, mere conjecture;—they dignify theirs as profound theories or as astounding discoveries!"
"Often the case, friend Ardan, too often the case," said Barbican.
"In the question under consideration, however," continued the Frenchman, "my conjecture has this advantage over some others: it explains why these rills appear and seem to disappear at regular intervals."
"Let us hear the explanation," said the Captain.
"They become invisible when the trees lose their leaves, and they reappear when they resume them."
"His explanation is not without ingenuity," observed Barbican to M'Nicholl, "but, my dear friend," turning to Ardan, "it is hardly admissible."
"Probably not," said Ardan, "but why not?"
"Because as the Sun is nearly always vertical to the lunar equator, the Moon can have no change of seasons worth mentioning; therefore her vegetation can present none of the phenomena that you speak of."
This was perfectly true. The slight obliquity of the Moon's axis, only 1-1/2°, keeps the Sun in the same altitude the whole year around. In the equatorial regions he is always vertical, and in the polar he is never higher than the horizon. Therefore, there can be no change of seasons; according to the latitude, it is a perpetual winter, spring, summer, or autumn the whole year round. This state of things is almost precisely similar to that which prevails in Jupiter, who also stands nearly upright in his orbit, the inclination of his axis being only about 3°.
But how to account for the grooves? A very hard nut to crack. They must certainly be a later formation than the craters and the rings, for they are often found breaking right through the circular ramparts. Probably the latest of all lunar features, the results of the last geological epochs, they are due altogether to expansion or shrinkage acting on a large scale and brought about by the great forces of nature, operating after a manner altogether unknown on our earth. Such at least was Barbican's idea.
"My friends," he quietly observed, "without meaning to put forward any pretentious claims to originality, but by simply turning to account some advantages that have never before befallen contemplative mortal eye, why not construct a little hypothesis of our own regarding the nature of these grooves and the causes that gave them birth? Look at that great chasm just below us, somewhat to the right. It is at least fifty or sixty miles long and runs along the base of the Apennines in a line almost perfectly straight. Does not its parallelism with the mountain chain suggest a causative relation? See that other mighty rill, at least a hundred and fifty miles long, starting directly north of it and pursuing so true a course that it cleaves Archimedes almost cleanly into two. The nearer it lies to the mountain, as you perceive, the greater its width; as it recedes in either direction it grows narrower.
