They were not more fortunate with regard to another peculiarity of the disc, for they could not decide upon the cause of it. Michel Ardan was watching near the president, when he noticed long white lines, vividly lighted up by the direct rays of the sun. It was a succession of luminous furrows, very different from the radiation of Copernicus not long before; they ran parallel with each other. Michel, with his usual readiness, hastened to exclaim,— "Look there! cultivated fields!" Illustration: "WHAT GIANT OXEN." "Cultivated fields!" replied Nicholl, shrugging his shoulders. "Ploughed, at all events," retorted Michel Ardan; "but what labourers those Selenites must be, and what giant oxen they must harness to their plough to cut such furrows!" "They are not furrows," said Barbicane; "they are _rifts_." "Rifts? stuff!" replied Michel mildly; "but what do you mean by 'rifts' in the scientific world?" Barbicane immediately enlightened his companion as to what he knew about lunar rifts. He knew that they were a kind of furrow found on every part of the disc which was not mountainous; that these furrows, generally isolated, measured from 400 to 500 leagues in length; that their breadth varied from 1000 to 1500 yards, and that their borders were strictly parallel; but he knew nothing more either of their formation or their nature. Barbicane, through his glasses, observed these rifts with great attention. He noticed that their borders were formed of steep declivities; they were long parallel ramparts, and with some small amount of imagination he might have admitted the existence of long lines of fortifications, raised by Selenite engineers. Of these different rifts some were perfectly straight, as if cut by a line; others were slightly curved, though still keeping their borders parallel; some crossed each other, some cut through craters; here they wound through ordinary cavities, such as Posidonius or Petavius; there they wound through the seas, such as the Sea of Serenity. These natural accidents naturally excited the imaginations of these terrestrial astronomers. The first observations had not discovered these rifts. Neither Hevelius, Cassim, La Hire, nor Herschel seemed to have known them. It was Schroeter who in 1789 first drew attention to them. Others followed who studied them, as Pastorff, Gruithuysen, Bœer, and Moedler. At this time their number amounts to seventy; but, if they have been counted, their nature has not yet been determined; they are certainly not fortifications, any more than they are the ancient beds of dried-up rivers; for, on one side, the waters, so slight on the moon's surface, could never have worn such drains for themselves; and, on the other, they often cross craters of great elevation. We must, however, allow that Michel Ardan had "an idea," and that, without knowing it, he coincided in that respect with Julius Schmidt.