So far as the observer is concerned, what occurs is this: Upon a part of the disk where up to that time a single canal has been visible, of a sudden, some night, in place of the single canals he perceives twin canals,—as like, indeed, as twins, if not more so, similar both in character and in inclination, running side by side the whole length of the original canal, usually for upwards of a thousand miles, of the same size throughout, and absolutely parallel to each other. The pair may best be likened to the twin rails of a railroad track. The regularity of the thing is startling.
In good air the phenomenon is quite unmistakable. The two lines are as distinct and as distinctly parallel as possible. No draughtsman could draw them better. They are thoroughly Martian in their mathematical precision. At the very first glance, they convey, like all the other details of the canal system, the appearance of artificiality. It may be well to state this here definitely, for the benefit of such as, without having seen the canals, indulge in criticism about them. No one who has seen the canals well—and the well is all-important for bringing out the characteristics that give the stamp of artificiality, the straightness and fineness of the lines—would ever have any doubt as to their seeming artificial, however he might choose to blind himself to