"Yet greater was my astonishment when, on the 19th of January, I saw the canal Jamuna, which was then in the center of the disk, formed very rigidly of two parallel straight lines, crossing the space which separates the Niliac Lake from the Gulf of Aurora. At first sight I believed it was an illusion, caused by fatigue of the eye and some new kind of strabismus, but I had to yield to the evidence. After the 19th of January I simply passed from wonder to wonder; successively the Orontes, the Euphrates, the Phison, the Ganges, and the larger part of the other canals, displayed themselves very clearly and indisputably duplicated. There were not less than twenty examples of duplication, of which seventeen were observed in the space of a month, from the 19th of January to the 19th of February. "In certain cases it was possible to observe precursory symptoms which are not lacking in interest. Thus, on the 13th of January, a light, ill-defined shade extended alongside the Ganges; on the 18th and the 19th one could only distinguish a series of white spots; on the 20th the shadow was still indecisive, but on the 21st the duplication was perfectly clear, such as I observed it until the 23d of February. The duplication of the Euphrates, of the canal of the Titans, and of the Pyriphlegethon also began in an uncertain and nebulous form. "These duplications are not an optical effect depending on increase of visual power, as happens in the observation of double stars, and it is not the canal itself splitting in two longitudinally. Here is what is seen: To the right or left of a pre-existing line, without any change in the course and position of that line, one sees another line produce itself, equal and parallel to the first, at a distance generally varying from six to twelve degrees--i.e., from 350 to 700 kilometres (217 to 434 miles); even closer ones seem to be produced, but the telescope is not powerful enough to distinguish them with certainty. Their tint appears to be a quite deep reddish brown. The parallelism is sometimes rigorously exact. There is nothing analogous in terrestrial geography. Everything indicates that here there is an organization special to the planet Mars, probably connected with the course of its seasons."[1] [Footnote 1: L'Astronomie, vol. i, 1882, pp. 217 _et seq._] Schiaparelli adds that he took every precaution to avoid the least suspicion of illusion. "I am absolutely sure," he says, "of what I have observed." I have quoted his statement, especially about the duplication of the canals, at so much length, both on account of its intrinsic interest and because it has many times been argued that this particular phenomenon must be illusory even though the canals are real.