quent oppositions. In 1879 Scliiaparelli noticed that the canal which he calls Nilus (see his map) was double, or consisted of two streaks running side by side, and perfectly parallel. This observation was made shortly after the time of the vernal equinox on Mars.
"These two regular, equal, and parallel lines," he says, "I confess profoundly surprised me, all the more because a few days before, the 23d and 24th of December, I had carefully examined that same region without discovering anything of the kind. I awaited with curiosity the return of the planet in 1881 in order to see if an analogous phenomenon would present itself in the same place, and I saw the same thing reappear on the 11th of January, 1883, one month after the vernal equinox of the planet, which had occurred on the 8th of December, 1881. The duplication was still plainer at the end of February. At this same date, the 11th of January, another duplication had already been produced, that of the middle section of the canal of the Cyclops at the edge of Elysium (see map). Greater still was my astonishment when, on the 19th of January, I saw the canal Jamuna, which was then in the center of the disk, composed very plainly of two parallel straight lines traversing the space which separates the Niliacus Lacus from the Auroræ Sinus, At first I thought it was an illusion caused by fatigue of the eye and by some new kind of strabismus; but there was no resisting the evidence. From the 19th of January I simply went from surprise to surprise; the Orontes, the Euphrates, the Phison, the Ganges, and most of the other canals showed themselves very clearly, and indubitably divided in two."
It is not a matter for surprise that this announcement of Schiaparelli's, coming upon the heels of his original discovery of the canals as single lines, which in itself was sufficiently remarkable, caused still greater doubt to be entertained of the correctness of his observations. It seemed to many easier to believe that a distinguished astronomer and practiced telescopist had been misled by some deception of the eyes, some optical trick of his instrument or of the atmosphere, than that the globe of Mars was covered, over the larger part of its surface, with a network of lines, apparently connected with the water-system of the planet, and that, at certain times, these lines, canals, or water-courses, or whatever they might be, were doubled up throughout their whole extent. Even the positive assurance of the celebrated astronomer, "I am absolutely certain of what I have observed," could not banish all doubt. The manner in which the doubling of the canals was brought about seemed most mysterious, and added to the apparently dubious character of the whole occurrence. Schiaparelli declared that sometimes he was able to perceive precur-
