Connected with the conduct of the canals is a phenomenon, examples of which were early noted in a general way by Schiaparelli and later, but of which the full import and exhibition only came to light during the opposition of 1903 by a very striking metamorphosis: what may be called the hibernation of a canal for a longer or shorter term of years. What observation discloses is certainly curious. For several successive oppositions a canal will be seen in a definite locality, as regular in seasonal recurrence as it is permanent in place, a well-recognized feature of the disk. Then to one’s surprise, with the next return of the planet, it will fail to appear, and will proceed to remain obliterate without assignable cause for many Martian years, until as unexpectedly it will be found what and where it was before. Neither to deposition of hoar-frost, such as frequently whitens whole regions of Mars, nor to other circumstances can be attributed its disappearance. Without apparent reason it simply ceases to be and then as simply comes back again.

Such bopeep behavior is quite beyond and apart from the seasonal change in visibility, to which all the canals are by their nature subject. For being creatures of the semi-annual unlocking of the water congealed about the polar caps, they quicken into growth and visibility, each in its season, and as regularly die out again. Different, however, is the phenomenon to which I now refer. In it not a seasonal but a secular change is concerned. The season proper to the canal’s increase will recur in due course, and the canals round about it will start to life, yet the canal remains unquickened. Nothing responds where in years the response was immediate and invariable. The canal lies dormant spite of seasonal solicitation to stir.

Such curious hibernation was early hinted to the keenness of Schiaparelli, and most incomprehensible as well as difficult of verification at that stage the phenomenon was. That the absence was a fact, however, he assured himself, although he was not able to prove an alibi. But at the last opposition an event of the sort occurred which, from the length of time the planet was kept under observation, combined with continued suitableness of the seeing, unmasked the process. In the light of what then happened, taken in connection with the side-lights thrown upon it by the canal’s past and by the knowledge we have meanwhile gained of the planet’s physical condition, the riddle of the phenomenon may in part at least be read, and most interesting and instructive the reading proves to be.

Among the initial canals detected by Schiaparelli, in 1877, was a tricrural set of lines recalling the heraldic design of three flexed legs joined equiangularly above the knees. It lay to the east of the Syrtis Major, and he called its three members the Thoth, the Triton, and the Nepenthes. Starting from the head of his gulf of Alcyonius, at a point now known to be occupied by the oasis called Aquae Calidae, the Thoth started south inclining westward as it went, till in longitude 267° and latitude 15° north, it met the Triton, which had come from the Syrtis Minor with similar westward inclination. To the same point in the same manner came the Nepenthes. Part way along the course of the latter was to be seen a small dark spot, the Lucus Moeris, which he estimated at four degrees in diameter. Some of the markings were easier than others, the easiest of all being the Lucus Tritonis, a largish dark spot at the common intersection of all three canals; but that none of the markings were remarkably difficult is sufficiently shown by their detection at this early stage of Schiaparelli’s observations. It is worth noting also that he discovered the southern ones first; the Thoth not being seen till March, 1878. As his then recognition of these canals witnesses, they must have been among the most evident on the disk. And the point is emphasized by the fact that he failed at this opposition to detect the Phison and the Euphrates as separate markings.

Much the same the three canals appeared to him at the next opposition of 1879, the Thoth being seen at its several presentations from October 5, 1879, to January 11, 1880.

At the next opposition a noteworthy alteration occurred, the full significance of which escaped recognition. Schiaparelli saw, at the place where the Thoth had been, two lines which he took for a gemination of that canal, one of which followed the course of the old Thoth, while the other went straight from the Sinus Alcyonius to the Little Syrtis, or, more precisely, to the junction of the Triton and the Lethes. It was not the Thoth, however, but something unsuspected, of more importance.

In 1884 the Thoth showed really double, the western line being much the stronger, “una delle piu grosse linee que si vedessero sul disco.” That neither branch went farther than the meeting-place with the Nepenthes argues that it was indeed the Thoth that was seen. Schiaparelli himself had no doubt on the subject, although he drew the double canal he saw due north and south from the tip of the Sinus Alcyonius to the junction, but nevertheless along the 263° meridian.

In 1886 and 1888 the system was in all essentials, what it had been in 1877 and 1879, except that the Thoth and Nepenthes were double and were more minutely seen.

Here, then, was a system of canals and spots which for six Martian years had been a persistent and substantially invariable feature of the Martian surface. Any changes in it had been of a secondary order of importance, while its general visibility was of the first. It is possible, then, to judge of my perplexity when in beginning my observations in 1894 no sign of the system could I detect. Of neither the Thoth, the Triton, the Nepenthes, nor the Lucus Moeris was there trace. And yet, from the other canals visible, it was evident that the disk was quite as well seen as it had been by Schiaparelli. Not only were practically all his canals there, but many much smaller ones were to be made out. And the same was true of the spots, a host of such not figured by him appearing here and there over the planet’s surface.

Nor was this all. Instead of the Thoth, another canal showed straight down the disk from the Syrtis Minor to the Aquae Calidae. This canal was as unmistakable as the Thoth had been before to Schiaparelli. It was among the first to be detected, and continued no less conspicuous to the end, the dates at which it was seen being July 10, August 14, and October 21. I called it the Amenthes, identifying it with the canal so named in Schiaparelli’s chart published in Himmel und Erde, of the ensemble of his observations from 1877 to 1888. But in his Memoirs he never called it so, seeing it, indeed, only in 1881-1882, and deeming it then the Thoth. Nevertheless, in 1894, it was the conspicuous canal of the region, and, what is more, had come, as it proved, to stay.

The invisibility of the Thoth continued for me the same during the succeeding oppositions of 1896-1897 and 1901. At the former opposition I drew it in 1896 on July 28, August 26, September 2, October 5-9, seeing it single; and in 1897 on January 12-19, February 21, and March 1. It was single but with suspicions of doubling in January, and was indubitably double in February. As for the Thoth, I had come to consider it and the Amenthes one, attributing their diversity of depiction to errors in drawing. For while the Thoth remained obstinately invisible, the Amenthes presented itself as substitute so insistently as to make one of the most obvious canals upon the disk.

One exception only was there to this state of things. On June 16, 1901, my notes contain this adumbration of a something else: “Amenthes sometimes appeared with a turn to it two-thirds way up; two canals concave to the Syrtis Major.”

So matters opened at the opposition of 1903. With the advent of the planet and the presentation in due course of Libya in February, the Amenthes duly appeared, much as it had showed at the opposition before, only less salient. It was a confused and seemingly narrower double. Suspected on the 16th of that month, it was definitely seen from the 18th to the 23d. Of the Thoth no mention is made either in the notes or in the drawings. When the region came round again, in March, the Amenthes was still there, showing more feebly, however, than it had in February, in spite of better seeing and the fact that the planet had considerably neared. Clearly the canal was fading out; a fact further witnessed to by the following note made on March 25: “Throughout this opposition thus far the dark triangle tipped by Aquae Calidae has been sharply divided in intensity from the Amenthes, which is very narrow and exceedingly faint.” Still was there no trace of the Thoth.

With the April presentation entered a new order of things. When the region first became visible, on the 16th, the Amenthes could still be seen and alone; but on the 19th, as the relative falling back of the Martian longitudes swung the region nearer the centre of the disk, the Thoth appeared alongside of it. On the 20th the Thoth showed alone. Unmistakable it was and just as Schiaparelli had drawn it, accompanied by the Triton and the curved Nepenthes. The thing was a revelation. What before I had seen only in the spirit of another’s drawings stood there patent to me in the body of my own; while the Amenthes, to which I had so long been accustomed, had vanished into thin air. Only a trace of it was now and then to be made out. So startlingly strange was the metamorphosis that I could not at first trust my eyes, and questioned the broken line, which had replaced the straight, for some ocular deception. But nothing I could do would rectify it. The Amenthes was gone and the Thoth stood in its stead.

At the next presentation, May 26 to June 8, the phenomena were repeated, and with increasing clarity. And then of a sudden, on May 29, I saw the long-given-up Lucus Moeris. There it was indubitably. And its definiteness was the most astonishing part of the affair. It was no question of difficult detection. Indeed, I had not been on the lookout for it, having searched the region too often fruitlessly before to have left incentive to search again. And so, when I was not searching, the thing of its own accord stepped forth to sight. It was a small round dot, like to any other oasis, and showed, as it were, a black pearl pendent by the Nepenthes from the Syrtis’s ear. For the Libyan bay made a dark projection of the sort high up on the Syrtis’s eastern side, from which the Nepenthes, precisely as Schiaparelli had drawn it, curved down to the point where the Thoth and Triton met. All three canals were geminated, the gemination being about three degrees wide.

And now occurred the last act in the drama. In July the Amenthes reappeared, showing alongside of the Thoth-Nepenthes, and thus removing any possible doubt as to their separate identity. It had, indeed, become the stronger of the two, having gained in strength in the interval between June and July and the Thoth-Nepenthes having lost. The lines were in process of relapsing into the status quo ante. Had these three presentations not been watched, the brief apparition of the Thoth-Nepenthes had been missed and with it the revealing of its curious character, and of certain deductions thereupon.

First among these is a truth of which I have long been convinced; to wit, that when a seeming discordance arises between the portrayals of a canal, it is commonly not a case of mistake nor of change, but one of separate identity. The canal has not shifted its place, nor has an error been committed; the fact is that one canal has been observed at one time, another at another.

So it was here, and thus were the old and the new observations reconciled. There had been no mistake in either. Two separate canals accounted for the discrepancy, and only an unfounded distrust of the accuracy possible in such observations was to blame for any failure to recognize the fact.

Now, scrutiny of the notes upon the appearance of the two canals, together with their labeling by the seasonal longitudes of the planet at the dates they were made, discloses a curious relation between the two. The seasonal longitudes are important, as they date the phenomena according to the Martian calendar. Ordered thus, the successive aspects reveal first a seasonal change in each canal and then over and above this a secular one. And this secular change was such as to cause the two canals to alternate in visibility. When the one was present the other was not, and vice versa.

We shall see this more clearly and at the same time bring out a curious relation between the two systems, the broken bow of the Thoth-Nepenthes-Triton and the straight arrow of the Amenthes, while looking at the cartouches of the Thoth, the Amenthes, and a combination of both given in the plate on previous page.

The antithetical character of the two canals is apparent. But what is further interesting, the combination cartouche of both bears a singular resemblance to that of the mean canal of the north tropic zone, the zone to which both canals belong. Here, then, is a combination which is perfectly regular while each of its constituents is anomalous.

And now we come to something as important: at the opposition of 1905 the curious alternation metamorphosis was enacted anew. The Amenthes appeared, disappeared to be replaced by the Thoth, and then reappeared again beside the other. This corroboration of behavior showed the previous observations to have been due to no mistake, and only served to deepen the interest in this last and more singular phase of canal conduct.