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.
Amenthes with Thoth-Nepenthes. July.
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.
Cartouches
or
Curves of Visibility
of
Amenthes, Thoth and Their Combination.
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.