John remarked that if any of these bare or sparsely-covered places were large enough to be detected by our telescopes, in moments of extremely good seeing, we should no doubt be told that they afforded absolute proof that the canal lines are only disconnected markings, and the canals a myth.
"Very probably," I replied; "yet it should be obvious that vegetation would be sparse, or altogether absent, perhaps, for miles, in many places along the thousands of miles over which the canals extend, and also that it is quite likely, if we could use higher powers so as to get a better view of the lines, the edges would appear irregular. Nature is rarely symmetrical in her work, there is nearly always irregularity of growth; and in artificial cultivation it is neither possible nor desirable to fill up every acre of land simultaneously."
Merna then told us that, owing to extensions of their irrigation system, laterally, and the consequent growth of vegetation, the width of many of the canal lines would be seen to increase.
"Yes," said John, "and when that phenomenon is seen by our observers we shall be informed that such increase in width is still another proof that there are no canals upon Mars."
"Well, John," replied Merna, "it seems to me very strange that your people should so misinterpret the meaning of such indications. Do you really think such a contention would be put forward?"
"I'm quite sure of it," said John; "and we should be told that canals could not increase in width! Don't you agree with me, Professor?"
"Yes, John," I answered; "I have seen and heard so many contentions and arguments of a like nature that I cannot say your supposition is not justified.
"I may, however, point out that it is only when the most ideal conditions of seeing exist that we can ever hope to secure a view of the canal lines showing the apparent breaks in their continuity. I have on a previous occasion alluded to the drawbacks connected with the use of very large telescopes, and it may be well to sound a note of warning, for it would be very easy for an observer to be deceived by an illusory appearance of the breaking up of the canal lines into a series of scattered markings. This effect would undoubtedly occur in using a very large telescope in any but ideally favourable atmospheric conditions, for the high powers used with such large instruments would so exaggerate the most minute atmospheric tremors that any lines on the Martian surface would inevitably appear broken up, and an erroneous deduction might be drawn by the unwary observer. If well seen, the canal vegetation would appear as separate markings in alignment, but no telescope is ever likely to define well enough to show the actual canals, because they are so narrow."
We now returned to our air-ship, and went back to Sirapion; where, after making the necessary changes and preparations, we accompanied Merna to the City Hall, for the purpose of attending the banquet to which we had been invited by Soranho.