Page:Popular Science Monthly Volume 71.djvu/287

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However, these remarks are probably quite useless. No one of good eyesight, who has seen Mars at Flagstaff, on a night when the seeing is really good, needs any arguments to convince him that what he sees is real. And no one who has made up his mind beforehand, without seeing them, that the double canals are due to diffraction, is likely to be influenced by these words.

It would seem almost unnecessary to state that no one for a moment supposes that the lines that one sees are actual streams of water. They are thought to be broad stretches of vegetation, dependent on channels of water running through them. So would the valley of the Nile appear to a distant observer, who would distinguish the dark fertile valley against the sands of the desert, long before he could see the river itself.

During the writers visit to Flagstaff, he saw 77 canals, 20 oases, and 11 double canals,[1] all of which, with one exception, could be readily identified on some one of Lowell's maps, though it was sometimes necessary to consult a map of an earlier date than the opposition cf 1905, to find them. Each of the drawings is the accumulated result of some 15 or 20 minutes at the telescope, so that no one of them represents ever}i;hing seen in a single night.

It must not be imagined that any drawing represents what the observer sees the moment he looks through the telescope. Instants of exceptional seeing flash out, here and there, at different spots on the planet. It is not till the same phenomena repeat themselves in the same way, in the same place, a great number of times, that the observer learns to trust these impressions. One has to keep one's mind constantly at the highest pitch to catch and retain what the eye sees.

It is like looking at a Swiss landscape from a high Alp, with the summer clouds sweeping about one. Now the mist rolls away, revealing a bit of the valley, and shuts in again in a moment: while in some other spot the clouds break away, and disclose a jagged summit, or a portion of a shining glacier.

Any one who has been fortunate enough to have had a really good view of the lineal markings on Mars is bound to be much impressed by their artificial appearance. So that, unless he has an inborn prejudice against the idea, any theory that accounts for the canals as the effort of intelligent beings to accomplish some definite object will not appear fanciful.

Lowell's theory that we have hero evidence that the inhabitants of

  1. There are known at present 436 canals, of which 51 are double, and 186 oases. These are never all seen at one opposition, not only because of the different tilts of the planet, but also because neighboring canals alternate in appearing and disappearing at different oppositions. Accepting Lowell's theory that the canals are areas of vegetation bordering artificial channels for irrigation, this could be accounted for by the fact that when the canals do not appear, the land is lying fallow.