Page:Mars - Lowell.djvu/111

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87
THE POLAR CAP

one hundred millions of miles, found to note them but one watcher, alone on a hill-top with the dawn.

Calculation showed the position of the star-points to be in longitude 280° and 290° and in latitude 76° south. At this place on the planet, then, there was a range of slopes sufficiently tilted to reflect the Sun from their ice-clad sides. On comparing its position with Green's map of his observations upon the cap at Madeira in 1877, it appeared that this was the identical position of the spot where he had seen star-points then, and where Mitchell had seen them in 1846, to whom they had suggested the same conclusion. Green christened them the "Mitchell Mountains." At the times both these observers saw them, they were detached from the rest of the cap. At the time of this observation in June, they were still in the midst of the cap. We shall see that they eventually became islands, just as Green saw them, and that the observation in June marked an earlier stage in their history.

On June 10 Mr. Douglass detected a second rift in the cap backing the range of slopes. And on June 13 I noticed that behind the bright points the snow fell off shaded to this rift. Meanwhile a third rift had been made out by him, running from longitude 170 degrees to longitude 90 degrees,—very nearly, therefore, at right