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14 As the Martian spring progressed, the rifts spread, until at last they cut the ice-cap in two. The smaller portion then proceeded to disappear, while the larger shrank correspondingly in size. The relative times of disappearance of different parts of the cap give us some information about the relative elevations and depressions of the south circumpolar regions. In consequence, I have been able to construct a contour map of these polar portions of the planet. There are advantages in thus conducting polar expeditions astronomically. One not only lives like a civilized being through it all, but he brings back something of the knowledge he went out to acquire. There has even been vouchsafed the realization of that dream of explorers, an open polar sea; for as the first rift widened, Professor W. H. Pickering marked a large lake develop in the midst of it, in position almost over the pole. It seems cynical of fate thus to permit a Martian open polar sea to be seen before granting our earthly explorers a similar sight. As the snows dwindled in size, the blue band about them shrank to correspond. By August it was a barely discernible thread drawn round the tiny white patch which was all that remained of the enormous snow-fields of some months before. Finally, on October 13, the snow entirely disappeared, and the spot where it and its girdle, long since grown too small for detection, had been became one yellow stretch. That the blue was water at the edge of the melting snow seems unquestionable. That it was of the color of water, that it so persistently bordered the melting snow, and that it subsequently vanished are three facts mutually confirmatory of this deduction. Professor W. H. Pickering made the polariscope tell the same tale; for, on scrutinizing the great bay through it, he found the light coming from the bay to be polarized. Now, to polarize the light it reflects is a property, as we know, of a water surface. From all this we may conclude that we have here a polar sea, a real body of water. There is, therefore, water on the surface of Mars. We also mark that this body of water is ephemeral. It exists while the snow-cap is melting, and then it somehow vanishes. What becomes of i it, and whether there be other bodies of water on the planet, either permanent While it existed in any size, the polar sea was bordered on the north, all the way round and during all the time it was visible, by blue-green areas. These blue-green areas were strewn with several more or less bright regions, while below them came the great reddish-ochre stretches of the disc. Now, the blue-green areas have generally been considered to be seas, just as the reddish-ochre regions have been held to be land. That the latter are land there is very little doubt; not only land, but nothing but land,--land very pure and simple; that is, deserts. For they behave just as deserts should behave, chiefly by not behaving at all; remaining, except for certain phenomena to be specified later, unchangeable. With the so-called seas, however, the case is different. Several important facts conspire to throw grave doubt, and worse, upon their aquatic character. To begin with, they are of every grade of tint,--a very curious feature for seas to exhibit, unless they were or temporary, we shall now go on to inquire.