heyday of its youth, in June, 1894, when it was girdled by its broad blue belt. We have seen that we have reason to believe this to be in all probability 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 ice-cap is melting, and then it somehow vanishes. What becomes of it, and whether there be other bodies of water on the planet, either permanent or temporary, we will now go on to inquire.
As in the course of our inquiry we shall have occasion to refer familiarly to different Martian features, we had best begin it with some slight exposition of Martian geography, or of areography, as it may by analogy be called. To get this we will, by the help of Plates III. to XIV., suppose ourselves to be viewing the planet from some standpoint in space, and watching the surface features pass in procession under our gaze as the rotation of the planet brings them successively round into view. In the matter of names the map of the planet toward the end of the book, with its accompanying index, will give identification. We may thus make a far journey without leaving home, and from the depths of our arm-chairs travel in spirit to lands we have no hope of ever reaching in body.