We will not here go to the length of examining in detail the conditions which obtain on the surface of all the bodies within range of our telescopes; but we may state that in none of them, with the exception of the planet Mars, is there any resemblance to our earth, and therefore life as we know it could not exist on them. With Mars, the case is different, and at first sight, there appears to be a state of things which approximates closely to that which obtains here. The planet Mars appears to the naked eye a deep red colour, and when examined with the telescope, we see that a large part of his surface is red; but between the red, and intersecting it in all directions, are patches and strips of a dull greenish hue. It was very soon conjectured that this green part was the Martial sea, and that the red was the land: this has been confirmed by later observations, and now no doubt exists on the point. The principal problem that we are here confronted with is this: assuming that what appears green on Mars is a liquid of some sort, can we assume that it is water, and not some other liquid with which perhaps we are unacquainted? This question appears at first sight impossible; for, unless we can bring some of the Martial sea down to the earth and analyse it, how can we determine its chemical constitution? The telescope evidently will not help us here, and we must call to our aid that powerful ally of the telescope—the spectroscope. The method of observation employed is a question which we cannot enter into here; it must suffice to state results, which all tend to prove that these seas are composed of water similar to ours. It must not be understood that we have been able to determine this directly; the only fact that we know for certain about it is, that in the Martial atmosphere there is a considerable quantity of water-vapour, which it is only fair to assume has been raised by evaporation from the seas, which are therefore also water.