be certain that the planets are inhabited. We know little more than this; Mars, the planet best situated for observation, has little or no atmosphere, and therefore, if inhabited, must be so by creatures not formed like human beings. There may, however, be some slight or thin atmosphere, as sometimes light shadows that appear like vapours have been seen on the planetary surface; but even on this point the best observers are doubtful. The polar ice-caps, known since the days of Herschel, do undoubtedly diminish during the Martian summer. Mr. Douglas, of Lowell Observatory, has remarked a dark edge to the melting ice, probably the water into which the ice is converted. This is not certain, because the polar caps may not be of ice at all; they may be of solid carbonic acid. The most eminent physicists doubt whether the sun's rays would have power to melt more than a few inches of snow or ice at the Martian, poles. The greatly disputed canals of Schiaparelli are still considered unproven. The word “canal” is a mistranslation of Schiaparelli's word “canale”; this, in Italian, does not mean “canal,” but “channel,” or watercourse. Some astronomers show these channels on their maps of Mars as sharp dark lines passing from point to point on the planet's surface; but Barnard, of the Lick Observatory (one of the most reliable observers, and aided by one of the largest telescopes in existence), says that the so-called channels are indistinct markings too hazy and undefined to be reproduced; this, too, when he is able to give other details not mentioned by Schiaparelli. A curious thing concerning the controversy is that some of the observers of the so-called canals' in Mars are able to distinguish similar lines not only on Mercury and Venus, but even on the satellites of Jupiter. The more cautious and conservative astronomers hesitate even yet to accept the Martian canal system, and one of them has caustically remarked that if you wish to see the canals well at night you must fix your eyes all the preceding day on Schiaparelli's map. The spectroscope in the hands of Keeler has made us acquainted with the fact that the outer portion of the rings of Saturn revolve more slowly than the inner. This implies that the rings are not composed of coherent matter, either solid or liquid, but of a cloud of minute particles, perhaps of a vaporous character, each moving in its own orbit. It is, however, in the domain of the fixed stars that the most interesting facts have been brought to light, and as spectrum analysis aids the telescope it is to be hoped that even greater wonders will be presented to our grasp. The most marvellous lesson revealed yet is as to the presence of dark, and therefore invisible, bodies in. the stellar spaces, and