After consideration of all these facts; and despite the belief of some distinguished astronomers that changes are sometimes perceptible on the Moon's surface; and that hoar frost can be perceived there; and perhaps volcanic eruptions--the general conclusion arrived at by astronomical authority is that organic life does not exist either on the Moon or in it; and we may conclude this outline of the speculations concerning it by quoting the American astronomer, Professor N. S. Shaler: "It is naturally painful to conclude that the Moon is and always has been deprived of those features of existence which we deem the nobler; that it has never known the stir of air or water or the higher life of beings who inherit the profit of experience, and thereby climb the way that has led upward to man. That these large gifts have been denied to the nearest companion of the earth has its lesson for the naturalist. How vast are the effects arising from the interrelation of actions.... If the gases could have been retained in the Moon (by its attractive force) there is no reason why it should not have had the history of a miniature earth. As it is, from the beginning it appears to have been determined that the Sun should not warm it in the same way as the earth; that rain should not fall on it, nor the stirrings of life and energy be visible on it. There is no imaginable accident that can alter its state. Just as it is, our Moon is likely to see the Sun go out." This chapter may be ended by a brief application of some of these considerations to the case of the planet Mars. Next to the Moon Mars is our nearest neighbour, and the erection of great telescopes in America, one of them at Flagstaff Observatory, Arizona, where the air is extraordinarily clear and telescopic vision unusually penetrating, has stimulated the observation of the planet to a very great degree during recent years. Mars has an atmosphere not nearly so dense as that of the earth, but still dense enough in all probability to support some form of organic life. It may, for example, support vegetation. In some other respects Mars resembles the earth. It has arctic circles; it has clouds, though whether these are of vapour or of dust is not quite certain; and it has a less variable temperature by far than that of the Moon. There are, at any rate, some of the conditions to support and perhaps to encourage life; and if we could be certain that the atmosphere in Mars more nearly resembles that of the earth, and that its temperature was such as to be sometimes above that of our Arctic regions, then it would be difficult to deny that life, and probably intelligent beings, existed there. One very able and intelligent astronomer is convinced that life and intelligent beings do exist there. This is Professor Lowell, of Flagstaff Observatory, who has devoted a number of years and a great deal of money to the careful observation of the planet. He has brought