In this broad way only can we form a dim conception of the overwhelming distances of space, and, in this absolutely unthinkable space, our little Sun, with its constant rain of meteoric dust, an occasional comet, and its microscopic planets are literally bunched together. To admit, as we must then, that one of these motes has had irrigating canals on various parts of its surface since prehistoric times, and the other mote has nothing of the sort despite the geodetic lines that are seen marking its surface, is simply preposterous. Their disposition, their visibility coincident with the Martian summer, becoming apparent only when the snow caps melt, their convergence towards centres of distribution, all go to prove by the simplest analogy an identity of structure. Certainly the overwhelming force of Lowell's observations and arguments baffles any other reasonable explanation of the character and purpose of these markings. Here are the lines, some following the arcs of great circles, all appearing precisely when they should appear, and in progressive strength from the north when the vivifying water from the melting snow cap first starts the vegetation. Why certain parallels or doublings are observed in some of the canals is about as puzzling to us as the checkerboard townships of the West would appear to a Martian, where some would be yellow with the ripening grain while others, uncultivated, would appear of a different color. III OTHER WORLDS INHABITED _Whether the other fixed stars have similar planetary companions or not is to us a matter of pure conjecture, which may or may not enter into our conception of the universe. But probably every thoughtful person believes with regard to those distant suns that there is in space something besides our system on which they shine._ TYNDALL. It would be a waste of time to attempt an interpretation of the markings of Mars as a result of intelligent effort, if it could be proved beyond a reasonable doubt that our globe was not only unique among the bodies which probably accompany the innumerable suns, but was the only body, among them all, sustaining creatures of intelligence. If life exists in other planets of a nature with which we are familiar, then the physical conditions must be similar to those of our own planet. Later we shall point out the infinite variety of conditions under which life--even man--exists on this globe, and it will be shown that the question of higher or lower temperature, more or less humidity, higher or lower atmospheric pressure, greater or less force of gravity, can have but little weight in discussing the probability of life in other worlds.