In order to consider the attitude of the Earth in relation to the Sun and the nearest fixed star, we will reduce the Sun's diameter of 866,000 miles to the dimensions of a ball one inch in diameter; the Earth reduced to the same scale would be a minute speck less than one one-hundredth of an inch in diameter; a perforation in paper made by the finest cambric needle would represent the size of this minute speck, the Earth. Following this scale we should place this speck nine feet from the inch ball, this distance representing 93,000,000 of miles, the Earth's distance from the Sun; Mars would be a still smaller speck a step farther off. Let us now proceed to Boston Common, for example, and on the smooth playground place our inch ball representing the Sun; taking three good steps we should place our minute speck, representing the Earth, upon the ground where it would be immediately lost in the fine gravel; another step and we would place a still smaller particle, representing Mars. How big a circle on the Earth's surface, using the inch ball as a centre, should we have to describe in order to include the nearest fixed star? Such a circle would reach to Detroit, Michigan, and Columbus, Ohio, or Wilmington, North Carolina! To find a circle which would include eight other fixed stars next in distance, and only eight of the thousands which render the heavens so beautiful on a clear winter's night—we should run such a circle through the centre of Hudson Bay, the waters of southern Greenland, Lake Winnipeg, and New Orleans!
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.
In a planet devoid of atmosphere, or a sphere glowing with its own heat, we may decide without question that life does not exist. Even in a globe in many respects like our own it would be hazardous to conjecture the kinds of organic forms in which it is manifested. Reasoning from analogy, if life exists in Mars, or other spheres in infinite space, it must have originated under much the same conditions as it originated here; at the outset the most primitive bits of protoplasm. But has life appeared in Mars? Tyndall, in graphic words, pictures the rounding of worlds from nebulous haze, and then says, "For eons, the immensity of which overwhelms man's conception, the Earth was unfit to maintain what we call life. It is now covered with visible living things. They are not formed of matter different from that around them. They are, on the contrary, bone of its bone and flesh of its flesh." Mars must come in the same category. It is a part of the original nidus from which our world was condensed, and however life originated in the past, the conditions for its origin, at least, must have been as favorable on the surface of Mars, as on the surface of the Earth, and, so far as we know to the contrary, even more favorable. In the beginning, Mars cooled and hardened with all those behaviors of contraction, condensation of vapor on its surface, erosion, etc., and it is impossible to avoid the conviction that life, as on our Earth, arose under the same physical conditions. Recalling the resemblance which Mars bears to the Earth, and the data which have already been established, we behold a world in many respects like ours, with its sunsets and sunrises, winds that sweep over its surface, the dust storms from the deserts, its snow-storms and snow-drifts, its dazzling fields of white in the north, with an occasional snow-storm that whitens the planet far down in latitude; the seasonal changes, and, most important of all, the melting ice caps, with rivulets and torrents, temporary arctic seas and frozen pools, its great expanses of vegetation and sterile plains. We have in Mars the variety of conditions under which life has assumed its infinite variety of aspects on the Earth, and which, by analogy, should have passed through similar stages in Mars. Life at the outset must have been protoplasmic; then came contractile tissue, muscular bundles, hardened structures within and without for their support, nerves to animate the muscles, and protection for nerve-trunk, either rigid or flexible. Hard parts might vary under a different force of gravity, though there might appear types of structure that could be classified with our own.
All such conditions, however, are mere surmises, for about such matters we can reason only from analogy. The first proposition to establish is that the conception of the plurality of worlds is not unreasonable, and second, that many of the most eminent astronomers have believed in the inhabitability of other worlds, and this justifies a reasonable man to follow the inquiry. The belief is based upon legitimate analogies which have thus far guided man in every generalization, in the establishment of principles, and are continually appealed to in the details of every day's experience.
From remote times it has been taken for granted by the best minds that other worlds besides ours sustain life. The early belief in the plurality of worlds was based on the idea that since spheres like ours had been fashioned by the Almighty they must have been made for the same purpose for which our globe seemed intended, to sustain life, and Scripture was freely quoted in support of the idea.