Part 5 (1/2)
_Suggested Origin of the Blue Patches._
These heavy gases, mainly perhaps, as has been often suggested, carbon-dioxide, would, when in large quant.i.ty and of considerable depth, reflect a good deal of light, and, being almost inevitably dust-laden, might produce that blue tinge adjacent to the melting snow-caps which Mr. Lowell has erroneously a.s.sumed to be itself a proof of the presence of liquid water. Just as the blue of our sky is undoubtedly due to reflection from the ultra-minute dust particles in our higher atmosphere, similar particles brought down by the 'snow' from the higher Martian atmosphere might produce the blue tinge in the great volumes of heavy gas produced by its evaporation or liquefaction.
It may be noted that Mr. Lowell objects to the carbon-dioxide theory of the formation of the snow-caps, that this gas at low pressures does not liquefy, but pa.s.ses at once from the solid to the gaseous state, and that only water remains liquid sufficiently long to produce the blue colour' which plays so large a part in his argument for the mild climate essential for an inhabited planet. But this argument, as I have already shown, is valueless. For only very deep water can possibly show a blue colour by reflected light, while a dust-laden atmosphere--especially with a layer of very dense gas at the bottom of it, as would be the case with the newly evaporated carbon-dioxide from the diminis.h.i.+ng snow-cap --would provide the very conditions likely to produce this blue tinge of colour.
It may be considered a support to this view that carbonic-acid gas becomes liquid at--140 F. and solid at--162 F., temperatures far higher than we should expect to prevail in the polar and north temperate regions of Mars during a considerable part of the year, but such as might be reached there during the summer solstice when the 'snows' so rapidly disappear, to be re-formed a few months later.
_The Double Ca.n.a.ls._
The curious phenomena of the 'double ca.n.a.ls' are undoubtedly the most difficult to explain satisfactorily on any theory that has yet been suggested. They vary in distance apart from about 100 to 400 miles. In many cases they appear perfectly parallel, and Mr. Lowell gives us the impression that they are almost always so. But his maps show, in some cases, decided differences of width at the two extremities, indicating considerable want of parallelism. A few of the curved ca.n.a.ls are also double.
There is one drawing in Mr. Lowell's book (p. 219) of the mouths, or starting points, of the Euphrates and Phison, two widely separated double ca.n.a.ls diverging at an angle of about 40 from the same two oases, so that the two inner ca.n.a.ls cross each other. Now this suggests two wide bands of weakness in the planet's crust radiating probably from within the dark tract called the 'Mare Icarium,' and that some widespread volcanic outburst initiated diverging cracks on either side of these bands. Something of this kind may have been the cause of most of the double ca.n.a.ls, or they may have been started from two or more craterlets not far apart, the direction being at first decided by some local peculiarity of structure; and where begun continuing in straight lines owing to h.o.m.ogeneity or uniform density of material. This is very vague, but the phenomena are so remarkable, and so very imperfectly known at present, that nothing but suggestion can be attempted.
_Concluding Remarks on the 'Ca.n.a.ls.'_
In this somewhat detailed exposition of a possible, and, I hope, a probable explanation of the surface-features of Mars, I have endeavoured to be guided by known facts or accepted theories both astronomical and geological. I think I may claim to have shown that there are some a.n.a.logous features of terrestrial rock-structure to serve as guides towards a natural and intelligible explanation of the strange geometric markings discovered during the last thirty years, and which have raised this planet from comparative obscurity into a position of the very first rank both in astronomical and popular interest.
This wide-spread interest is very largely due to Mr. Lowell's devotion to its study, both in seeking out so admirable a position as regards alt.i.tude and climate, and in establis.h.i.+ng there a first-cla.s.s observatory; and also in bringing his discoveries before the public in connection with a theory so startling as to compel attention. I venture to think that his merit as one of our first astronomical observers will in no way be diminished by the rejection of his theory, and the subst.i.tution of one more in accordance with the actually observed facts.
APPENDIX.
_A Suggested Experiment to Ill.u.s.trate the 'Ca.n.a.ls' of Mars._
If my explanation of the 'ca.n.a.ls' should be substantially correct--that is, if they were produced by the contraction of a heated outward crust upon a cold, and therefore non-contracting interior, the result of such a condition might be shown experimentally.
Several baked clay b.a.l.l.s might be formed to serve as cores, say of 8 to 10 inches in diameter. These being fixed within moulds of say half an inch to an inch greater diameter, the outer layer would be formed by pouring in some suitable heated liquid material, and releasing it from the mould as soon as consolidation occurs, so that it may cool rapidly from the _outside._ Some kinds of impure gla.s.s, or the brittle metals bis.m.u.th or antimony or alloys of these might be used, in order to see what form the resulting fractures would take. It would be well to have several duplicates of each ball, and, as soon as tension through contraction manifests itself, to try the effect of firing very small charges of small shot to ascertain whether such impacts would start radiating fractures. When taken from the moulds, the b.a.l.l.s should be suspended in a slight current of air, and kept rotating, to reproduce the planetary condition as nearly as possible.
The exact size and material of the cores, the thickness of the heated outer crust, the material best suited to show fracture by contraction, and the details of their treatment, might be modified in various ways as suggested by the results first obtained. Such a series of experiments would probably throw further light on the physical conditions which have produced the gigantic system of fissures or channels we see upon the surface of Mars, though it would not, of course, prove that such conditions actually existed there. In such a speculative matter we can only be guided by probabilities, based upon whatever evidence is available.
CHAPTER VIII.
SUMMARY AND CONCLUSION.
This little volume has necessarily touched upon a great variety of subjects, in order to deal in a tolerably complete manner with the very extraordinary theories by which Mr. Lowell attempts to explain the unique features of the surface of the planet, which, by long-continued study, he has almost made his own. It may therefore be well to sum up the main points of the arguments against his view, introducing a few other facts and considerations which greatly strengthen my argument.
The one great feature of Mars which led Mr. Lowell to adopt the view of its being inhabited by a race of highly intelligent beings, and, with ever-increasing discovery to uphold this theory to the present time, is undoubtedly that of the so-called 'ca.n.a.ls'--their straightness, their enormous length, their great abundance, and their extension over the planet's whole surface from one polar snow-cap to the other. The very immensity of this system, and its constant growth and extension during fifteen years of persistent observation, have so completely taken possession of his mind, that, after a very hasty glance at a.n.a.logous facts and possibilities, he has declared them to be 'non-natural'-- therefore to be works of art--therefore to necessitate the presence of highly intelligent beings who have designed and constructed them. This idea has coloured or governed all his writings on the subject. The innumerable difficulties which it raises have been either ignored, or brushed aside on the flimsiest evidence. As examples, he never even discusses the totally inadequate water-supply for such worldwide irrigation, or the extreme irrationality of constructing so vast a ca.n.a.l-system the waste from which, by evaporation, when exposed to such desert conditions as he himself describes, would use up ten times the probable supply.
Again, he urges the 'purpose' displayed in these 'ca.n.a.ls.' Their being _all_ so straight, _all_ describing great circles of the 'sphere,' all being so evidently arranged (as he thinks) either to carry water to some 'oasis' 2000 miles away, or to reach some arid region far over the equator in the opposite hemisphere! But he never considers the difficulties this implies. Everywhere these ca.n.a.ls run for thousands of miles across waterless deserts, forming a system and indicating a purpose, the wonderful perfection of which he is never tired of dwelling upon (but which I myself can nowhere perceive).
Yet he never even attempts to explain how the Martians could have lived _before_ this great system was planned and executed, or why they did not _first_ utilise and render fertile the belt of land adjacent to the limits of the polar snows--why the method of irrigation did not, as with all human arts, begin gradually, at home, with terraces and channels to irrigate the land close to the source of the water. How, with such a desert as he describes three-fourths of Mars to be, did the inhabitants ever get to _know_ anything of the equatorial regions and its needs, so as to start right away to supply those needs? All this, to my mind, is quite opposed to the idea of their being works of art, and altogether in favour of their being natural features of a globe as peculiar in origin and internal structure as it is in its surface-features. The explanation I have given, though of course hypothetical, is founded on known cosmical and terrestrial facts, and is, I suggest, far more scientific as well as more satisfactory than Mr. Lowell's wholly unsupported speculation. This view I have explained in some detail in the preceding chapter.
Mr. Lowell never even refers to the important question of loss by evaporation in these enormous open ca.n.a.ls, or considers the undoubted fact that the only intelligent and practical way to convey a limited quant.i.ty of water such great distances would be by a system of water-tight and air-tight tubes laid _under the ground._ The mere attempt to use open ca.n.a.ls for such a purpose shows complete ignorance and stupidity in these alleged very superior beings; while it is certain that, long before half of them were completed their failure to be of any use would have led any rational beings to cease constructing them.