THE CANALS OF MARS.

Press, Volume LIV, Issue 9816, 27 August 1897, Page 7

THE CANALS OF MARS.

. ■» A Vast Irrigation SciimiE. ITiiey AiiE Thought to Bring Water to A TaiRSTV I\>ri7LATloN\ «'Weekly Press and Referee. " By the Rev. P. W. Fairclouoii. Many venrs ago Mr l'roctor published a map of Mars in green and red. The green was supposed to be water and the red land. The seas, continents and islands were well defined and carefully named, but many regarded that map with a shmg of incredulity, though Mr Proctor assured his readers that it was the result of a comparison of hundreds ef independent drawings. What then will the unbeliever say to the thousand-fold more wonderful chart which illustrates this article? It was once suggested that we should signal to Mars and Jupiter by means of huge geometrical figures produced by planting lines of trees on the great plains of Asia. Mars has anticipated the proposal ! A little patience might discover a whole book of Euclid in our illustration.

Once in every fifteen years Mars is in a very favourable position for observation. He is At the point of his eccentric orbit which is nearest to the sun while the earth ie at its most distant point, and between Mars and the sun. A fairly favourable opposition occurred about two years aejo, and in order to make the most of it an observatory was devoted to a rigid study of the planet. I believe the station was at an elevation of 8,000, in the pure air of Arizona. The observers were Professors Lowell and Pickering and others. Thoy were equipped with splendid instruments, and devoted •ome months to their work. Professor Xiowell lias recently published the result in a book entitled " Mars," and the chart which ig my subject is one of many which it contains. I have not yet been able to obtain the book, but Dr. Dallinger, well-known as a microscopist, has based some articles on it in the Weileyan Magazine. The chart is one of his copies. He gives other more local maps, but this chart of the greater part of the planet serves our purpose- best.

It must be remembered that as the girth of Mara is about 13,000 miles, that is the distance represented by the length of the chart. Near the equator the drawing is to scale, but, of course, Mercator's Projection, which gives equal length to the parallels of latitude near the pole and at the equator, greatly exaggerates the north and south, that is tho top end bottom of the chart. In the margin to the left tho position of the equator and of 40 degrees north and south are marked.

The dark portions are the green, or the "water," of R. A. Prootoi-'s chart. Tho lighter shade is the red, or the "land." Wore it not for the exaggeration of the "land" area the " water" would be seen to be about one third of tho whole. I had better Bay at once, however, that it appears as if the " land and water " idea must now be abandoned in favour of land only. It will be observed that the amazing " canals" pass through the dark shading as well as through tho lighter portions. But how could such lines be drawn upon the sea? Even Britannia has not •' ruled" the waves in that fashion, and, as Byron says, Time writes ne wrinkle on thine azure brow. Professor Pickering tested the green with the polariscope and is almost positive that it is not water. The markings on the green must surely remove any doubt that remained, for they are not a system to themselves, like lines of reef in the sea, but are part of the general system and of one design. In short, Professor Lowell regards the green as areas of vegetation, and the poUrisoope supports him. The " green," as we Jiave called it, is not constant in tint, but varies with tho seasons of the planet, just as our own fields do, though perhaps not to distinctly. The rod, however, is permanent as red desert earth or sand would be. This •' ochre " tint encroaches upon the green at the season when the green fades throughout its extent, which seems like an ox tension of the arid area in the drought of summer.

But to return to the " canals." They were first discovered twenty years ago by Sohiajuvrelli, and for nine years he had a monopoly of them. But in 1886 othera saw them, and they have now become recognised features, and their number has greatly increased. Of course first-class instruments and practiced observers aro required for their detection. The planet is rarely nearer than 40,000,000 of miles. Orer each a gulf his moons, one o! which may bo thirty miles in diameter, escaped notice until lees than twenty years ago. The " canals " cannot be less than thirty miles wide, but they are still extremely faint marks, aud must not be supposed to be as plain ns they aro in the chart. They have to Le scrutinized and traced with infinite pains and with endless repetition. They cannot as yet be photographed, because a long exposure would be required, and the planet rotates on its axis. It would bo like trying to take the portrait o! a skirt dancer by the old long exposure process.

These facts about the magnitude of objects that are faintly seen on Mars serve to show the absurdity of attempting to signal to him. An object on Ins surface 30 miles wide and 1000 miles long can be seen with our best *ppliances in the most favourable cirouraet*ncee. But an object, say 30 miles equore, *onld probably never be detected by man. Should the people of Mays be as curious and M ingenious as man, a signal from us that vaa only thirty miles square—that is, that Only covered 900 square miles of the earth's surface—would bo of no use. Besides, at the nearest points of the oi-bita, the earth turns her night side to Mars, and rises and •ets with the aun, ao that the signal would have to be a light. But not all the volcanoes and furnaces and flames on earth, if touetered and worked at full blast for a iwntury, would have any ohance of being Been by Mare, in daylight. I therefore confidently recommend my readers not to take any chare in this signalling proposal.

Professor Lowell 13 of opinion that the atmosphere of Mars is a very thin one, much *«>re rarefied than the atmosphere of the e&rth's highest mountain peak. The power ?t gravity on the planet's surface is only «*wt half what it is on the earth. It is ■nppoeed that the earth's gravity is not •efficient to retain hydrogen in a free state — J* B**8** wno free hydrogen in our atmosphere. The particles of this gas have such a terri6c *•*• of motion that they, or any other body moving at a like speed, would break clean **&y from the earth's attractive power. .*Jfo possible that gases whioh tho earth Chains down would break away from the «6o!er grasp of Mars. If so, we are prefor a scanty atmosphere on our neigh"°r, n and for one possibly very differently instituted from our own. In this atmoaphero it is believed that jHmy clouda havo been observed, though I ™nU Professor Lowell did not see any. -Chic suggests that Mare knows nothing of £»» as we know it. But then there are the unions snow caps ; what of them ? They •w admitted, but with a startling qualificattan. Eacli cap melt« entirely away in the ""nwier of its pole. The retreat of the vast *Wte skirt ia so rapid before the sun that it *& be noted from day to day. It is thero**j> not a mass of snow and ice auch as Wned Nansen: winch a century of polar JJMMhlnes would scarcely conquer, it ia Wtle more than a hoar froet, or, say, a light *•" of anow!

tChtt. we have lost the Martian mm, n .

duced his clouds to film, and his snow caps to sprinkles that are entirely melted every summer. This means a world of desert and drought. It is an unwelome idea, but it fits in with the theory of planetary life. The earth, were she cool enough, could easily soak up the film of water that we call the ocean, or her heated rocks in crystalising could utilise it. But she is hot and so keeps the water out for the present. The moon is very much smaller and hence colder, and has long been held to be as dry as a bone. It is true that there is a recent suspicion that faint vapours rise in the deep craters, and [ that iv those depths there are slight signs of refraction, indicating traces of an atmosphere. In the cratcre also it is suspected there arc monthly growths of some vegetation, say moss, which is believed to cause certain patches to change their colour slightly. But, in spite of these suspicions, the moon is practically destitute of moisture. Now Alar 3 i 3 larger than the moon and smaller than the earth, and so may be in a middle condition as to internal heat and surface moisture. Let us suppose, then, an ancient world whose waters in the process of ages have steadily sunk away. Its intelligent and industrious population through millenniums oi time devote themselves to making the best of such stores of moisture as their impoverished planet yet possesses. Irrigation becomes the predominant industry, the one all absorbing care of their race. For this, war must cease and nations must federate. The uniform and inter-dependent system of canals that girda the planet cannot be owned by hostile powers. That, at least, ia a pleasant thought. But to follow our race of irrigationists. They discover that " the climate is changing" and vast tracts turning to desert, while the moister districts produce by nature less and less as centuries pass. They learn that at the poles every summer there is a, to them, vast waste of water from melted snow. With infinite toil they construct many artificial Niles to bring this boon to their Egypt. They distribute it far and wide by canals. As ages pass these works extend to hundreds of thousands of miles, and aa the naturally moist area decreases the canal skeleton remains far out in what would otherwise be desert. Along the canals they irrigate for miles on either side, making a belt of vegetation thirty miles wide and more. Where the canala intersect and at some other favourable spots they greatly extend the width of cultivation, making large circular oases. Where there are regions of high land—as possibly I in the light area lying between the dark masses on the chart—only a few large streams are led across in favourable localities, and these are hundreds of miles apart, but where the surface is favourable the canals aro tenfold more abundant.

Now, ifc must not be supposed that the chart shows all the canals that exist. The recent observers have discovered four times aa many as were known to Schiaparelli, and there may be thousands too small ever to be seen. Professor Lowell baseg his theory of irrigation on the following facts :—(1) The lines are of uniform width and perfectly straight. Nature has no such lines; (2) The system of canals is highly scientific, and there is an evident common design; (3) A glistening, as of water, was observed at the edge of the melting snow and the polariscope declared ifc to be water ; (4) The canala are not always visible. They die away in the autumn—as vegetation withers. In 1881, when the planet was at his nearest, the canals could net be seen, but as he moved further away they began to appear faintly, and darkened as the season of growth advanced ; (5) On the canals leading from the polar regions the darkening begins at the polar end, that is at the part first reached by the fertile flood—it must be remembered that the water would have thousands of miles to travel. The canals are said to become visible in an order harmonising with this idea of the somewhat slow arrival of the irrigating medium.

Supposing the theory to be accepted till a better arrives, it would be interesting to take a census of the Martian population. There are, say, at a moderate estimate 200,000 miles of canals. With an average width o£ thirty miles of cultivation there would be six million square miles of irrigated country, say twice the area of the United States. Now irrigated country ie of necessity densely populated—say 500 to the square mile. That would give us three thousand millions, or twice the population of the earth, supported by the canals. What a nation of market gardeners, to be sure !

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