626 



NA TURE 



[Ol TOMER 29, 1896 



tlic spots, iccorded by Green and Mitchell, were also seen ; 

 these were found to consist of land at a higher level than 

 tliat in the surrounding neighbourhood, and formed of 

 ice-clad slopes which reflected brightly the solar rays. 



To place before the reader the different Martian 

 features, Mr. Lowell has adopted a very simple and 

 ingenious plan. He has plotted upon a globe all the 

 details that have been seen at his observatory, and 

 photographed the globe down from twelve different points 

 of view, the negatives being then made " to conform as 

 near as possible to the actual look of the planet." Under 

 " Areography ■' then the reader makes, so to say, a trip 

 round the planet, each of the most important markings 

 being described in the text. The wonderful network of 

 the canals is almost startling, so clearly do they stand 

 out, and the amount of detail observed surpasses anything 

 that has as yet been done. 



In the two illustrations (Figs. I and 2) which we repro- 

 duce, the reader can see for himself the network of canals 

 and the "oases" at the points of intersection of the 

 canals. The drawings show clearly the canals on the 

 darker portions of the surface inarkings, quite a modern 

 addition to Martian cartography. 



must be on a gigantic scale. If there be inhabitants, 

 then, as Mr. Lowell says, "irrigation must be the chief 

 material concern of their lives.'' 



Turning our attention now to those markings known 

 as canals, we seem to have before us what appears to be 

 a most perfect system of irrigation that could be con- 

 ceived. These canals form a regular network all over the 

 planet's surface, and apparently pass through the dark 

 as well as the lighter portions of the disc, as gathered 

 from observations of both Messrs. Douglass and Schae- 

 berle. Since they have been so often described before, 

 it is unnecessary to do so here : but one may remark that 

 their number has been considerably increased (more than 

 doubled). Further, at the points were the canals meet 

 one another, there have been observed, in every case, to 

 be spots present. These latter have never been seen 

 isolated : "There is apparently no spot that is not joined 

 to the rest of the system, not only by a canal, but by more 

 than one." The canals and spots further always appear 

 to grow together (see accompanying figures). 



Now these canals are not always visible on the surface 

 of the planet ; they appear to depend upon the seasons. 

 Observation shows that they undergo a distinct develop- 



:»n ;\hout Ma 

 Loniiitude i 



With regard to the so-called " .Seas," that is, the blue- 

 green areas, we are told that important facts conspire to- 

 gether to throw grave doubt upon their aquatic character. 

 The two chief of these are, first, that hundreds of thou- 

 sands of square miles of them disappear in an amaz- 

 ingly short space of time ; and, second, that polariscope 

 observations give no indications of polarisation. Two 

 questions then arise : first, where then does all the water, 

 formed from the melting of the polar cap, go ? and what 

 are, then, these blue-green areas ? The latter are, accord- 

 ing to Mr. Lowell, areas of vegetation, and they have been 

 observed to alter their tints as the seasons on the planet 

 progress : he suggests, howe\er, that they were prob- 

 ably once seas, but the supply of water has now so 

 diminished that it only flows in the deepest channels. He 

 defines them as being at present midway in evolution 

 lietween the seas of our earth and those of the moon. 



With such a state of affairs, a small water supply, the 

 inhabitants of Mars must, to exist, have a very elaborate 

 and scientific means of utilising every drop they can 

 procure ; or, in other words, their system of irrigation 



NO. 1409, VOL. 54] 



ment, and it is here that a clue may be found to their 

 origin. Let us regard this "development " as seen and 

 recorded by Mr. Lowell. A canal, according to him, 

 alters in visibility for some reason connected with itself ; 

 it grows into existence, but is always constant in position. 

 Their visible development apparently follows the melting 

 of the polar snows. They becoine distinct when the 

 melting has considerably progressed, and more so as the 

 season advances. Those which are \isible first lie to- 

 the southward, i.e. nearer to the south pole. It may 

 be mentioned here that the southern pole was tilted 

 during this opposition towards the earth. Latitude and 

 proximity to dark regions are the two main factors for 

 early visibility. Canals running north and south generally 

 become visible before those running east and west. 



With regard to the doubling of the canals, Mr. 

 Lowell's observations have led him to discover that this 

 does not occur all of a sudden, as has generally been 

 understood, but that there is an apparent mode of 

 development in the process. 



In the case of the Ganges, he says : " Hints of germina- 



