106 FROM NEBULA TO NEBULA 



Veritable congealed tide-iraves are they, following by 

 the very law of their formation the great circles of the 

 planet, and supported from beneath by the permanent 

 ice-crust As the sun moves northward or southward, 

 the new waves that keep forming take slightly different 

 courses, and give rise to new "canals." 



Now, when waves touch or cross they "interfere," 

 and create at the points of intersection hills of double 

 height and width. This, I take it, is the origin of 

 the "oases," and of the curious "carets.'- On this theory 

 it ceases to be mysterious why both canals and oases 

 are so segregated, why so many of them affect the polar 

 regions, and why they connect the "salient points.-' 



The dams, being composed of ice, would melt- away 

 were they not seasonally recruited. But they are, as 

 the gemination process eloquently attests. The seasonal 

 or capricious lightening and darkening of the canals 

 may be aptly explained by fresh snowfalls, or the melt- 

 ings of snow; which are doubtless as common and nat- 

 ural climatic phenomena there as here, and not especial- 

 ly significant. 



The same explanation ought to suffice for similar 

 general variations of color. The brilliant white diamond 

 points which Mr. Lowell has described can assuredly 

 be nothing else than islands capped with snow his own 

 theory of an exclusively land surface precluding him 

 from advancing the same natural conclusion. 



In one place in his book, Mr. Lowell graphically 

 describes a great Martian storm, in which the cloud was 

 estimated by him to be flying at a height of 14 miles 

 above the planet's surface. He expresses the opinion 

 that this cloud was compovsed of sand, "because its 

 color was almost that of the planet's surface," which, 

 as we already know, he assumes to be desert. Now if 



