Popular Science Monihly • 



191 



itself felt; weeks 

 must elapse before 

 sufficiently luxuri- 

 ant vegetation has 

 sprung into being 

 so that the courses 

 of the canals can 

 be traced each 

 spring and s u m - 

 mer. And the pe- 

 culiar manner in 

 which the canals 

 seem to creep down 

 from the poles at 

 the rate of two and 

 a half miles an 

 hour lends color to 

 the explanation. 



The Groivth and 

 Death of 



Vegetation on 



Mars 

 This elaborate 

 network of sluices 

 divides the planets 

 into plains of more 

 or less geometrical 

 shape. Blue, green 

 and orange are the 

 colors of these 

 plains — colors that 

 proclaim the char- 

 acter of the areas 

 in question. The 

 blue-green areas 

 are fertile regions 

 fed by the canals ; the orange sections are 

 deserts, hopelessly arid. This distinction 

 Professor Lowell draws by reason of the 

 peculiar fluctuations in hue which the 

 blue-green patches undergo with the ad- 

 vent of spring and winter. As autumn 

 approaches they assume a russet tint, 

 which renders it almost impossible to dis- 

 tinguish them from the orange deserts. 

 When the polar snows begin to melt they 

 gradually deepen in shade until they as- 

 sume the characteristic color of vegeta- 

 tion. Inasmuch as these changes are 

 closely linked with the waxing and wan- 

 ing of the canals, it is evident that the 

 one phenomenon is dependent upon the 

 other. 



That the spots toward which the ca- 

 nals converge are the objective points of 



Dr. Percival Lowell, who erected at 

 Flagstaff, Arizona, the finest private ob- 

 servatory in the world for the special study 

 of the planets. Here for many years he 

 has made those observations of Mars 

 which have made him the foremost au- 

 thority on that planet in the world 



Martian irrigation, 

 is demonstrated by 

 the scientific pre- 

 cision with which 

 the canals have 

 been drawn to meet 

 them. Not a soli- 

 tary spot is any- 

 where to be found. 

 Three, four, six, 

 even seventeen ca- 

 n a 1 s concentrate 

 their floods on a 

 single spot. In di- 

 ameter the spots 

 range from seven- 

 ty-five to one hun- 

 d r e d and fifty 

 miles. Like the ca- 

 nals they have been 

 designed with ge- 

 ometrical economy. 

 If there are cities 

 on ]\Iars, it is not 

 unlikely that they 

 are situated in 

 these spots. 



Like the canals 

 the spots disappear 

 with the approach 

 of winter; but be- 

 fore they are ex- 

 tinguished the ca- 

 nals have faded 

 away. This is as 

 it should be. Be- 

 fore our time the 

 spots were thought to be lakes and were 

 named accordingly. Professor Lowell 

 regards them as oases studding the Mar- 

 tian deserts. Lakes would never deepen 

 in color; only vegetation can cause the 

 characteristic fluctuations to which the 

 spots are subject. 



Are the Canals Real or Merely Illusions f 



The amount of ink that has been spill- 

 ed over the canals and their meaning 

 would fill a hogshead. IMany astrono- 

 mers deny that the canals exist at all and 

 regard them as optical illusions produced 

 by eye-strain. But none of these skeptics 

 has had the opportunity of studying 

 Mars night after night in a clear atmos- 

 phere, far from the smoke of cities. 

 Doubting astronomers who have troubled 



