92 A CENTURY'S PROGRESS IN ASTRONOMY. 



black spots, to which he gave the name of 

 " lakes," in keeping with the view that the dark 

 regions of the planet were seas. 



In 1894 Percival Lowell erected at Flagstaff, 

 Arizona, an observatory for the specific purpose 

 of observing Mars and its canals in good and 

 steady air. He was assisted by W. H. Pickering 

 and by Andrew Ellicott Douglass (born 1867). 

 During a year's study Douglass measured the 

 Martian atmosphere and discovered canals cross- 

 ing the dark regions of the planet, finally dis- 

 proving the idea of their aqueous character. 

 Lowell recognised all Schiaparelli's canals, and 

 discovered many more. He also attentively 

 studied the south polar cap of Mars, which dis- 

 appeared entirely on October 12, 1894. Lowell 

 noticed, also, that as the cap melted the canals 

 became darker, as if water was being conveyed 

 down; and accordingly he adopted the view 

 put forward by Schiaparelli, that the canals are 

 waterways lined on either side by banks of 

 vegetation. His observations were published in 

 the end of 1895 in his work 'Mars/ He is of 

 opinion that the reddish-ochre regions or "con- 

 tinents" are deserts, and the greenish areas 

 marshy tracts of vegetation. The lakes are 

 named by him "oases," and, as Miss Clerke 

 observes, he " does not shrink from the full 



