5 o THE POPULAR SCIENCE MONTHLY. 



sory symptoms of the change. A light, hardly visible shade 

 would make its appearance, extended alongside one of the canals. 

 In a few days only a series of whitish spots would appear there. 

 A day or two later the perfect double of the canal would be seen 

 with absolute distinctness lying beside the original, exactly paral- 

 lel with it, and of equal length, breadth, and depth of color. 



" One can," says Schiaparelli, " compare this process of forma- 

 tion to the appearance that would be presented by a multitude of 

 soldiers dispersed without order who, little by little, should ar- 

 range themselves in ranks or in columns; so that we are here 

 dealing with formations unknown on the earth, determined by 

 the geographical configuration of the ground, and capable of re- 

 producing themselves periodically in the same places and under 

 the same aspects." 



These canals (we must continue to call them by that name for 

 lack of a better) vary in length from a few hundred miles to two 

 or three thousand, while their width is seventy-five or eighty 

 miles. When they become double, the distance between the twin 

 canals is from two hundred and fifty to five hundred miles. 



The Italian astronomer's later observations have again and 

 again confirmed the results of his earlier ones. During the oppo- 

 sitions of 1883 -'84, 1886, and 1888, under somewhat varying 

 conditions, and with different degrees of visibility, yet always 

 unmistakably, he has seen not only the canals, but the strange 

 phenomenon of their doubling or gemination. The character of 

 the appearances has been always the same, but in details they 

 have differed. 



Let the reader compare Schiaparelli's map with the chart of 

 Mr. Proctor, and he can not fail to be impressed by the enormous 

 advance in the matter of minute detail exhibited by the former. 

 Apparently more has been learned about the surface of Mars 

 during the past twelve years than was learned in the previous 

 two hundred years, and the greater part of this gain is the work 

 of a single observer. 



While it is more or less idle to speculate on the nature of these 

 singular objects appearing on a globe that never approaches the 

 earth nearer than about forty millions of miles, and that ordi- 

 narily is very much farther away, yet it is impossible to avoid 

 indulging a natural curiosity to know what they are. It is known 

 that all the features of Mars's globe are more or less change- 

 able, though upon the whole they preserve the same general 

 aspect, and Schiaparelli declares that in the case of the canals 

 the changes are not only extensive but periodical. It has gen- 

 erally been believed that the variations of appearance in the 

 larger features of the disk were owing principally to atmospheric 

 causes. Large regions of the planet have, at times, been seen 



