THE STRANGE MARKINGS ON MARS. 53 



and some of these may have an important bearing upon the ques- 

 tion of the nature of the canals. A glance at Schiaparelli's map 

 shows us the disk of the planet divided into areas of land and 

 water, which are about equal in their total extent. Then crossing 

 the land areas in every direction are the canals, which it will be 

 observed always begin and end either at the edge of a sea, or at a 

 point of junction with other canals. Without varying their direc- 

 tion they cross one another, and in some cases several canals radi- 

 ate from a single center, which then generally appears expanded 

 into a " lake." In addition there are certain regions which Schia- 

 parelli describes as variable in appearance, or intermediate be- 

 tween the seas and the lands, presenting sometimes the character 

 of maritime surfaces and at other times that of continental areas. 

 Among these are the places marked on the map Deucalionis Regio, 

 Hellas, and the island called Cimmeria. The region named Libya, 

 which ordinarily appears as a continental expanse, seems to belong 

 to this class of variable areas, and within the past year it has ob- 

 tained great celebrity because it was said to have been submerged 

 by an inundation from the adjoining sea. This region is more 

 than 200,000 square miles in area, and lies just under the equator. 

 In May last M. Perrotin, of the Nice Observatory, made the some- 

 what startling announcement that the continent of Libya had dis- 

 appeared. " Clearly visible two years ago," said M. Perrotin, in 

 his report to the Paris Academy of Sciences, " to-day it no longer 

 exists. The neighboring sea, if sea it is, has completely invaded 

 it. In place of the light reddish tint of the continents of Mars the 

 black, or rather dark-blue, color of the seas has appeared there. 

 ... In sweeping over the continent the sea has abandoned on the 

 south the region that it formerly occupied, and which now appears 

 with a tint intermediate between that of the continents and that 

 of the seas, a light-blue color, analogous to that of a slightly misty 

 sky in winter." 



A look at the accompanying cut will show the change which 

 Perrotin detected. This extraordinary aspect of Libya was first 

 seen in April and lasted into May. In June the "continent" 

 seems to have resumed, or nearly so, its ordinary appearance. 

 Perrotin's suggestion that the change observed was probably 

 periodic appears to be borne out by an examination of former ob- 

 servations of this region of the planet. There was a partial " in- 

 undation" of Libya in 1882, and a still more extensive one in 1884, 

 both of which were noted by Schiaparelli, who confirms Perrotin's 

 observation of 1888 in a general way, but does not describe the 

 continent as having at any time completely disappeared. Speak- 

 ing of its appearance in 1884, Schiaparelli says Libya had a flaky 

 look, as if it had been " covered with innumerable little spots all 

 jumbled together." The suggestion of clouds contained in this 



VOL. XXXV. — 4 



