120 SCHIAPARELLI'S LATEST VIEWS REGARDING MARS. 



and Tempe. Their brilliaucy generally diminishes and disappears at 

 the meridian hour of the i)lace, and is reenforced in the morning and 

 evening with very marked variations. It is possible tliat they may be 

 layers of cloud, because the upper portions of terrestrial clouds where 

 they are illuminated by the sun appear white. But various observa- 

 tions lead us to think that we are dealing rather with a thin veil of fog 

 instead of a true nimbus cloud, carrying storms and rain. Indeed, it 

 may be merely a temporary condensation of vapor under the form of 

 dew or hoar frost. 



Accordingly, as ftir as we may be permitted to argue from the 

 observed facts, the climate of Mars must resemble that of a clear day 

 upon a high mountain. By day a very strong solar radiation, hardly 

 mitigated at all by mist or vapor; by night a copious radiation from the 

 soil toward celestial space, and because of that a very marked refriger- 

 ation. Hence a climate of extremes, and great changes of temperature 

 from day to night, and from one season to another. And as ou the 

 earth at altitudes of 5,000 and 0,000 meters (17,000 to L'0,000 feet) the 

 vapor of the atmosphere is condensed only into the solid form, produc- 

 ing those whitish masses of suspended crystals which we call cirrus 

 clouds, so in the atmosphere of Mars it would be rarely possible (or 

 would even be impossible) to find collections of cloud capable of pro- 

 ducing rain of any consequence. The variation of the temperature 

 from one season to another would be notably increased by their long 

 duration, and thus we can understand the great freezing and melting 

 of the snow, which is renewed in turn at the poles at each complete 

 revolution of the planet around the sun. 



As our chart demonstrates, in its general topograpliy Mars does not 

 present any analogy with the earth. A third of its surface is occupied 

 by the great Mare Australe, which is strewn with many islands, and 

 the continents are cut up by gulfs and ramifications of various forms. 

 To the general water system belongs an entire series of small internal 

 seas, of which the Iladriacum and the Tyrrhenum communicate with it 

 by wide mouths, whilst the Cimmerium, tlie Sirenum, and the Solis 

 Lacus are connected with it only by means of narrow canals. We shall 

 notice in the first four a parallel arrangement, which certainly is not 

 accidental, as also not without reason is the corresponding position of 

 the peninsulas of Ausonia, Ilesperia, and Atlantis. The color of the 

 seas of Mars is generally brown, mixed with gray, but not always of 

 equal intensity in all places, nor is it the same in the same place at all 

 times. From an absolute black it may descend to a light- gray or to an 

 ash color. Such a diversity of colors may have its origin in various 

 causes, and is not without analogy also upon the earth, where it is noted 

 that the seas of the warm zone are usually much darker than those 

 nearer the pole. The water of the Baltic, for example, has a light, 

 muddy color that is not observed in the Mediterranean. And thus in 



