118 SCHIAPARELLl's LATEST VIEWS REGARDING MARS. 



would progress luiicli further, and perhaps it would not be an exagger- 

 ation to say that the polar cap at the end of the warm season would 

 be entirely destroyed. But one can not doubt, in any case, that the 

 fixed i^ortiou of such a cap would be reduced to much smaller size, than 

 we see it to-day. Now, this is exactly what happens on Mars. The 

 long year, nearly double our own, permits the ice to accumulate during 

 the polar night of ten or twelve months, so as to descend in the form of 

 a continuous layer as far as parallel 70°, or even farther. But in the 

 day which follows, of twelve or ten months, the sun has time to melt 

 all, or nearly all, of the snow of recent formation, reducing it to such a 

 small area that it seems to us no more than a very white point. And 

 perhaps this snow is entirely destroyed; but of this there is at present 

 no satisfactory observation. 



Other white spots of a transitory character and of a less regular 

 arrangement are formed in the southern hemisphere upon the islands 

 near the pole, and also in the opposite hemisphere whitish regions 

 aj^pear at times surrounding the north pole and reaching to 50° and 

 55° of latitude. They are, perhaps, transitory snows, similar to those 

 which are observed in our latitudes. But also in the torrid zone of 

 Mars are seen some very small white spots more or less j)ersistent; 

 among others one was seen by me in three consecutive oppositions 

 (1877-1882) at the point indicated upon our chart by longitude 2G8° 

 and latitude ir>° north. Perhaps we may be permitted to imagine in 

 this place the existence of a mountain capalde of supporting extensive 

 ice fields. The existence of such a mountain has also been suggested 

 by some recent observers upon other grounds. 



As has been stated, the polar snows of Mars i^rove in an incontro- 

 vertible manner that this planet, like the earth, is surrounded by an 

 atmosphere capable of transporting vapor from one place to anotlier. 

 Tliese snows are in fact precipitations of vapor, condensed by the cold, 

 and carried with it successively. How carried with it if not by atmos- 

 pheric movement? The existence of an atmosphere charged with 

 vapor has been confirmed also by spectroscopic observations, princi- 

 pally those of Vogel, according to which this atmosphere must be of a 

 composition differing little from our own, and, above all, very rich in 

 aqueous vapor. This is a fact of the highest importance, because from 

 it we can rightly affirm with much probability that to water and to no 

 other liquid is due the seas of Mars and its polar snows. When this 

 conclusion is assured beyond all doubt, another one may be derived 

 from it of not less importance — that the temperature of the Arean cli- 

 mate, notwithstanding the greater distance of that planet from the 

 sun, is of the same order as the temperature of the terrestrial one. 

 Because, if it were true, as has been supposed by some investigators, 

 that the temj)erature of Mars was on the average very low (from 50° 

 to G0° below zero), it would not be possible for water vapor to be an 

 important element in the atmosphere of that planet, nor could water 



