192 THE POPULAR SCIENCE MONTHLY. 



acters to those of the solar spectrum, and this proves that the atmos- 

 phere of Mars is analogous to that of earth. But what is that atmos- 

 pheric matter which produces these significant lines ? From an exami- 

 nation of their positions, we find that they are not owing to the presence 

 of oxygen, nitrogen, or carbonic acid, but to watery vapor. There- 

 fore, there is water-vapor in the atmosphere of 3£ars, as in that of the 

 earth. The green spots on its globe are seas — expanses of water re- 

 sembling our seas. The clouds are made up of minute vesicles of 

 water, like our own mists ; and the snows consist of water solidified 

 by cold. Furthermore, this water, as revealed by the spectroscope, 

 being of the same chemical composition as terrestrial waters, we know 

 that Mars possesses oxygen and hydrogen. 



These important data enable us to form an idea of Martial me- 

 teorology, and to recognize therein a reproduction of the meteorologi- 

 cal phenomena of our own planet. On Mars, as on earth, the sun is 

 the supreme agent of motion and of life. Heat vaporizes the water 

 of the seas, causing it to ascend into the atmosphere. This vapor as- 

 sumes visible shape by the same processes which produce clouds here, 

 i. e., by differences of temperature and of saturation. Winds arise in 

 virtue of these same differences of temperature. We can observe the 

 clouds on Mars as they are swept along by air-currents over the seas 

 and continents, and several observers have, so to speak, photographed 

 these meteoric variations. 



If we are as yet unable precisely to see the rain falling on the 

 plains of Mars, we can at least tell when it is falling, for we can see 

 the clouds dispersing and gathering again. Thus there is on Mars, 

 just as on earth, an atmospheric circulation, and the drop of water 

 which the sun takes from the sea returns thither after it has fallen 

 from the cloud which concealed it. And, although we must sternly 

 resist any tendency to fashion imaginary worlds after the pattern of 

 our own, still Mars presents to us, as in a mirror, such an organic like- 

 ness to earth, that it is hard for us not to carry our description a little 

 further. 



Thus, then, we behold, in space, millions of miles away, a planet 

 very much like our own, and where all the elements of life exist, as 

 they do here — water, air, heat, light, winds, clouds, rain, streams, val- 

 leys, mountains. To complete the resemblance, the seasons there are 

 very much the same as here, the axis of rotation of Mars having an 

 inclination of 27°, while that of the earth is 23°. The Martial day is 

 forty minutes longer than the terrestrial. 



In the face of all these facts, can we be content with the conclu- 

 sions we have so far reached without going further, and considering 

 ulterior consequences ? If the same physico-chemical conditions are 

 present on Mars as on earth, why should they not produce the same 

 effects there as here ? On earth the smallest drop of water is peopled 

 with myriads of animalcules, and earth and sea are filled with count- 



