ICE CRYSTALS AT GREAT ALTITUDES. 



sufficient to precipitate vapour of water ascending 

 there, under any conditions at present known to us: 

 but there may be other conditions unknown to us, which 

 may largely prevail to modify these results: such for 

 instance as the retention of vapour in a state of intense 

 refrigeration in the form of exceedingly minute crystals 

 of ice, possibly in the condition of the finest films, or dust. 



The presumption that this would gradually settle 

 down towards the earth, on account of its superior 

 specific gravity over air, is as may be ; that would 

 greatly depend upon the force and the condition and 

 chemical composition of the higher currents in the great 

 unknown realms of space beyond our ken. 



But the fact that fine ice crystals do exist in large 

 quantities in the higher atmosphere, we hold to be 

 certain, from the fact that showers of such atoms have 

 been seen to fall in our own country, and are reported 

 on the authority of intelligent arctic explorers to be 

 always falling, during still weather, in the great cold 

 of the polar winters. The result of experiments in one 

 case showed that the quantity thus falling in only 

 twelve hours, represented nine tons per square mile.* 

 There is the further fact of heavy snowstorms occurring 

 at intervals throughout the polar winter, which shows 

 that notwithstanding the intense cold always existing 

 the air has still remained surcharged with vapour. 



Before we pass on to other matters, we desire in 

 connection with this question to draw attention to the 

 enormous quantities of water which are known occasionally 

 to be held in suspension in the atmosphere, as evidenced 

 by the instances of the tremendous annual rainfalls which 

 have been recorded in Burma, in Brazil, and in many 



* See The Shores of the Polar Sea, by Dr. E. L. Moss, M.D., 1878, p. 44- 



