CLOUDS AND RIVERS, ICE AND GLACIERS. 29 



here noticed. You frequently see a streamer of cloud 

 many hundred yards in length drawn out from an 

 Alpine peak. Its steadiness appears perfect, though a 

 strong wind may be blowing at the same time over the 

 mountain head. Why is the cloud not blown away? 

 Tt is blown away ; its permanence is only apparent. At 

 one end it is incessantly dissolved, at the other end it 

 is incessantly renewed : supply and consumption being 

 thus equalized, the cloud appears as changeless as the 

 mountain to which it seems to cling. When the red 

 sun of the evening shines upon these cloud-streamers 

 they resemble vast torches with their flames blown 

 through the air. 



§ 9. Architecture of Snow. 



85. We now resemble persons who have climbed a 

 difficult peak, and thereby earned the enjoyment of a 

 wide prospect. Having made ourselves masters of the 

 conditions necessary to the production of mountain 

 snow, we are able to take a comprehensive and intelli- 

 gent view of the phenomena of glaciers. 



86. A few words are still necessary as to the forma- 

 tion of sno^v. The molecules and atoms of all sub- 

 stances, when allowed free play, build themselves into 

 definite and, for the most part, beautiful forms called 

 crystals. Iron, copper, gold, silver, lead, sulphur, when 

 melted and permitted to cool gradually, all show this 

 crystallizing power. The metal bismuth shows it in a 



