FROST AND SNOW 291 



then the line, the thin course of the movement, becomes 

 a rigid mark. A few minutes later you may pick up from 

 the water a delicate stick of crystal, that fades at once in 

 your hand. The tip falling, perhaps, on to a fellow-crystal 

 in the water beneath, tinkles out a thin and bell-like note, 

 which is one of the most distinct and memorable sounds of 

 any season. It is scientifically, perhaps, an unexpected fact, 

 and a very happy one, that water as it approaches the 

 freezing point swells. We are accustomed to cold associated 

 with condensation, but if it did not happen that water 

 swelled as it froze the world would be uninhabitable in many 

 countries. The ice would sink to the bottom, build itself up 

 from the bottom to the top, and remain permanently where 

 now it is quickly thawed. Those who lament their cracked 

 pipes have at least this consolation, that if frozen pipes were 

 not forced outwards by frost the whole world would suffer. 



All that frost manufactures is ice. Hail and snow and 

 hoar frost and ' cat ice ' and icicles are as truly ice as the 

 smoothest and hardest and blackest that covers a pond. The 

 difference is that in snow and hoar frost or wherever the water 

 colour becomes opaque and bleaches, air is interposed. It 

 acts as oxygen on a fire to bring out the colour of cold as 

 the other of heat. It is the peculiar virtue of snow that 

 every particle holds air as firmly as does cotton-wool. The 

 corn or grasses that it covers, the animals that it may entomb 

 are not easily affected. The covering lies light, and between 

 and about every crystal pure air clings so that breathing is 

 possible in the medium. Squeeze air out of snow, as its own 

 weight may do, and ice appears. If the snow is very deep 

 and has lain long, the under part is clear, good solid ice. 

 This is the proper relic of an unchanged quality. The 

 attraction of snow is such that we all are inclined to regard 

 it as the characteristic mark of a season. It is of course 



