IV.] 



SNOW AND ICE. 



63 



what is called sleet. The largest snow-flakes fall when the 

 temperature is near the freezing-point, and the smallest 

 when the temperature is very low. It need hardly be 

 said that snow is much lighter than rain ; it is usually 

 estimated at about one-tenth the weight of an equal bulk 

 of water, so that if a fall of snow lies on the ground to 



Fig. 17. — Ice-flowers. 



the depth of ten inches, it may be taken roughly to 

 represent one inch of rain : it is obvious, however, that 

 snow varies much in its state of compactness, and this 

 method is consequently, in many cases, far from accurate. 

 The loose texture of snow renders it an extremely 

 "bad conductor of heat, and a fall of snow thus acts like 

 a mantle of fur thrown over the earth. The air entangled 



