CHAPTER I 



Ice 



We have all seen a pump, and know some- 

 thing about its construction. There is a 

 long leaden pipe which goes down into the 

 well, and above that a short, thick pipe in 

 which the piston rises and falls. This large 

 pipe is the cylinder. 



One very frosty morning we find the 

 cylinder cracked from top to bottom. There 

 is a hole the length of your finger, and a 

 lump of ice projecting through it. How 

 could the cold break this hard iron pipe ? 

 It was not the cold alone. There was some- 

 thing in the cylinder : there was water, and 

 this water was changed into ice, which was 

 imprisoned between the cylinder and the 

 piston, unable to rise or fall. Now ice 

 expands as it forms. It expands to such 

 an extent that, if it happens to be imprisoned, 

 it presses here, there and everywhere, and 

 smashes the obstacle which prevents its 



