ICEBERGS 



IN many cases, icebergs are of immense size, and they are 

 always slowly melting. Many have supposed that it would 

 be possible to detect their presence by a change in the tem- 

 perature of the water, but nothing could be farther from the 

 truth. 



At the spot where the Titanic went down the water is 

 over two miles in depth. Water, being a non-conductor 

 of heat, can only be cooled or heated by convection that 

 is, in order to be cooled it must touch something that is 

 cold. About eight-ninths of the bulk of an iceberg is below 

 the surface of the water, and only one-ninth above. As the 

 sea water comes in contact with the ice, a certain portion 

 of the ice is dissolved, and each pound of it that is dissolved 

 absorbs heat enough from the surrounding sea water to 

 raise one pound of water 140 that is, it requires 140 

 British thermal units to melt one pound of ice. This is 

 very considerable, and causes a downward current of the 

 sea water and what little fresh water has been melted from 

 the ice, so that with a large iceberg the relatively warm 

 water of the sea is flowing from all sides towards the ice- 

 berg, and as it comes in contact, it is cooled, sinks, and other 

 water is drawn into its place. Thus the iceberg is constantly 

 being diminished in size, but it does not chill the surface of the 

 water to any considerable extent. If the water about an 



43 



