78 THE ROYAL SOCIETY OF CANADA 



ordinary thermal convection effects, and that in working out any satis- 

 factory theory of ocean circulation, we must fully consider these 

 facts. 



Relation of Iceberg Melting to the Stratum of Low 

 Temperature. 



Dr. Pettersson has given us some idea of the enormous forces 

 operating in the melting of the polar ice. He says: — 



"To melt an ice-field in the northern seas, it is necessary that 

 at least seventeen times its weight in salt water should be cooled 

 and sunk to the bottom. The sinking of this cold water resembles 

 a waterfall more than 1,000 metres in height. Like any waterfall 

 on the earth's surface, this submarine fall can produce work, that is 

 can work the deep currents in the ocean. It is the power of this 

 water-fall that presses up the wall of cold water north of the Iceland- 

 Faroe ridge, as it is the sinking cooled water in the southern ice sea 

 and at Newfoundland that builds up the cold water mountains under 

 the equator and along the coasts of Africa and America. To the ques- 

 tion what becomes of all the sinking cooled water ? our answer as 

 far as regards the Norwegian and polar sea, is it overflows the rim 

 of the Faroe-Iceland ridge, and sinks to the bottom of the ocean, 

 making a fall of almost ice-cold water 400 or 500 metres below the sur- 

 face. The question, what becomes of this water in the ocean ? must 

 be left to future investigation. 



"The sinking of the cooled water whose store of heat has been 

 expended in melting the ice is identical with a water-fall, the effects 

 of which are recognizable in the movement of the bottom layers 

 and submarine currents. The second movement of the ice-melting, 

 i.e., the rising of the melted ice-water to the surface, may also be likened 

 to a water-fall, though in inverse direction, for here the water is lifted 

 from below to the surface. This, too, is a production of labour which 

 is useful in the oceanic circulation, i.e., for working the surface currents 

 of the sea, for instance, the polar current. I have estimated the labour 

 thus produced during the ice-melting in summer between Iceland 

 and Jan Mayen, as equal to the work produced by a water-fall on the 

 earth's surface of about 400,000 h.p. These figures represent the 

 energy which drives the water of the East Iceland polar current 

 towards the Faroes. Incomparably greater is the energy produced 

 by the melting of the Atlantic icebergs in the south polar sea. There 

 the melted ice-water rises from a far greater depth, from the under- 

 most side of icebergs 200 to 500 metres below the surface. As the effect 

 of a water-fall is proportionate to the height from which it falls, 



