[barnes] ISOTHERMAL LAYER OF LOW TEMPERATURE 79 



it is easy to estimate that every kilogram of ice melted in this depth 

 will produce an energy equal to 7 kilogrammetres. 



"An iceberg floating in the sea contains in itself such a possibility 

 for work. It produces a depression in the surface which would be 

 eliminated the moment the ice was taken away. The surrounding 

 water strives to assume a horizontal surface by eliminating the de- 

 pression occupied by the ice. The water presses the ice upwards, 

 but as long as the ice forms a solid block, its effects are in vain. The 

 weight of the ice equals the lifting power of the water, which power 

 is localized in the very surface of contact between the ice and the water, 

 but which is unable to produce labour. If heat is brought from out- 

 side melting the ice, its molecules will become moveable and lifted 

 up to the surface where the melted ice-water flows out, in the shape 

 of a surface current. This then, is work, by setting free the forces 

 that were tied in the contact surface between the ice and sea-water." 



What becomes of the current of cooled sea-water which sinks 

 under the influence of the melting iceberg ? This water is drawn 

 from the surface of the sea, where the density is less than at a greater 

 depth. It is cooled, presumably to approximately 30°F. If by this 

 means its density is increased by means of the temperature fall, 

 beyond that of the surrounding sea-water, it will sink. The process 

 of fall must stop, however, by the time the water has reached the 

 lower limit of the cooling agent. At approximately 30 or 40 fathoms, 

 the cooled sea-water finds itself reduced to 30°F. or thereabout, 

 but of less density than the lower layers of sea-water. There will 

 then be no tendency for the water to sink lower, even though the tem- 

 perature increases a little at greater depths. There will be no agent 

 at work to make this water rise because it gains heat only exceedingly 

 slowly from below, and it is unaffected by the disturbing influence 

 of the waves on the surface. In the course of ages it is conceivable 

 that a cold layer of water produced by the melting of the icebergs, 

 has under-spread the whole polar current, even into the Gulf of St. Law- 

 rence itself. Constantly fed each year by the masses of ice, this cold 

 layer maintains a fairly equal temperature the year round. From 

 Dr. Dawson's measurements, it looks as though a higher temperature 

 existed in the cold stratum early in the spring when the water was 

 coldest, and before the icebergs have begun to melt rapidly. Thus 

 he found in May, 1903, that at 30 fathoms, the temperature off the 

 South East Coast of Newfoundland was from 32 to 35-5°F, whereas 

 on the 11th of August of the same year, the temperature was found 

 to be 31° at the same depth and place. Further measurements are 

 required to establish beyond doubt the connection between iceberg 



