67.: 



NATURE 



[February 20, 1913 



To assist in illustration of my meaning' reference 

 must be made to the microthermograin taken on the 

 Allan Line R.M.S. Victorian last June. This record, 

 which is a direct trace from the chart on the instru- 

 ment, is through tlae ice track at a depth of i8 ft. by 

 the Cape Race route. After passing the "Cold Wall" 

 the arctic current drops in temperature regularly as 

 iho ship proceeds westward. The small variations up 

 and down are partly due to icebergs passed at dis- 

 tances of six to eight miles, and partly due to colder 

 currents. The lowest temperature recorded here was 

 reached nearest the Newfoundland coast, but the effect 

 of ice can be seen well marked by the sharp peak of 

 temperature, which I have shaded. Just here we 



proach it. I liavj many other traces illustrating the 

 same thing, and for this reason I was forced to 

 abandon the idea that an iceberg sensibly cools the 

 water in which it is floating. I was also unable to 

 find by calculation that an iceberg could appreciably 

 influence the sea-water on account of its slow rate of 

 melting. 



It is verv illusive to depend on laboratory tank 

 experiments to illustrate sea-water circulation : the 

 conditions at sea are very different. I was very much 

 surprised not to find, during my experiments last 

 summer, more conclusive evidence of sea-water dilu- 

 tion due to the melting icebergs. A large number of 

 conductivitv tests were made of sea-water, and these 



passed most of the ice closely, and were obliged to 

 proceed slowly in heavy fog at times. This colder 

 and swifter arctic current carried with it the greater 

 proportion of the ice, but it is well known that this 

 colder current exists whether accompanied by ice or 

 not. 



The great drop in temperature just before coming 

 abeam of our largest berg was not due to the iceberg 

 itself, but to the influence of the cold current. The 

 effect of the ice is to hold the temperature abnormally 

 high. The dotted line on the diagram represents how 

 the temperature would probably have gone had no ice 

 been present. 



It would depend which way we approached this 

 berg whether a drop in temperature would result. 

 The temperature rises rapidly, whichever wav we ap- 



NO. 2260, VOL. go] 



are described in mv Canadian Government Report. 

 The following may be of interest ; the readings were 

 made at 26° C. : — 



Tabic of Conductivities of Sea-~water taken in Julv 



(1912). 



Close to grounded berg, Cape Bauld Neld 0^05007 



.Strait of Belle Isle, eastern end ... ... 004827 



Ten miles east of Belle Isle 0-04850 



Close abeam large berg... ... ... ..■ 004787 



One mile north of same berg ... ... 004806 



Close abeam same berg ... ... •■• 004827 



Six miles from same berg ... ... ... 004768 



Seventy yards to leeward of a berg ... ... 004787 



Fortv yards to windward of .same berg ... 0-04787 



One hundred yards to leeward of a berg ... 0-04806 



