ICEBERGS IN NAVIGATION BARNES. 739 



ciirrenls. Tlie lowest temperature recorded here was reached nearest the Newfound- 

 land coast, but the effect of ice can be seen well marked by the sharp peak of temper- 

 ature, which I have shaded. Just here we passed most of the ice close to 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 haA^e gone had no ice been present. 



It would depend which way we approached this berg whether a drop in tempera- 

 ture would result. The temperature rises rapidl^^, whichever way we approach it. 

 I have manj' 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 very illusive to depend on laboratory tank experiments to illustrate sea water 

 circulation. The conditions at sea are eo veiy different. I was very much surprised 

 not to find during my experiments last summer more conclusive evidence of sea- 

 water dilution due to the melting icebergs. A large number of conductivity tests 

 were made of sea water, and these are described in my Canadian Government report. 

 The following may be of interest; the readings were made at 26° C: 



, Table of conductivities of sea vmter taken in July (1912). 



Close to grounded berg, Cape Bauld, Newfoundland 0. 05007 



Strait of Belle Isle, eastern end 04827 



10 miles east of Belle Isle 04850 



Close abeam large berg 04787 



1 mile north of same berg 04806 



Close abeam same berg 04827 



6 miles from same berg 04768 



70 yards to leeward of a berg 04787 



40 yards to windward of same berg 04787 



100 yards to leeward of a berg 04806 



The numbers may, perhaps, indicate a slight effect, but nothing like what I 

 expected. My conductivity tests of the sea water brought back from Hudsons Strait 

 in 1910 gave a value of 0.0480 at 25° ('. Correcting for temperature this observation 

 serves to connect the sea water entering the Strait of Belle Isle with that in Hudsons 

 Strait. Eastward from Belle Isle Strait the conductivity rises rapidly for ISO milea, 

 after which it becomes uniform up to 450 miles. The greatest Arctic current sweeps 

 down close to the Labrador shore, and in through the Strait of Belle Isle where the 

 resultant flow is westward. The following measurements of the conductivity through 

 the ice track by the Belle Isle route were obtained last October on the Empress of 

 Britain. The values were all measured at a uniform temperature of 25° C. 



Abeam of Belle Isle 0. 04865 



40 miles east of Belle Isle 04986 



80 miles east of Belle Isle 05047 



160miles 05150 



200 miles 05235 



260 miles 05257 



400 miles 05211 



450 miles 05257 



