ICEBERGS IN NAVIGATION BARNES. 737 



chemical department by Dr. Mcintosh and Mr. Otto Maass. No possible error could 

 result in this way, and the tests being carried out at a constant temperature under the 

 most favorable circumstances there is no reason to doubt their correctness. The 

 comparison shows little dilution due to the icebergs, which goes to show how quickly 

 the melted water from the berg is mixed with the sea water. Larger variations were 

 found at different partvS of the sea than were obtained in the proximity of ice. 



It is evident that an iceberg in melting causes only two of the Pettersson currents, 

 i. e., a cold current which sinks downward carrying with it most of the melted ice 

 water, and a horizontal surface current of sea water flowing in toward the ice to cause 

 its melting. By this means we should expect the sea in the immediate proximity of 

 cebergs to be warmer than further away, because the sea surface current is moving 

 in toward the berg and does not share in the normal vertical circulation which tends 

 to keep the sea surface temperature cooler. 



The iceberg, in causing its own current of warmer water, provides for its own disin- 

 tegi-ation. Abundant evidence is at hand to show the melting process going on under 

 the water line. 



In my observations of icebergs I was greatly struck with the large amount of air 

 dissolved in the ice. The white color of the berg is due to innumerable air bubbles 

 in the ice, and not to snow on the surface. An iceberg is very deceptive in this way. 

 While it looks quite soft, the ice is so hard as to make it difficult to chop with an ax. 

 Ice water which I prepared for drinking on board ship with iceberg ice appeared to 

 effervesce like soda water, merely due to the liberation of the air from the melting ice. 

 It is possible that the sudden disappearance of bergs with a loud report is due to their 

 explosion from accvunulated air in the interior. I passed close to one berg which was 

 casting off small pieces, apparently by the pressure of the pent-up air. 



While icebergs send the temperature of the sea up, land and coast line send it 

 down. This was observed all along the coast in the Straits of Belle Isle. This effect 

 is due to the action of land in turning up the colder underwater by the action of tides 

 and currents. A great deal of work remains to be done in studying the effect of land 

 and shoals on the temperature of the sea, but observations show the effect not only 

 here but on the Irish and English coasts. 



From the point of view of the safety of our St. Lawrence route, the effect of land is 

 most important. The iceberg causes us little worrj'^ because we have only a very 

 hort ice track, but to find means whereby the proximity of land can be determined 



of the greatest importance. 



APPENDIX 2. 



Letter to "Nature" on iceberg melting. 



Editor Nature: I have pleasure in sending you a photograph of the iceberg around 

 which we obtained the isothermal lines published in the issue of Nature for Dec. 12 

 (pi. 2, fig. 1). I did not make an instrumental survey of this berg, but it was larger 

 tlian the average of those met with in the Strait of Belle Isle. We sighted over 200 

 bergs during our trip and made traces of many of them. Invariiibly the temperature 

 rose on the approach to a berg. Sometimes a small fall of temperature resulted abeam 

 of the berg, but the rise of temperature was the one cliaracterLstic effect. The two 

 other photographs illustrate the fantastic shapes seen in ice (pi. 2, fig. 1; pi. 3). I 

 wish it were possible to furnish in some way an idea of the wonderful coloring, but 

 I am totally unable to do so. 



