AMONGST THE SOUTHERN ICE. 233 



in a latitude nearly corresponding to that of the Shetland Islands 

 and Christiania in Norway, in the northern hemisphere. 



The temperature gradually fell as we went southwards, and 

 on February 9th went down for the first time to just below 

 freezing point in a snow squall. 



At first, all the icebergs seen were numbered each day, and 

 their positions noted down ; but when we came to have 40 in 

 sight at once this plan was abandoned, and w r e subsequently had 

 more than a hundred in sight on several occasions. 



The typical form of the Antarctic iceberg, as seen above 

 water, and apparently the form which it always has when first 

 set free on its wanderings, is very simple. The top is a nearly 

 flat expanse of snow, and this is bounded all around by per- 

 pendicular cliffs. The boundary lines of the expanse are no 

 doubt always in the first instance nearly straight lines, since 

 they must be produced by the splitting off of the berg from the 

 parent mass, and the previous splitting of similar bergs from its 

 own outer border when still attached. 



A considerable number of the undecayed bergs seen by us 

 were almost rectangular in outline. Some few were irregularly 

 oval, and the weathered ones of course of all possible irregular 

 outlines. 



Since ice requires about 

 nine times its volume to be 

 immersed in order to float 

 it above sea water, the por- 

 tion of an iceberg which 

 shows above water is a verv 

 small proportionate part of 

 the mass. Mr. Buchanan 



DIAGRAM TO SHOW THE PROPORTION OF AN ICEBERG 



made an accurate estimate immersed, and above water. 



of the specific gravity of samples of the berg ice, and calculation 

 of amount of immersion of icebergs. The proportionate depth 

 of a berg below water will of course depend on the form and on 

 the relative density of the upper and lower strata of the mass. 

 Usually, no doubt, the mass below water is far less than nine 

 times the vertical depth of the height of the part above water, 

 from two considerations. Firstly, the sides of the berg are not 



