118 THE ICE AGE IN NORTH AMERICA. 



December 25, 1861.— The Queen of Nations fell in with an 

 iceberg in latitude 53° 45' south, longitude 170° 0' west, 720 

 feet high. 



December, 1856. — Captain P. Wakem, ship Ellen Radford, 

 found, in latitude 52° 31' south, longitude 43° 43' west, two 

 large icebergs, one at least 800 feet high. 



Mr. Towson states that one of our most celebrated and 

 talented naval surveyors informed him that he had seen ice- 

 bergs in the southern regions 800 feet high. 



March 23, 1855. — The Agneta passed an iceberg in latitude 

 53° 14' south, longitude 14° 41' east, 960 feet in height. 



August 16, 1840. — The Dutch ship, General Baron von 

 Geen, passed an iceberg 1,000 feet high in latitude 37° 32' south, 

 longitude 14° 10' east. 



May 15, 1859.— The Eose worth found, in latitude 53° 40' 

 south, longitude 123° 17' west, an iceberg as large as "Tristan 

 d'Acunha."* 



Upon these facts Mr, Croll remarks : 



In the regions where most of these icebergs were met with, 

 the mean density of the sea is about 1 -0256. The density of 

 ice is -92. The density of icebergs to that of the sea is there- 

 fore as 1 to 1*115 ; consequently, every foot of ice above water 

 indicates 8*7 feet below water. It therefore follows that those 

 icebergs 400 feet high had 3,480 feet under water — 3,880 feet 

 would consequently be the total thickness of the ice. The 

 icebergs which were 500 feet high would be 4,850 feet thick, 

 those 600 feet high would have a total thickness of 5,820 feet, 

 and those 700 feet high would be no less than 6,790 feet thick, 

 which is more than a mile and a quarter. The iceberg 960 

 feet high, sighted by the Agneta, would be actually 9,312 feet 

 thick, which is upward of a mile and three quarters. 



Although the mass of an iceberg below water compared to 

 that above may be taken to be about 8*7 to 1, yet it would not 

 be always safe to conclude that the thickness of the ice be- 

 low water bears the same proportion to its height above. If 

 the berg, for example, be much broader at its base than at its 



* " Climate and Time," pp. 882-385. 



