Icebergs upon Drift. 445 



been seen at different points off the Cape of Good Hope, 

 between latitudes 36^ and 39^. One seen in those latitudes 

 was two miles in circuniferencej and 150 feet high. They 

 have been seen at the mouth of the Rio de la Plata, in lati- 

 tude 36°. Captain Simpson informs me that he has several 

 times heard of them off Cape Antonio near the same lat- 

 itude. 



These immense masses cannot owe their destruction alone 

 to the melting of their surface by the sun or the heat of the 

 water. Did their dissolution depend alone upon this cause, 

 they might often be transported within the tropics. They 

 seem to contain within themselves a principle of destruction, 

 after they have been subjected to air or water of a certain 

 degree of temperature. Captain William Howland informed 

 me that the icebergs in northern seas, among which he cruised 

 in pursuit of seals, would often founder, as he expressed it, 

 during the summer weather. This foundering was produced 

 by the bursting of the large bergs with a tremendous report, 

 louder than that of a cannon. After the explosion, not a 

 piece of ice larger than a hogshead would be visible. 



Mr. Ichabod Goodwin, a merchant of high standing in 

 Portsmouth, who was formerly a shipmaster, informed me 

 that he was crossing the x\tlantic in the ship Marion, in the 

 month of.May, 1827, when, in latitude 41° 30', and in longi- 

 tude 50^, they passed within a quarter of a mile of an ice- 

 berg which they judged to be about sixty feet high, and over 

 a hundred feet in length. While all hands were below, they 

 heard a report like the discharge of a cannon, and, upon 

 rushing on deck, found that the iceberg had exploded, and 

 had gone completely to pieces. The sea where it just before 

 lay was in considerable agitation. Upon looking with a glass, 

 an hour after, not a particle of ice could be seen. Captain 

 Lake, of Portsmouth, has witnessed the same phenomenon 

 off Labrador. 



This explosion of the iceberg may be attributed to the 

 same cause to which Agassiz attributes the Assuring of the 

 glaciers, namely, the expansion of the air, compressed at the 



