442 Probable influence of 



motion, with, perhaps, the exception of Captain Barnum, who 

 says that he has seen an iceberg move very slowly on its 

 vertical axis. Captain Wilhani Rowland, who was engaged 

 in the seal fishery in the northern seas, and whose employ- 

 ment led him to land often on the icebergs to procure seals, 

 says that it was impossible that such a motion should have 

 occurred without his observing it. It is a well-known fact, 

 that the Greenland whalers and sealers move their vessels to 

 the floating icebergs, to protect themselves from the drift ice. 

 According to this evidence, some other cause must be sought 

 for the formation of the bowl-shaped cavities which occur in 

 the drift, than the rotatory or semi-rotatory movement of ice- 

 bergs. 



The only remarkable movement which has been observed 

 in floating icebergs is that occasioned by their overturn. 

 This phenomenon has been noticed by all observers. The 

 falling of portions of the mass, which is called the calving of 

 the iceberg, or the wasting of the lower portions by warm 

 water, destroys the equilibrium of the berg, and causes it 

 either to overturn entirely, or so far as to bring a new surface 

 to view. Although, from the descriptions which are given, 

 the overturn of a huge iceberg in a calm sea, while the sun 

 is shining upon its glittering peaks, with all the circumstances 

 of the crushing of the fractured ice, the foaming and rolling 

 of the disturbed water, the sudden change in the form and 

 outline of the mighty mass, must form a scene of surpassing 

 grandeur, the only eflect which has interest in our inquiries 

 is the production of enormous waves, equalling or surpassing 

 those produced by the fall of ice, which are said to be so 

 heavy as to endanger boats at the distance of several miles, 

 and, in a perfect calm, to have dashed over the bows of a 

 vessel of forty tons, at a distance of five miles. By this 

 agency, Scoresby says, fields of ice are often broken up ; and 

 by the same agency the stranded bergs might be lifted up, 

 and urged along the bottom upon which they are grounded. 



Icebergs are often seen aground in great depths of water. 

 1 have already mentioned those seen aground by Ross in 



