338 GLACIERS AND ICEBERGS. 



solid rock ! lie calculated that a cube of ice, forty feet 

 across the side, could easily have carried ofl' this burden 

 in water seven fathoms deep. Icebergs thus broken off 

 from the parent glacier were often observed tumbling 

 about in the sea. Some of these were four times bigger 

 than St. Paul's Cathedral, and shrouded themselves in 

 a veil of spray as they rolled over, emitting sounds that 

 could only be compared to terrific thunder-peals, and 

 turning up the blue mud from depths of two and three 

 hundred fathoms. Oscillations in the sea were pro- 

 duced by such disturbances, which, after travelling a 

 dozen miles, pounded into fragments the ice-field on 

 which they ultimately fell. 



While icebergs are the slow growth of ages, the 

 fields or shoals of saline ice are annually formed and 

 destroyed. The ice generated from melted snow is 

 hard, pellucid, and often swells to an enormous height 

 and dimensions. But the concretion of salt water wants 

 solidity, clearness, and strength, and never attains to 

 any very considerable thickness. It seldom floats dur- 

 ing more than part of the year ; though, in some cold 

 seasons, the scattered fragments may be surprised by 

 the early frost, and preserved till the following summer. 



Captain Penny's expedition reached the entrance of 

 Wellington Channel on the 25th of August. On the 

 14th of September young ice formed round the ships ; 

 and they were compelled to take up their winter quar- 

 ters in Assistance Bay, near the south-west point of 

 Wellington Channel. Captain Austin's squadron, of 

 four ships, was fixed on Griffith's Island, a few miles 

 further west. November 7th, the sun was beneath the 

 horizon at noon, the thermometer was seven degrees 

 below zero, and the sea-ice three feet thick. January 

 13th, mercury froze for the first time. .At the end of 

 January the ice was five feet thick. The sun rose 



