would lead to the belief, that great changes must take place in the higher lati- 
sree or the prevalence of some cause to detach the ice-islands from the barrier 
in such great quantities as to cover almost the entire section of the ocean, south 
of doe latitude 50° 'S. ‘Taking the early part of the (southern) spring, as the time 
of separation, we are loonie to make some estimate of the velocity we oo 
they move: many masters of vessels have met them, some six or seven dred 
miles from the binsind from sixty to eighty days aitiy: this period, which rae give 
* The season of 1839 and ’40 was considered as an open one, from the Seti 
masses of ice that were met with in a low latitude, by vessels that arrived from 
Europe at Sydney: many of them were seen as far north as latitude 42° 8, | 
The causes that prevail to detach and carry them north, are difficult to assign. 
I have referred to the most probable ones that would detach them from the pa- 
mind that A do phevers + ectttip not, however, look to a surface current as 
being the motive power t at the rate they move ; 
comparatively ufdhiigh their great bulk is below the influence of any surface 
current, and the rapid drift of these masses by winds is still more improbable ; 
therefore I conceive we must look to an under current as their great propeller. 
to occur in the Arctic regions. From this | would draw the conclusion that . 
changes are going on, and it appears to me to be very reasonable to suppose, that 
ried away in the seasons when the polar streams are the strongest, and are borne 
along by them at the velocity with which they move: that these do not occur 
annually may be inferred from the absence of ice-islands in the lower latitudes; 
and that it is not from the scarcity of them, those who shared the dangers of the 
retic cruise, will, I have little doubt, be ready to testify; for, a 
numbers of them studded the ocean that year, as the narrative shows that vast 
numbers of them were left. 
‘The specific gravity of tbe ice varies Bap ta much, as might naturally be ex- 
a for while some o islands are 
n great part composed of a evinpaet blue Aint ice, This. Siferenes i is oceasioned 
by the latter becoming saturated with water, which afterwards free 
“On the ice there was usually a covering of about two feet of saom, which in 
so great a transformation. as not to be recognized. They also appeared to have 
shifted their position with regard to one another, their former bias and trendings 
cane broken u 
During our stzy on the icy coast, I saw nothing of what is termed pack-ice— 
that is, pieces forced one upon the other by the action of the sea or currents.) «* 
wa 2 
‘4 3 elon 
~ 
