SOUTHWARD 61 
undertaken by Wilson, Bowers and myself in pursuit of 
Emperor penguin eggs—but of that later. 
It is clear that winds and currents are, broadlyspeaking, 
the governing factors of the density of pack-ice. By experi- 
ence we know that clear water may be found in the autumn 
where great tracts of ice barred the way in summer. The 
tendency of the pack is northwards, where the ice melts 
into the warmer waters. But the bergs remain when all 
traces of the pack have disappeared, and, drifting north- 
wards still, form the menace to shipping so well known to 
sailors rounding the Horn, It 1s not hard to imagine that 
one monster ice island of twenty miles in length, such as 
do haunt these seas, drifting into navigated waters and 
calving into hundreds of great bergs as it goes, will in itself 
produce what seamen call a bad year for ice. And the last 
stages of these, when the bergs have degenerated into 
‘srowlers,’ are even worse, for then the sharpest eye can 
hardly distinguish them as they float nearly submerged 
though they have lost but little of their powers of evil. 
There are two main types of Antarctic berg. The first 
and most common is the tabular form. Bergs of this shape 
cruise about in thousands and thousands. A less common 
form is known as the pinnacled berg, and in almost every 
case this is a tabular berg which has been weathered or has 
capsized. The number of bergs which calve direct from a 
mountain glacier into the sea is probably not very great. 
Whence then do they come? 
The origin of the tabular bergs was debated until a 
few years ago. They have been recorded up to forty and 
even fifty miles in length, and they have been called floe 
bergs, because it was supposed that they froze first as 
ordinary sea-ice and increased by subsequent additions 
from below. But now we know that these bergs calve off 
from the Antarctic Barriers, the largest of which is known 
as the Great Ice Barrier, which forms the southern bound- 
ary of the Ross Sea. We were to become very familiar 
with this vast field of ice. We know that its northern face 
is afloat, we guess that it may all be afloat. At any rate the 
open sea now washes against its face at least forty miles 
