ICEBERGS 309 
alone. Luckily the Barrier may be subjected to further calcula- 
tion, being in the happy position of a mass of ice resting on a 
frictionless plane at freezing-point. Thus with certain assump- 
tions regarding the rather uncertain coefficient of viscosity of ice 
and a slight excursion into integral calculus, we can arrive at the 
conclusion that the Barrier under its own weight would each 
year push out a distance of from 100 to 500 yards,—a distance 
at least of the same order of magnitude as that found by 
observation. 
From this we see we are probably justified in neclecting the 
volume of ice added to the Barrier and carried down by glaciers 
from the plateau and may treat the Barrier as an entity by itself. 
Consider now the effect of such a Barrier in equilibrium, en- 
closed on three sides and exposed to a continuous snowfall. 
Without any further mathematics it is at once clear that the 
velocity of motion at the seaward edge must be very many times 
faster than the velocity at the shore farthest from the sea. The 
tendency of a continuous snowfall would be therefore to accumu- 
late a much greater thickness of Barrier on the side farthest from 
the sea. That this is not so, is shown by the barometric observa- 
tions of the sledging parties, which furnish convincing proof that 
the Barrier is still afloat quite close to the landward end, and 
further that a very good current circulation obtains under this 
part, since the single circumstance capable of preventing an accu- 
mulation of snow, is a corresponding melting action, which again 
can only be due to water underneath the Barrier. 
ICEBERGS 
It has been noted that the Barrier and also land-glaciers may 
discharge ice into the sea in the form of bergs. Since no bergs 
were ever seen in McMurdo Sound except in the late summer 
months it may almost be taken that the prime cause of the calv- 
ing of bergs from the parent glacier is due to the melting action 
of the warm sea water. 
Bergs met with in the Antarctic can best be roughly divided 
into barrier or tabular bergs and glacier bergs. The tabular berg 
is recognised by its flat tabular form, whereas the glacier berg 
seldom has such a regular profile and often is formed of deep 
blue ice in contradistinction to the dazzling whiteness of the 
