450 SCOTT'S LAST EXPEDITION 
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 neglecting 
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, 
enclosed 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 accumulate 
a much greater thickness of Barrier on the side farthest 
from the sea. That this is not so is shown by the 
barometric observations 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 
accumulation 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 
