MOVEMENT OF THE BARRIER 281 
The barometric gradient probably rises as one goes south, so 
that one cannot use the barometer to obtain accurate levels. 
One could get equal (and useless) readings all the way if 
the change in /evels corresponded to the change in barometric 
gradient. 
In working up the meteorology notes, barometer figures based 
on Royds’ journey—who went nearly parallel to the Barrier edge 
—were unfortunately used to obtain results for the Southern 
Journey. 
Finally, we may conclude that the tendency of all the facts is 
to support the ‘ Floating Barrier’ theory. 
V. Movement of the Barrier—There is certainly not enough 
inclination in the Barrier Ice Sheet to account for its motion. 
The Bay of Whales (or Balloon Bight) has not moved much, 
and this may be taken as the eastern limit of the moving sheet. 
We don’t of course know the extent of the Ice Sheet to the 
south-east. 
Depot A moved 608 yards in thirteen and a half months, 
which agrees closely with the 500 of movement observed by the 
Nimrod. 
We must take note of the direction of movement observed, 
for this may not represent the total movement. It may give the 
minimum, and this result is very startling in view of the sluggish 
land glaciers. 
Simpson suggests that the deposition of snow on the Barrier 
leads to an expansion due to the increase of weight. If it is 350 
miles long and 400 feet thick, then the ratio of thickness to 
length is 1 to 5250. This can be adequately compared to a sheet 
of cardboard ¥% inch thick and the length of this hut (50 feet). 
The ice sheet can only move to the north. If we assume it 
moves 1000 yards, and that 175 square miles is the amount 
moved north, then the mass to be added to keep the breaking 
front about the same position is 11-7 cubic miles. 
Let us consider the snow deposition. It is stated that about 
4 inches of compressed snow falls per year. The blizzards evi- 
dently build up shallow flat hummocks here and there, and may 
cover the whole surface at the fourth effort. 
The old Discovery Depot was covered in 13 inches of old 
snow or g inches of ice. 
