THE BARRIER 
449 
about |. From the same authorities we know that the 
yearly motion is in an east-north-easterly direction (close 
to Minna Bluff) at the rate of about 500 yards a year. 
We have, moreover, data to show that no great change 
in the position of the seaward edge of the Barrier has 
taken place since the Discovery Expedition in 1901-04. 
Thus the Barrier may be considered for purposes of 
calculation as remaining in statu quo by virtue of the 
discharge of icebergs from its seaward face. 
If this is so, we see that the volume of ice due to deposi- 
tion, ^ X iV X i X 400 X 2000 X 300 X 2000 = 12 X 10^*^ 
cubic yards (taking width as 400 miles, and length 300), 
should be converted into a strip of ice on the seaward 
side 400 miles long, 500 yards wide, and 600 feet deep 
== 8 X IQ-^^ cubic yards. 
This agreement of observation is a remarkably close 
one and proves that our fundamental statement is very 
close to the truth. 
It should here be pointed out that in the above 
calculation no allowance has been made for the effect of 
glaciers pushing the Barrier before them and so adding 
to the apparent motion. That is, it is assumed the 
Barrier moves under its own weight alone. Luckily the 
Barrier may be subjected to further calculation, being 
in the happy position of a mass of ice resting on a friction- 
less plane at freezing point. Thus with certain assumptions 
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 
VOL. 11. 2 G 
