AN ANTARCTIC GALK 
141 
depth below the surface is supposed to be three times 
that above. Some of these masses were at least 
900 feet in thickness. Assuming the fall of snow 
to average an inch daily, or 30 feet each year, it 
would require thirty years to form one of these 
blocks, which are found floating here in such 
numbers. 
Their specific gravity varies very much, as might 
naturally be expected ; for while some are of a porous 
and snowy texture, others are in a great measure 
composed of blue flinty ice. This difference is 
occasioned by the latter becoming saturated with 
water from the rain and fogs, which afterwards 
freezes. * * * 
Feb . 23rd .— Clear blue sky and bright sun, weather 
calm and pleasant ; steaming amongst vast numbers 
of magnificent icebergs, some like fairy palaces of 
alabaster, with numerous caverns and arches through 
which the sea dashed its spray. The evening was 
beautifully fine, and a very brilliant sunset illumi- 
nated the horizon, shedding golden rays which were 
again refracted from the pack. We are now within 
20 miles of the position assigned by Wilkes as land, 
but with a clear horizon none was visible. 
Feb. 24 th . — This morning, instead of being able to 
approach the pack, we were in a fearful gale of wind, 
with a heavy and constant fall of snow which com- 
pletely hid the surrounding dangers from us ; for 
being in the vicinity of such vast numbers of bergs 
