The Sunday herald. [volume] (Washington [D.C.]) 1866-1887, 1880-05-09

evidence In the constant maintenance Of tho glacial
temperature, not only Of the bottom, hut Of the
great mass Of the water contained the vast oceanic
basin, cannot I've maintained without continual IN
draught OF the upper stratum toward the roles this,
Its temperature Is progressively lowered, decreases
In volume and increases In specific gravity; and the
lower stratum flows away under the Of PRESSURE
the upper stratum, nov cooled down nearly to the
freezing point Of salt water win sink into Its place,
making way for new indraught above. The two
Polar undernows, on the other hand, meeting at or
near the Equator, win there tend 10 rise toward the
surface replacing the water which has been draughtc
away toward either pole: and thus constant "Verti-
cal circulation" must he kept up by opposition OF
temperature alone analogous to that which takes place
in the pipes Of a ho-watcr apparatus by which large
buildings are commonly warmed The only essential
difference between the two cases Is that whilst the
prfna mobile In the latter Is the heat applied to the
bottom Of the boiler, making the warmed water
ascend by the reduction OF the specific gravity
due TO Its expansion, the moving power IN the
former Is the cold applied to the surface NJ tho Polar
water making descend by the increase OF specific
gravity due to the dlmiutinn Of Its bulk rs It's tenn
| pcrature Is lowered. As tho supetheaing of
the upper stratum Of the mid Atlantic Is dependent ON
the influx of Gulf stream and other water exception
ally warmed In the Equatorial Current the thermal
cftct OF It's Me-. now Il mainly dependent upon the
Gulf Stream and It's aiiuncts while Its Increment Is
kcII UP ny lUe lNliI lnulduHnlS linus nCllncI tne
general oceanic circulation the Gulf stream could
alone produce the result which Is due to their conon,
action. The Gulf stream waters without the Polar
inlfaught, would remain In the the mid Atlantic;
| and the roar indrnught, without Gulf stream water
| to feed II would lie almost destitute Of thermal
| power rs IT Is In the South Atlantic.
The Antarctic icebcrgs afford interest.
ing indications of the nature of the region
in which they originate. They differ totally
in character from those of the Arctic region
which are the broken-ofi ends of the glacier;
that have descended the seaward valleys %
Greenland and Labrador. The Antarcti,
bcrgs, on the other hand, are mostly de
tached portions ot vast jce-Shoci coverin!
the Antarctic continent which is nearl,
double the area of Australia. "Of this ice
sheet the edge forms the great Southeri
''' ice-barrier, which presents itself where
lever it has been approached sufficiently
near to be distinctly visible, as n contuu
g Gus ice-clin, rising from two hundred I
1.-TWO hundred and fifty feet above the Sc
level The icebcrgs thrown oil from thi
mass are estimated TO average two thousan
feet in height, of which about two hundre
, feet project above the sea level. The dimer
sions of these bergs vary greatly. Those see
from the Challenger were generally froi
| one to three milrs lonc. Lut einula bnrre a,
, -,
, 'efoi'e" WI Sc'ch VI wv" 'ch iiiicS
, | length, and an enormous mass of iloatin
ira nrobobIv rnmnosaJ of , chain or ba,c
locked together, forming hook sixty mile
long by forty broad and enclosing n ba