Year: 1867




of ordinary ice except that it is froZel


water, for in its structure it is totally dii


ferent When & sheet of ice is for.lel
F. upon the surface by the accumulation q
: little crystals, sometimes rising from tn
bottom, sometimes formed at the yer,
2 surface, and forming an even layer o.
? the whole surface Of the water, an,
r gradually growing in thickness by tn
successive accundIlatiOn Of simila


layers, until the lower temperature o
: the season being exhausted, the water i
covered by a sheet of ice of the thickness
, which the climatic condition of the c0un
try may permit And that ice, wheI
examined carefully, will be found to b.
stratihed, that is, it presents divisions il
: layers which mark the successive stages
! Of frost during the alienation of th'


temperature Of day and night-durina
the alterations of temperature which
are above and below thirty-tWO degrees
/. Fahrenheit. Water freezes only wher
, the temperature falls below, but wheT
frozen, it may be retained ID
large masses when the temperature rise:
above. And so, during these intervals
the lower surface Of the ice which re,
mains on the water may become so mod


flied by air bubbles and by impuritie,
contained in the water, that when a new
layer Of ice is formed underneath, anC
under different conditions of temperature


that the new layer differs from the layer
already formed. And when you exam


inc the ice which is left at your door, OF
brought upon your table, you will set
that even in small pieces there are indi-
cations Of stratification resulting from
the manner in which the ice is formed


Now, glacier ice is totally different, and
the fact that il differs in Its structure SO
much, enables any one familiar with
these differences to recognize these i'm
mense floating icebeTgs which We see on
the Atlantic, and to ascertain that they
are not frozen sea water, but glacier ice
formed on land, advanced into the ocean,
broken from the mass with which they
were attached and then iioated away.
For like glacier ice, all these floating ice
/ bergs show an internal structure totally
different from that of frozen water
formed upon ponds. The difference
J arises from the transformation of the
layers Of snow both by pressure and by
thRwing. These masses of glacier ice are
granular, like a kind of padding stone,
/ cemented together by water frozen into
intervals, and you can readily ascertain
{ that difference Of structure by eXamin-
ing the manner in which these
two kinds of ice melt. It has been
a matter of wonder to seafaTeTs
to find that these immense ice
/ bergs so suddenly disappear, vanish
as it were in a few minutes, while
q mass Of ice formed on water,
which would have these dimensions,
takes a long time to melt, because II
melts at the surface and gradually dimin-
ishes its bulk. But ice from glaciers,
owing TO its peculiar constitution, and to
one remarkable property of ice, which
is its transparency TO heat, will permit
the suns says to penetrate its interior, to
raise simultaneously the temperature Of
all the little intervals which intervene
between the fragments cemented to-
getheT, and then disintegrating in mass,
an immense iceberg may crumble to
pieces and be decompOsed into small
fragments the size of hazel knob or an
egg, and then all the fragments melt
away very rapidly; so that this will
explain the rapid disappearance OF large
cebergs when they have tlOated into
temperate regions, and when they are
affected by the temperature of the lower
latitudes / must call your attention to
that fact of the transparency Of
ice 20 heat, because I shall have
to resort to il to explain





glacier. Suppose we have here a large
fire, and I place between the fire and
myself a large glass screen-a, large pane
Of glass; I shall see through the pane Of
glass, and see the fire and the blaze, but
/ shall not feel the heat, because although
il is Transparent to the light it is Opaque
to the he8t-heat does not readily pass
through glass. Hence it IL that we
make windows Of glass, which interferes
with the change of temperature from
within and without. Take instead Of
such a glass screen a plate OF ice, an ice
screen, and place il between you and the
fire, and you have the same phenOme-
non, as to viewing the light-the blaze
will be seen-but the heat Will pass
through it. A pane of the ice is az
transparent to heat as pane OF glass IS
transparent 10 light. So that through
sheet Of ice on the surface OF a lake,
when the sun shines upon the water, the
stones on the bottom receive heat and
in that manner air bubbles are made to
rise constantly. Through a large mass
Of ice, a rock which is at some depths
under the surface of the ice may be
heated in such manner that in cOnse-
Quence of it the rock may be exposed
and will appear. Suppose that we have
here illustrating by sketches upon the
black board the surface Of the glacier
that we have here the inequalities OF the
bottom over which the glacier moves;
and that here is high rock over which
it passes, the top oft being only twenty,
thirty OF fifty feet below the surface.
That rock will be so heated through
the ice that the ice will melt away
above it, and any materials upon
the surface Of the glacier moving
with it-say a boulder, for instance, or
a large stone which has fallen upon
the surface Of the glacier and which


is carried along with the glacier as IL
moves down, when it comes to this
point, where the glacier is followed by
the operation of the rock below, that
stone will fall upon this point, and will
no longer be carried forward. A glacier
has very different aspects in its diff
ferent parts. Suppose We have here
illustrating by a sketch mountain ine-
qualities, and that there is here deep
valley coming down i'm this way and
that upon these inequalities and noun
tain slopes large masses Of snow have
accumulated. That snow will remain in
its snowy condition az nights, in the
latitude Of 45o for instance, above 5000
feet 50 that everywhere above that
level there is perpetual snow resting
upon the ground. Yet that snow has
not everywhere the same degree of COM
/ pactness and solidity. The lower
il is, the more is it exposed
to the slight changes OF tempe
rature which affect the sides OF
the mountain. The snow will be affected
less at the hight Of 5000 or 5000 feet, and
less and less as we go higher and higher.
/ On ascending some OF the Ice peaks in
ba hfrbaaf in tho Rarnngn
/ Oberland, the Jungfrau, have been able
to trace all these changes Of the atmos-
phere in the ice. At the lower end Of
the glacier, we find that gradually the
ice is more porous, and contains larger
amount Of fragments in a snOw-like
mass and then gradually assumes some
what of the character of a loose and par
tially-cemented snow, aud then gradu-
ally the condition Of pure snOw-no
longer IN the condition of loose and
feathery flakes, but reduced to a cOndi-
ton resembling frozen sand. Such are
the differences in the character OF the
icei and with them arise also differences
in the aspect Of the ice. Snow is white
because Of the large amount of particles
Of air which 1t contains in its crystals.
If we press snow, and expel from
il in that manner the air, We render il





and press il afterward, so that water
NAV replace the air, it loses more and
more OF its white appearance, and be-
comes more transparent. In proportion
as more air is driven away and IS the
ige is freer from all Particles interfering
With the transparency of the mass, the


more does Il assume a greenish or BLUSH
tinge; and finally when il is perfectly
nureaDd perfectly compact, and when
Il has very few fissures through its mass
If assumes a deep blue color, which is
ifs natural color. Water, in its natura


condition, when in large masses, is blue


as gold is yellow, and silver white anc
the ice of the glacier, when i is purest
mas always thai blue appearance
II is not the result Of the reflection
Of the color OF the sky, but II Is u
natural color. And ice has that beauti
! iI bluish tinge, even when the SKY
| Il o,,arcsst or when Il rains heavily