The South Pole, Volumes 1 and 2 by Roald Amundsen

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The variation of the compass at the first Polar station was determined
by a series of bearings of the sun. This gives us the absolute
direction of the last day's line of route. The length of this line
was measured as five and a half geographical miles. With the help of
this we are able to construct for Polheim a field of the same form
and extent as that within which the first Polar station must lie.

At Polheim, during a period of twenty-four hours (December 16 --
17), observations were taken every hour with one of the sextants. The
observations show an upper culmination altitude of 28deg. 19.2', and a
resulting lower culmination altitude of 23deg. 174'. These combining the
above two altitudes, an equal error on the same side in each will
have no influence on the result. The combination gives a latitude
of 89deg. 58.6'. That this result must be nearly correct is confirmed
by the considerable displacement of the periods of culmination
which is indicated by the series of observations, and which in the
immediate neighbourhood of the Pole is caused by the change in the
sun's declination. On the day of the observations this displacement
amounted to thirty minutes in 89deg. 57', forty-six minutes in 89deg. 58',
and over an hour and a half in 89deg. 59'. The upper culmination occurred
so much too late, and the lower culmination so much too early. The
interval between these two periods was thus diminished by double the
amount of the displacements given. Now the series of observations
shows that the interval between the upper and the lower culmination
amounted at the most to eleven hours; the displacement of the periods
of culmination was thus at least half an hour. It results that Polheim
must lie south of 89deg. 57', while at the same time we may assume that
it cannot lie south of 89deg. 59'. The moments of culmination could,
of course, only be determined very approximately, and in the same way
the observations as a whole are unserviceable for the determination
of longitude. It may, however, be stated with some certainty that
the longitude must be between 30deg. and 75deg. E. The latitude, as already
mentioned, is between 89deg. 57' and 89deg. 59', and the probable position
of Polheim may be given roughly as lat. 89deg. 58.5' S., and long. 60deg. E.

On the accompanying sketch-chart the letters abcd indicate the field
within which the first Polar station must lie; ABCD is the field which
is thereby assigned to Polheim; EFGH the field within which Polheim
must lie according to the observations taken on the spot itself; P
the probable position of Polheim, and L the resulting position of the
first Polar station. The position thus assigned to the latter agrees as
well as could be expected with the average result of the observations
of December 15. According to this, Polheim would be assumed to lie
one and a half geographical miles, or barely three kilometres, from
the South Pole, and certainly not so much as six kilometres from it.

From your verbal statement I learn that Helmer Hanssen and Bjaaland
walked four geographical miles from Polheim in the direction taken to
be south on the basis of the observations. On the chart the letters
efgh give the field within which the termination of their line of route
must lie. It will be seen from this that they passed the South Pole
at a distance which, on the one hand, can hardly have been so great
as two and a half kilometres, and on the other, hardly so great as two
kilometres; that, if the assumed position of Polheim be correct, they
passed the actual Pole at a distance of between 400 and 600 metres;
and that it is very probable that they passed the actual Pole at a
distance of a few hundred metres, perhaps even less.

I am, etc.,

(Signed) Anton Alexander.

Christiania,

September 22, 1912.

CHAPTER V

Oceanography

Remarks of the Oceanographical Investigation carried out by the "Fram"
in the North Atlantic in 1910 and in the South Atlantic in 1911. By
Professor Bjorn Helland-Hansen and Professor Fridtjof Nansen

In the earliest ages of the human race the sea formed an absolute
barrier. Men looked out upon its immense surface, now calm and
bright, now lashed by storms, and always mysteriously attractive;
but they could not grapple with it. Then they learned to make boats;
at first small, simple craft, which could only be used when the sea
was calm. But by degrees the boats were made larger and more perfect,
so that they could venture farther out and weather a storm if it
came. In antiquity the peoples of Europe accomplished the navigation
of the Mediterranean, and the boldest maritime nation was able to
sail round Africa and find the way to India by sea. Then came voyages
to the northern waters of Europe, and far back in the Middle Ages
enterprising seamen crossed from Norway to Iceland and Greenland and
the north-eastern part of North America. They sailed straight across
the North Atlantic, and were thus the true discoverers of that ocean.

Even in antiquity the Greek geographers had assumed that the greater
part of the globe was covered by sea, but it was not till the beginning
of the modern age that any at all accurate idea arose of the extent of
the earth's great masses of water. The knowledge of the ocean advanced
with more rapid steps than ever before. At first this knowledge
only extended to the surface, the comparative area of oceans, their
principal currents, and the general distribution of temperature. In
the middle of the last century Maury collected all that was known,
and drew charts of the currents and winds for the assistance of
navigation. This was the beginning of the scientific study of the
oceanic waters; at that time the conditions below the surface were
still little known. A few investigations, some of them valuable, had
been made of the sea fauna, even at great depths, but very little
had been done towards investigating the physical conditions. It
was seen, however, that there was here a great field for research,
and that there were great and important problems to be solved; and
then, half a century ago, the great scientific expeditions began,
which have brought an entire new world to our knowledge.

It is only forty years since the Challenger sailed on the first
great exploration of the oceans. Although during these forty years
a quantity of oceanographical observations has been collected with a
constant improvement of methods, it is, nevertheless, clear that our
knowledge of the ocean is still only in the preliminary stage. The
ocean has an area twice as great as that of the dry land, and it
occupies a space thirteen times as great as that occupied by the
land above sea-level. Apart from the great number of soundings for
depth alone, the number of oceanographical stations -- with a series
of physical and biological observations at various depths -- is very
small in proportion to the vast masses of water; and there are still
extensive regions of the ocean of the conditions of which we have
only a suspicion, but no certain knowledge. This applies also to the
Atlantic Ocean, and especially to the South Atlantic.

Scientific exploration of the ocean has several objects. It seeks to
explain the conditions governing a great and important part of our
earth, and to discover the laws that control the immense masses of
water in the ocean. It aims at acquiring a knowledge of its varied
fauna and flora, and of the relations between this infinity of
organisms and the medium in which they live. These were the principal
problems for the solution of which the voyage of the Challenger and
other scientific expeditions were undertaken. Maury's leading object
was to explain the conditions that are of practical importance to
navigation; his investigations were, in the first instance, applied
to utilitarian needs.

But the physical investigation of the ocean has yet another very
important bearing. The difference between a sea climate and a
continental climate has long been understood; it has long been known
that the sea has an equalizing effect on the temperature of the air,
so that in countries lying near the sea there is not so great a
difference between the heat of summer and the cold of winter as on
continents far from the sea-coast. It has also long been understood
that the warm currents produce a comparatively mild climate in high
latitudes, and that the cold currents coming from the Polar regions
produce a low temperature. It has been known for centuries that the
northern arm of the Gulf Stream makes Northern Europe as habitable
as it is, and that the Polar currents on the shores of Greenland and
Labrador prevent any richer development of civilization in these
regions. But it is only recently that modern investigation of the
ocean has begun to show the intimate interaction between sea and
air; an interaction which makes it probable that we shall be able to
forecast the main variations in climate from year to year, as soon
as we have a sufficiently large material in the shape of soundings.

In order to provide new oceanographical material by modern methods,
the plan of the Fram expedition included the making of a number of
investigations in the Atlantic Ocean. In June, 1910, the Fram went
on a trial cruise in the North Atlantic to the west of the British
Isles. Altogether twenty-five stations were taken in this region
during June and July before the Fram's final departure from Norway.

The expedition then went direct to the Antarctic and landed the shore
party on the Barrier. Neither on this trip nor on the Fram's subsequent
voyage to Buenos Aires were any investigations worth mentioning made,
as time was too short; but in June, 1911, Captain Nilsen took the
Fram on a cruise in the South Atlantic and made in all sixty valuable
stations along two lines between South America and Africa.

An exhaustive working out of the very considerable material collected
on these voyages has not yet been possible. We shall here only attempt
to set forth the most conspicuous results shown by a preliminary
examination.

Besides the meteorological observations and the collection of
plankton -- in fine silk tow-nets -- the investigations consisted
of taking temperatures and samples of water at different depths The
temperatures below the surface were ascertained by the best modern
reversing thermometers (Richter's); these thermometers are capable
of giving the temperature to within a few hundredths of a degree at
any depth. Samples of water were taken for the most part with Ekman's
reversing water-sampler; it consists of a brass tube, with a valve at
each end. When it is lowered the valves are open, so that the water
passes freely through the tube. When the apparatus has reached the
depth from which a sample is to be taken, a small slipping sinker
is sent down along the line. When the sinker strikes the sampler,
it displaces a small pin, which holds the brass tube in the position
in which the valves remain open. The tube then swings over, and this
closes the valves, so that the tube is filled with a hermetically
enclosed sample of water. These water samples were put into small
bottles, which were afterwards sent to Bergen, where the salinity of
each sample was determined. On the first cruise, in June and July,
1910, the observations on board were carried out by Mr. Adolf Schroer,
besides the permanent members of the expedition. The observations
in the South Atlantic in the following year were for the most part
carried out by Lieutenant Gjertsen and Kutschin.

The Atlantic Ocean is traversed by a series of main currents, which
are of great importance on account of their powerful influence
on the physical conditions of the surrounding regions of sea and
atmosphere. By its oceanographical investigations in 1910 and 1911
the Fram expedition has made important contributions to our knowledge
of many of these currents. We shall first speak of the investigations
in the North Atlantic in 1910, and afterwards of those in the South
Atlantic in 1911.

Investigations in the North Atlantic in June and July, 1910.

The waters of the Northern Atlantic Ocean, to the north of lats. 80deg.
and 40deg. N., are to a great extent in drifting motion north-eastward
and eastward from the American to the European side. This drift is
what is popularly called the Gulf Stream. To the west of the Bay
of Biscay the eastward flow of water divides into two branches, one
going south-eastward and southward, which is continued in the Canary
Current, and the other going north-eastward and northward outside
the British Isles, which sends comparatively warm streams of water
both in the direction of Iceland and past the Shetlands and Faroes
into the Norwegian Sea and north-eastward along the west coast of
Norway. This last arm of the Gulf Stream in the Norwegian Sea has
been well explored during the last ten or fifteen years; its course
and extent have been charted, and it has been shown to be subject to
great variations from year to year, which again appear to be closely
connected with variations in the development and habitat of several
important species of fish, such as cod, coal-fish, haddock, etc., as
well as with variations in the winter climate of Norway, the crops,
and other important conditions. By closely following the changes in
the Gulf Stream from year to year, it looks as if we should be able
to predict a long time in advance any great changes in the cod and
haddock fisheries in the North Sea, as well as variations in the
winter climate of North-Western Europe.

But the cause or causes of these variations in the Gulf Stream are at
present unknown. In order to solve this difficult question we must be
acquainted with the conditions in those regions of the Atlantic itself
through which this mighty ocean current flows, before it sends its
waters into the Norwegian Sea. But here we are met by the difficulty
that the investigations that have been made hitherto are extremely
inadequate and deficient; indeed, we have no accurate

(Fig. 1. -- Hypothetical Representation of the Surface Currents in
the Northern Atlantic in April.

After Nansen, in the Internationale Revue der gesamten Hydrobiologie
and Hydrographie, 1912.)

knowledge even of the course and extent of the current in this ocean. A
thorough investigation of it with the improved methods of our time
is therefore an inevitable necessity.

As the Gulf Stream is of so great importance to Northern Europe in
general, but especially to us Norwegians, it was not a mere accident
that three separate expeditions left Norway in the same year, 1910 --
Murray and Hjort's expedition in the Michael Sars, Amundsen's trial
trip in the Fram, and Nansen's voyage in the gunboat Frithjof --
all with the object of investigating the conditions in the North
Atlantic. The fact that on these three voyages observations were
made approximately at the same time in different parts of the
ocean increases their value in a great degree, since they can thus
be directly compared; we are thus able to obtain, for instance,
a reliable survey of the distribution of temperature and salinity,
and to draw important conclusions as to the extent of the currents
and the motion of the masses of water.

Amundsen's trial trip in the Fram and Nansen's voyage in the Frithjof
were made with the special object of studying the Gulf Stream in
the ocean to the west of the British Isles, and by the help of these
investigations it is now possible to chart the current and the extent
of the various volumes of water at different depths in this region
at that time.

A series of stations taken within the same region during Murray
and Hjort's expedition completes the survey, and provides valuable
material for comparison.

After sailing from Norway over the North Sea, the Fram passed through
the English Channel in June, 1910, and the first station was taken on
June 20, to the south of Ireland, in lat. 50deg. 50' N. and long. 10deg.
15' W., after which thirteen stations were taken to the westward,
to lat. 58deg. 16' N. and long. 17deg. 50' W., where the ship was on June
27. Her course then went in a northerly direction to lat. 57deg. 59'
N. and long. 15deg. 8' W., from which point a section of eleven stations
(Nos. 15 -- 25) was made straight across the Gulf Stream to the bank
on the north of Scotland, in lat. 59deg. 88' N. and long. 4deg. 44' W. The
voyage and the stations are represented in Fig. 2. Temperatures and
samples of water were taken at all the twenty-four stations at the
following depths: surface, 5, 10, 20, 30, 40, 50, 75, 100, 150, 200,
300, 400, and 500 metres (2.7, 5.4, 10.9, 16.3, 21.8, 27.2, 40.8,
54.5, 81.7, 109, 163.5, 218, and 272.5 fathoms) -- or less, where
the depth was not so great.

The Fram's southerly section, from Station 1 to 13 (see Fig. 3)
is divided into two parts at Station 10, on the Porcupine Bank,
south-west of Ireland. The eastern part, between Stations 1 and 10,
extends over to the bank south of Ireland, while the three stations
of the western part lie in the deep sea west of the Porcupine Bank.

[Fig. 2 and caption: Fig. 2. -- The "Fram's" Route from June 20
to July 7, 1910 (given in an unbroken line -- the figures denote
the stations).

The dotted line gives the Frithjof's route, and the squares give five
of the Michael Sars's stations.]

In both parts of this section there are, as shown in Fig. 3, two great
volumes of water, from the surface down to depths greater than 500
metres, which have salinities between 35.4 and 35.5 per mille. They
have also comparatively high temperatures; the isotherm for 10deg.
C. goes down to a depth of about 500 metres in both these parts.

It is obvious that both these comparatively salt and warm volumes
of water belong to the Gulf Stream. The more westerly of them, at
Stations 11 and 12, and in part 13, in the deep sea to the west of
the Porcupine Bank, is probably in motion towards the north-east
along the outside of this bank and then into Rockall Channel --
between Rockall Bank and the bank to the west of the

[Fig. 3 and caption: Fig. 3. -- Temperature and Salinity in the
"Fram's" Southern Section, June, 1910.]

British Isles -- where a corresponding volume of water, with a somewhat
lower salinity, is found again in the section which was taken a few
weeks later by the Frithjof from Ireland to the west-north-west
across the Rockall Bank. This volume of water has a special interest
for us, since, as will be mentioned later, it forms the main part
of that arm of the Gulf Stream which enters the Norwegian Sea, but
which is gradually cooled on its way and mixed with fresher water,
so that its salinity is constantly decreasing. This fresher water
is evidently derived in great measure directly from precipitation,
which is here in excess of the evaporation from the surface of the sea.

The volume of Gulf Stream water that is seen in the eastern part
(east of Station 10) of the southern Fram section, can only flow
north-eastward to a much less extent, as the Porcupine Bank is
connected with the bank to the west of Ireland by a submarine ridge
(with depths up to about 300 metres), which forms a great obstacle
to such a movement.

The two volumes of Gulf Stream water in the Fram's southern section of
1910 are divided by a volume of water, which lies over the Porcupine
Bank, and has a lower salinity and also a somewhat lower average
temperature. On the bank to the south of Ireland (Stations 1 and 2)
the salinity and average temperature are also comparatively low. The
fact that the water on the banks off the coast has lower salinities,
and in part lower temperatures, than the water outside in the deep sea,
has usually been explained by its being mixed with the coast water,
which is diluted with river water from the land. This explanation may
be correct in a great measure; but, of course, it will not apply to
the water over banks that lie out in the sea, far from any land. It
appears, nevertheless, on the Porcupine Bank, for instance, and,
as we shall see later, on the Rockall Bank, that the water on these
ocean banks is -- in any case in early summer -- colder and less salt
than the surrounding water of the sea. It appears from the Frithjof
section across the Rockall Bank, as well as from the two Fram sections,
that this must be due to precipitation combined with the vertical
currents near the surface, which are produced by the cooling of the
surface of the sea in the course of the winter. For, as the surface
water cools, it becomes heavier than the water immediately below,
and must then sink, while it is replaced by water from below. These
vertical currents extend deeper and deeper as the cooling proceeds in
the course of the winter, and bring about an almost equal temperature
and salinity in the upper waters of the sea during the winter, as far
down as this vertical circulation reaches. But as the precipitation
in these regions is constantly decreasing the salinity of the surface
water, this vertical circulation must bring about a diminution of
salinity in the underlying waters, with which the sinking surface
water is mixed into a homogeneous volume of water. The Frithjof
section in particular seems to show that the vertical circulation in
these regions reaches to a depth of 500 or 600 metres at the close
of the winter. If we consider, then, what must happen over a bank in
the ocean, where the depth is less than this, it is obvious that the
vertical circulation will here be prevented by the bottom from reaching
the depth it otherwise would, and there will be a smaller volume of
water to take part in this circulation and to be mixed with the cooled
and diluted surface water. But as the cooling of the surface and the
precipitation are the same there as in the surrounding regions, the
consequence must be that the whole of this volume of water over the
bank will be colder and less salt than the surrounding waters. And as
this bank water, on account of its lower temperature, is heavier than
the water of the surrounding sea, it will have a tendency to spread
itself outwards along the bottom, and to sink down along the slopes
from the sides of the bank. This obviously contributes to increase
the opposition that such banks offer to the advance of ocean currents,
even when they lie fairly deep.

These conditions, which in many respects are of great importance,
are clearly shown in the two Fram sections and the Frithjof section.

The Northern Fram section went from a point to the north-west of
the Rockall Bank (Station 15), across the northern end of this
bank (Station 16), and across the northern part of the wide channel
(Rockall Channel) between it and Scotland. As might be expected, both
temperature and salinity are lower in this section than in the southern
one, since in the course of their slow northward movement the waters
are cooled, especially by the vertical circulation in winter already
mentioned, and are mixed with water containing less salt, especially
precipitated water. While in the southern section the isotherm for
10deg. C. went down to 500 metres, it here lies at a depth of between
50 and 25 metres. In the comparatively short distance between the two
sections, the whole volume of water has been cooled between 1deg. and 2deg.
C. This represents a great quantity of warmth, and it is chiefly given
off to the air, which is thus warmed over a great area. Water contains
more than 3,000 times as much warmth as the same volume of air at the
same temperature. For example, if 1 cubic metre of water is cooled 1deg.,
and the whole quantity of warmth thus taken from the water is given

[Fig. 4. -- Temperature and Salinity in the "Fram's" Northern Section,
July 1910]

to the air, it is sufficient to warm more than 3,000 cubic metres of
air 1deg., when subjected to the pressure of one atmosphere. In other
words, if the surface water of a region of the sea is cooled 1deg. to a
depth of 1 metre, the quantity of warmth thus taken from the sea is
sufficient to warm the air of the same region 1deg. up to a height of much
more than 3,000 metres, since at high altitudes the air is subjected
to less pressure, and consequently a cubic metre there contains
less air than at the sea-level. But it is not a depth of 1 metre of
the Gulf Stream that has been cooled 1deg. between these two sections;
it is a depth of about 500 metres or more, and it has been cooled
between 1deg. and 2deg. C. It will thus be easily understood that this loss
of warmth from the Gulf Stream must have a profound influence on the
temperature of the air over a wide area; we see how it comes about
that warm currents like this are capable of rendering the climate
of countries so much milder, as is the case in Europe; and we see
further how comparatively slight variations in the temperature of the
current from year to year must bring about considerable variations in
the climate; and how we must be in a position to predict these latter
changes when the temperature of the currents becomes the object of
extensive and continuous investigation. It may be hoped that this is
enough to show that far-reaching problems are here in question.