Full resolution (JPEG) - On this page / på denna sida - Sidor ...
<< prev. page << föreg. sida << >> nästa sida >> next page >>
Below is the raw OCR text
from the above scanned image.
Do you see an error? Proofread the page now!
Här nedan syns maskintolkade texten från faksimilbilden ovan.
Ser du något fel? Korrekturläs sidan nu!
This page has never been proofread. / Denna sida har aldrig korrekturlästs.
54
Der findes imidlertid blandt vore Stationer nogle,
hvor Usikkerheden af den paaværende Plads gaar op til 5
å G Minuter, nemlig udenfor den nordvestlige Del af
Spidsbergen. nordenfor 78° Bredde. Efterat den paaværende
Plads var bestemt ved Solobservationer saavel Formiddag
som Eftermiddag, viste det sig, da vi fik Land i Sigte, at
Resultatet af Pejlinger af Norclpynten af Pr. Charles
Foreland gav en 5’ til 6’ sydligere Plads end
Solobservationerne. Men Aarsagen viste sig ogsaa i en stærk
Hildring, der krævede en anden Værdi for
Kimmingdalm-gen end den normale, som var benyttet. Under saadanne
Forhold er paaværende Plads umulig at bestemme med
vanlig Nøjagtighed efter Solobservationer, selv om man laa
for Anker og observerede Højder i alle Azimuther, thi
Horizontalrefraktionen vil variere med Retningen og med
Dagstiden paa en ganske uperiodisk Maade, der er umulig
at bringe i Regning. Et lignende Exempel paa Virkningen
af Hildring havde vi om Morgenen den 10de August 1877
udenfor Lofoten. Maaling af Horizontalvinkler mellem
kjendte Punkter gav Fartøjet en paaværende Plads, der
laa i en betydelig Afstand fra den Stedlinie, som en over
den østlige, falske Horizont maalt Solhøjde gav.
Til Slutning skal jeg nævne, at Expeditionen var
udrustet med Apparater til at maale Strøm i Overfladen og
paa Dybet. Disse kom ikke til Anvendelse, først fordi
Vejret det første Aar var saa særdeles ugunstigt, og senere
fordi de andre Arbejder, som skulde udføres, krævede al
vor Tid og ikke turde forsinkes af Operationer, oiu hvilke
det altid maatte være tvivlsomt, hvorvidt noget brugbart
Resultat kunde erholdes. Bestemmelser af Strømmen i Overfladen
efter den almindelige nautiske Methode lod sig ikke.
undtagen i yderst faa Tilfælde, udføre paa vor Expedition, da
Sejladsen under Skrabning, som nævnt, umuliggjorde et
skarpt Bestikliold.
Meanwhile, for some of our observing-stations. the
possible error of the ship’s position amounts to from 5 to
6 miles, viz. those oft" the north-western extremity of
Spitz-bergen, in latitude from 78° to 80° N. After determining
the ship’s position by observations of the sun’s altitude,
taken before as well as after noon, we found, on sighting
land, the bearing of the northern promontory of Prince
Charles’ Foreland to give a point from 5 to (3 miles farther
south than that determined by the solar altitudes. This,
however, was obviously the result of mirage; and hence
our constant value for the dip of the horizon would not
serve. Under such circumstances it is impossible, were the
ship at anchor even and the altitudes observed in all
azimuths, to determine hei- position with the usual accuracy
by observations of the sun. since the horizontal refraction
according to the direction afid the time of day will not vary
periodically, and its true value cannot be taken into account.
A similar instance of the effects of mirage occurred on the
morning of the 10th of August 1877. oil’ Lofoten. By
measuring horizontal angles between known objects, we
found the ship’s position to be a considerable distance from
the line of equal altitudes marked out from observations
of the sun above the eastern delusory horizon.
Finally, I must not omit to mention that the
Expedition was provided with instruments for determining both
surface and deep-sea currents. These apparatus, however,
were not made use of. — at first owing to the very
unfavourable weather we encountered on the opening cruise, and
afterwards to avoid impeding the chief exploratory work by
operations from which it was anything but certain that
practical results would be obtained. Nor had we, save in
a very few cases, opportunity of determining the
surface-current in the usual nautical way, the effect of dredging and
trawling, as stated above, inevitably putting us out of our
reckoning.
Translated into English by John Hazeland.
<< prev. page << föreg. sida << >> nästa sida >> next page >>
