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45
udregnet af Skibsjournalens Opgaver over Klokkeslettet, da
Skrabe (Trawl) blev sat ud, da Lodderne blev slupne, da
man begyndte Bundskrabuingen, da den endte, og
Indhiv-ningen begyndte, og da Skraben (Trawlen) kom op igjen,
viser, at en Skrabning paa 100 Favnes Dyb gjennemsnitlig
tog l1/2 Time, paa 500 Favnes Dyb 4’/4 Time. paa 1000
Favnes Dyb 71/3 Time. paa 1500 Favnes Dyb 10’ L. Time.
Eller, udtrykt vecl en Tilnærmelsesformel, kan man sige, at
Tiden for en Bundskrabning —
1.5+ (Dybden — 100-Fv.) 0.654 Timer.
Denne Formel giver for en Dybde af 2000 Favne
en Tid af 14 Timer. Forresten kunde Tiden for en
Bundskrabning paa en vis Dybde være temmelig
forskjellig, eftersom Manøvren gik mere eller mindre heldig.
A ar Trawlen meget tung f. Ex., maatte der hives
langsommere ind. 1 1878. da Trawlen mest var i Brug. varede
gjerne selve Skrabningen længere end tidligere (2 Timer
mod ll/2 Time), og Trawlen var ofte meget tung. Det
viser sig af vor Statistik ogsaa, at Varigheden af den hele
Operation gjennemsnitlig i 1878 var større end i 1877.
Overfladenet. Foruden de ovenfor beskrevne
Fangstredskaber brugtes ogsaa meget hyppigt af Prof. Sars et
Overfladenet, som bestod af en omtrent 1 Meter (3 Fod)
lang Pose af fin Kammerdug, spids i den ene Ende. og
aaben i den anden, der var fæstet til en Ring af
Messing-traad. Til denne blev fastgjort i Hanefod en smækker
Line. Naar der ved Ankomsten til en Arbejdsstation blev
kommanderet "Sagte", udkastedes Nettet, og det slæbte
efter Skibet under den aftagende Fart. Undertiden blev
det ogsaa blot kastet ud fra Fartøjet under Stilleliggen og
strax indhalet.
strument when down. Reference to the ship’s logbook, in
which were recorded the details of every operation,
comprising the moment at which the dredge (or trawl) was
put over, that at which the sinkers were let go, the actual
dredging was commenced and terminated, when the heaving
in began, and when the apparatus was hauled on deck, —
shows the average time to have been as follows: — At a
depth of 100 fathoms. 1 hour 30 min.; at a depth of 500
fathoms. 4 hours 30 min.; at a depth of 1000 fathoms, 7
hours 20 min.; and at a depth of 1500 fathoms. 10 hours
30 min. Or. expressed by an approximate formula, the
time required for a dredging
1.5 -f (the depth —100 fathoms) 0.654 hours.
For 2000 fathoms, this formula will give 14 hours.
Meanwhile, the time a dredging would occupy at any
given depth, was found to vary not a little according
to the greater or less success attending the
operation. And moreover, if the trawl had got an
exceptionally heavy freight, the rate of heaving in had to be reduced.
In 1878, when chief use was made of the beam-trawl, we
as a rule kept the apparatus longer at the bottom than
on the two preceding cruises, and it often came up very
heavy It appears, too. from the entries in the log-book,
that the average duration of a cast of the trawl in 1878 was
greater than in 1877.
The Toil-Net. — Among the apparatus for
prosecuting zoological work was a tow- or surface-net, of which
Professor Sars made frequent use. It consisted of a
conical muslin bag, 3 feet deep, attached to a stout brass ring,
which, by means of a crow-foot, was made fast to a line
of suitable thickness. Shortly before our arrival at an
obser v i ng-station, after the ship’s way had been deadened,
Professor Sars cast out the tow-net. which was pulled
along after the vessel till she stopped. Sometimes, he
merely threw it over and hauled it in when there was no
way on the ship.
Navigering.
Til Expeditionen var anskaffet et Admiralitets -Kompas
fra England. Dets Plads var. som tidligere anført, strax
forenfor Bestiklugaret paa Hytten (Fig. 2 c). Dets
Deviation bestemtes ved Svingning af Skibet, i 1876 i Husø, i
1877 i Husø, ved Røst og i Vestfjorden, i 1878 i Bergen,
paa Kysten af Øst-Finmarken nær Vardø, udenfor Sørøen
ved Hammerfest, paa Ishavet vestenfor Beeren Ei land,
under Beeren Eiland, under Spidsbergens Sydkap, under
Grønlandsisen paa 76^2 Grads Bredde. Observationerne
blev beregnede efter Archibald Smiths Methode strax efter,
at de var tagne, og Resultaterne anvendte til Bestemmelse
af Kursen. De benyttede Værdier af Misvisningen toges
af de norske, britiske og danske Søkarter, naar
Misvisningen ikke var bestemt ved vore egne Observationer.
Navigating the Ship.
An Admiralty-compass had been procured from
England for the Expedition. Its place, as previously stated,
was just forward of the chart-room on the roundhouse.
The deviation of the instrument we determined by
swinging the ship, — in 1876 at Husø; in 1877 at Husø, at Røst,
and in the Vestfjord; in 1878 at Bergen, off the coast of
East Finmark (near Vardø), off Sørøen (near Hammerfest),
in the Arctic Ocean (west of Beeren Eiland), off South
Cape. Spitzbergen. and off the Greenland ice-barrier, in
lat. 76° 30’ N. Immediately on being taken, the
observations were computed by Archibald smith’s method, and
the results employed for shaping the ship’s course. The
variation was taken lirom the Norwegian, British, or Danish
charts, when not previously determined by our own
observations.
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