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44
hivningen, at Skrabeposen eller Trawlnettet lagde sig foran
Aabningen og tilstoppede denne. Det første Aar brugtes
mest Skrabe, hvortil tildels det uheldige Vejr var Grunden,
enkelte Gange Ottertrawl og sjælden Bomtrawl. Det andet
Aar kom Bomtrawlen i Brug ved Siden af Skrabe, medens
Ottertrawlen heller ikke sjælden benyttedes. Det tredje Aar
var Bomtrawlen vort Hovedapparat, som da var forsynet
med alle de ovenfor nævnte Forbedringer, og brugtes
overalt, selv paa de største Dybder, hvor Bunden var jevn og
blød. Paa ujevn og haard Bund tik Skraben sin
Anvendelse, hvorimod Ottertrawlen ikke blev benyttet.
Naar Skraben eller Trawlen var kommet ombord,
begyndte Zoologernes og deres Assistenters Arbejde. Før
Apparaterne kom ombord, fyldtes to store Baljer agterud
med Søvand ved Hjelp af Donkeyen (en Hjælpepumpe i
Maskinen). Til Sigtning af det optagne Bundmaterial
brugtes et Sæt runde Sigter, hvert bestaaende af 3 saadanne,
den ene staaende inde i den anden. Den underste Sigt
havde en Diameter af0.m365 (1 Fod 2 Tom.), den mellemste
af 0.ot33 (1 Fod 1 Tom.) og den øverste af 0.’"284(11 Tom.)
Paa alle 3 var Kantens Højde 0.m087 (3l/3’Tom.)
Maskerne var dannede ai Kobbertraade og Aabningen mellem
dem var paa den nederste Sigt 0.mm3 til 0."’m5, paa den
mellemste 1 ."""5 og paa den øverste 2.""" (1 Linie). Sigterne
var forsynede med opstaaende Haandtag paa begge Sider.
Naar Skraben kom ombord, afkappedes først Svaberne
og derefter blev den liret ned paa Dækket. Sømmen i
Sækken blev opsprættet paa begge Sider, og den løsnedes
ligeledes fra Jernrammen paa den Side, som laa op.
Sækkens Overdel toges af, og Indholdet laa afdækket klart til
at tages under Behandling. Fiske, Stene og større
Gjenstande udtoges strax til Opbevaring og nærmere
Bestemmelse. Med en Ose, hvis Bund var af Metalnet, toges af
Assistenterne en Portion af Bundmaterialet op i den øverste
af et Sæt Sigter. Dette sænkedes ned i Vandet i en af
Baljerne, Sigterne bevægedes op og necl, frem og tilbage,
indtil det tine Slam var udslemmet, hvorpaa alle Sigters
Indhold undersøgtes af samtlige Zoologer. Naar
Skrabesækkens hele Indhold paa denne Maade var undersøgt,
skylledes Sækken ren med en Vandstraale ira Donkeyen
og gjordes klar til senere Brug. Svabernes Indhold udtoges
af Zoologerne, et Arbejde, hvortil der i de fleste Tilfælde
maatte benyttes Sax. Af saadanne havdes et større Antal i
Reserve.
Trawlens Indhold af Bundmateriale tømtes paa
Dækket derved, at man løste op Sammensnøringen i Enden af
Bunden.
Den Tid, som en Bundshr åbning tager, er væsentlig
afhængig af Dybden, foruden naturligvis af den Tid, hvori
den egentlige Bundskrabning foregaar. En Statistik herover,
when heaving in the gear, and the bag of the dredge or
trawl was apt at times to twist round and clog the mouth
of the instrument. On the first cruise, in 1876, partly
because of the boisterous weather, we made chief use of the
dredge, working the otter-trawl occasionally; the beam-trawl
was seldom sent down. On the second cruise, both the
beam-trawl and the dredge were in constant use, and we
also worked the otter-trawl with comparative frequence.
On the third and last cruise, the beam-trawl, with the
various modifications before described, had come to be our
principal apparatus; indeed, we used it exclusively in every
locality, even at the greatest depths, on a smooth and soft
bottom. Where the bottom was hard and rugged, we had
recourse to the dredge. Ot the otter-trawl, no use whatever
was made in 1878.
So soon as the dredge or trawl was hauled on deck,
oui’ naturalists and their assistants set to work Shortly
before the apparatus was got in, two large tubs on the
the after-deck were tilled with sea-water by means of
the steam-pump. For sifting the contents ot the bag, we
had a set of 3 sieves, titting freely one within the other
The third or bottom sieve had a diameter of 1 foot 2 inches;
the second of 1 foot 1 inch; and the first of 11 inches.
The depth was the same in each — 3l/3 inches. These
sieves were made of copper wire, the bottom sieve with 0.02
inch meshes, the second with 0.075 inch meshes, and the
first with 01 inch meshes. Each sieve was provided with
a pair of vertical iron handles.
Having hauled the dredge over the railing, the first
thing we did was to cut off the hempen tangles, and
then lower the apparatus on deck. After ripping open
the seam of the bag, the netting, on the side lying up,
was detached from the frame, and the top part of the bag
removed, thus exposing the contents. Fishes, stones, and
all larger bodies were at once laid aside, to be stored for
subsequent examination. With a ladle having the bottom
of brass wire netting, the assistants transferred to the top
sieve part of the sample of the bottom brought up in the
apparatus. The set of sieves were then moved gently up
and down — from side to side — in one of the tubs of water,
till the fine mud or ooze had passed through each, after
which the three naturalists carefully examined the sieves
in succession. When the whole contents of the dredge
or trawl had been sifted and examined, the bag of the
apparatus was thoroughly rinsed, by directing on to it
a jet of water from the steam-pump, and then put by
ready for use. The delicate organisms brought up on the
hempen tangles had mostly to be clipped out with short
scissors, of which there was an ample supply.
For emptying the trawl, we had a contrivance by
means of which the bottom of the bag was made to unlace,
and the contents could thus be deposited on deck without
inverting the apparatus.
The time occupied in a dredging is mainly dependent
on the depth, but of course to a considerable extent also
on the length of the interval devoted to working the in-
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