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Temperatur-Rækker.
Serial Temperatures.
Til Undersøgelse af Temperaturen i forskjellige
Dybder paa samme Station toges Temperatur-Rækker. Disse
udførtes i Regelen saaledes: Rørloddet hexedes i Lodlinen,
og lige ovenfor Loddet fastgjordes et Dybvandsthermometer,
ganske som ved Lodning. Indhivningsmaskinen udliredes
100 Favne, og Thermometer No. 2 gjordes fast i Lodlinen
fra Loddebroen. Atter udfiredes det andet 100 Favne og
Thermometer No. 3 paasattes Linen. Paa denne Maade
anbragtes 5 a 6 Thermometre paa Linen med 100 Favnes
Afstand og sænkedes ved Udfiring fra Indhivningsmaskinen
til de Dybder, i hvilke man vilde maale Temperaturen.
Naar alle Thermometre havde faaet Tid til at accommodere
sig, haledes Linen ind med Maskinen. Der stoppedes saa
lang Tid, som var nødvendig for at løse Thermometret
fra Linen, efterhvert som de kom op. Der lagdes megen
Vind paa jevne Bevægelser under disse Operationer, for
ikke at udsætte Indexthermometrene for pludselige Ryk
eller Stød. 1 høj Søgang maatte der benyttes megen
Forsigtighed ved Thermometrets Aftagning af Linen.
Fartøjet laa i Regelen, som ved Lodning, med Stevnen mod
Søen, men man kunde ikke altid holde Lodlinen saaledes,
at den kunde naaes med Haanden fra Loddebroen. Linen
maatte da bringes ind til Broen ved Hjælp af en
Baads-hage, der maatte gribe Linen under Thermometret for
ikke at komme til at berøre dette.
Temperaturrækkerne udførtes kun meget faa Gange
ved at lade Linen labe ud fra Rullen, da dens Standsning
let medførte Ryk. som ialfald Indexthermometre ikke maa
udsættes for.
Temperaturrækker paa Dybder mindre end 50 Favne
udførtes ofte med Haandlod og Haandline, der havde
Marker for hver 5 eller 10 Favne.
Temperaturrækkerne toges i Almindelighed strax
efter et Lodskud. Flere Gange blev der dog efter
Lodskuddet arbejdet med Skrabe eller Trawl, naar saadant faldt
belejligere, og Temperaturrækken toges da efter at disse
Arbejder var færdige. Paa denne Maade er det gaaet til.
at Temperaturrækkens paa værende Plads undertiden er lidt
forskjellig fra Lodskuddets.
Varigheden af en Temperaturrække er naturligvis
forskjellig efter Antallet af Dybder, hvori Temperaturen
tages og efter Dybdernes Størrelse. En Statistik, taget
af Skibsjournalen, viser, at der til Lodskud og
Temperatur-række medgik omtrentlig:
Paa et Dyb af 100 Favne 30 til 50 Minutter.
_ . . _ 500 — 1 Time 40
- - - - 1000 — 2 Timer 30
- - - - 1500 — 3 —
- - - -2000 — 3 til 3 Timer 30
Minutter.
For determining the temperature of the sea in
different depths at the same observing-station, we took series
of temperatures. Our mode of operation was generally as
follows: — After shackling the tube-lead to the sounding-line,
we attached, just above the weight, a deep-sea
thermometer, precisely as for ordinary soundings. Then, 100 fathoms
of line were veered out with the*donkey-engine, and
Thermometer No. 2 made fast, from the sounding-bridge, at the
first hundred-fathom slip, after which we veered another
100 fathoms, and attached Thermometer No. 3 to the line
at the second slip. In this manner, as many as 5 or 6
thermometers were made fast to the sounding-line at
intervals -of 100 fathoms, and sent down to register the
temperature in the desired depths. So soon as the
thermometers had had time to take the temperature of the
surrounding water, we started the donkey-engine and began hauling
in the lead, stopping, as each of the thermometers came
up over the rail of the bridge, to detach it from the
line. Very great importance was attached to uniformity of
mo.tion pending these operations, so as not to expose the
index-thermometers to any sudden jerk or shock. In a
heavy sea, we had to be specially careful when taking the
thermometers off the line. The ship generally lay head to
sea, as she did during the descent of the lead:
nevertheless. we sometimes found it impossible to keep the line
within reach from the sounding-bridge, in which case it
was got in with a boat-hook, care being taken to hook the
line below the thermometer, and thus avoid coming in
contact with the latter.
Only a few serial temperatures were taken by letting
the line run out of itself, the necessary stoppages in that
case easily occasioning jerks, to which the
index-thermo-meters. at least, must not be exposed.
At depths of less than 50 fathoms, serial
temperas-tures were frequently taken with the hand-lead, the line
being graduated into fives or tens" of fathoms.
As a rule, we took our serial temperatures
immediately after sounding. On several occasions however, the
dredge or trawl was. worked in preference, the serial
temperatures being in that case deferred till we had terminated
those operations. This accounts for the position in which
certain of the serial temperatures were taken differing
slightly from that of the soundings.
The time required to take a serial temperature will
obviously depend alike on the depth and the number of
temperatures. Data obtained from the ship’s log-book show
the time occupied in taking a sounding and a serial
temperature to have averaged as follows: —
For a Depth of 100 Fathoms from 30 to 50 minutes.
- 500 — 1 hour 40 minutes.
. . _ -1000 — 2 hours 30
- - - 1500 — 3 —
— - 2000 — from 3 hours to 3 hours
30 minutes.
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