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II.
Havets Temperatur.
il.
Temperature of the Sea.
I. De benyttede Instrumenter.
Angaaende Iagttagelsen af Havoverfladens Temperatur
henvises til min Afhandling „Meteorologi" Side 46.
Til Expeditionen første Rejse i 1876 var anskaffet
10 Miller-Casella’s Dybvandsthennometre af den
almindelige Construction og Storrelse (Indfatningsrammen 23 cm.).
Disse Instrumenter ere nu saa ofte beskrevne1, at det ikke
her er nødvendigt at beskrive dem nøjere. De vare
inddelte i Celsius-Grader og prøvede ved et Tryk af 2.5
Tons pr. Kvadrattomme. De fra Fabrikanten opgivne
Correctioner for Tryk kom, som senere skal omtales, ikke
til Anvendelse ved Observationernes endelige Beregning.
De 9 af disse Instrumenter, der jevnlig anvendtes paa
alle Expeditionen tre Togter, ere i det følgende betegnede
ved Romertallene I til IX.
I 1876 og 1877 anvendtes nogle faa Gange et
Dyb-vandsthermometer af Negretti ct Zambra.2 Det er U-formet
og havde en Vendemekanisme, der ved Ophaling virkede
gjennem en Skruepropeller. Da den oprindelige
Vendemekanisme virkede saa hurtigt, at man var udsat for, at
Thermometret under Søgang kunde vende sig, og derved
registrere Temperaturen, førend det havde accommoderet
sig, blev Mekanismen af Capt. Wille til Rejsen i 1877
forandret til en langtsomt virkende. Ved Temperaturrækker
haledes da Lodlinen, efterat Thermometret havde
accommoderet sig i Dybet, ind nogle Favne og firedes atter
ud, hvilket gjentoges saamange Gange, at man var sikker
paa, at Thermometret var vendt. Derpaa begyndte den
egentlige Indhaling. En saadan Operation tog megen Tid,
hvorfor Instrumentet sjelden anvendtes. Instrumentet
betegnes i det Følgende ved N Z.
Se f. Ex: W v ville Thomson. The Depths of the See. S. 291.
Beskrevet i -Nature," Vol IX. S. 3s7.
Den norske Nord lin vsexpodition. H. Mohn: Nordhavets Dybder, Te
I. Instruments.
Respecting the observations taken of the
temperature of the sea-surface, I refer to my Memoir —
"Meteorology," p. 46.
For the first cruise of the Expedition, in 1876, had been
provided 10 deep-sea Miller-Ca sella thermometers, of the
usual construction and size (frame 23 cm.). These
instruments have been so often described1 as to render further
description here superfluous. They were divided in
degrees centigrade, and had been tested by a pressure of 2.5
tons per square inch. The corrections given by the
in-strument-maker were not, as will be subsequently explained,
made use of when finally reducing the observations. Of
these instruments, the 9 in constant use on each of the
3 cruises of the Expedition will be indicated by the Roman
letters I to IX.
In 1876 and 1877, a deep-sea thermometer by
Negretti and Zambra was used on a few occasions.- This
instrument is U-shaped and furnished with a
mechanism for turning over in the water, which, on hauling
it in, acts by means of a small propeller. The
original mechanism operating with such rapidity that in a
heavy sea the thermometer was liable to turn over and
register the temperature before the instrument could
accomodate — Capt. Wille gave it, for the cruise in
1877, a slower-acting mechanism. AVhen measuring serial
temperatures, the sounding - line was hauled in a few
fathoms, as soon as the thermometer had been given
time to accomodate in the deep, and then veered out
again, the operation being repeated sufficiently often to
ensure the thermometer having turned over. Then
commenced the final hauling-in. An operation of this kind
naturally took up a great deal of time, and hence the
instrument was seldom made use of. This thermometer
will be indicated by the letters N Z.
1 See. for example, Wyville Thomson. The Depths of the Sea. p. -J<>].
2 Described in "Nature." Vol. IX. p. :>S7.
eratur og Strmnninger. 2
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