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15
Thermometre. — De Dybvandsthermometre, der
benyttedes paa vor Expedition, vare Casella-Millers.
Buchanans (Kviksølvpiezometer) og Negretti og Zambras, den
ældre og den nyere Model. Desuden gjordes Forsøg med
Vantl-Piezometre til Kontrolbestemmelser for de maalte
Dybder. Alle disse Instrumenter ville blive beskrevne af
Professor Mohn i hans Afhandling om
Dybvands-Temperaturerne.
Vandlienter. — Paa vor Expedition anvendtes
hovedsagelig den af mig dertil konstruerede, i Fig. 11 i 1/8 af den
sande Størrelse fremstillede Vandlienter. Instrumentet, der
blev prøvet i Christiania før det blev antaget, blev brugt
under den hele Expedition, saavel paa de større som paa
mindre Dyb. ’ Da Kemikeren havde stillet Fordring paa
5 Liter Vand, blev Apparatet meget stort, hvilket vistnok
ikke generede Indhalingen i mærkelig Grad. men det gjorde
det noget tungvindt at haandtere paa Dæk.
Vandhenteren er i Figuren fremstillet færdig til
Ud-liring. Tampen af Lodliiien hexedes i øverste («) og
Loddet i nederste Øjebolt (6). Under Udfiringen strømmer
Vandet frit gjennem det, for Pladsens Skyld, spiralformig
bøjede Rør, der var af Kobber og indvendig fortinnet.
Samtidig løftes Propellerne op. saa at Taggerne i
Underkant af Propelbosset c kommer klar af Taggerne i Muffen
om Ventilstangen, og om de ikke skulde komme ganské
klare, sker Propellens Omdrejning med Skraaplanerne, saaat
Muffen og den gjennem samme gaaende Ventilstang d bliver
staaende stille. Naar derimod Instrumentet under
Indhiv-ning bevæges opad, trykker Vandtrykket Propellerne ned,
de drives rundt den anden Vej og tager Muffen med sig.
Ventilstængerne, der styres af Tverstykkerne e og
Ventilerne, der ere overtrukne med Kautschuk, skrues da mod
Ventilsæderne i Enden af Røret, og naar de er næsten
lukkede, glipper den sidste Skruegjænge i Ventilstangen ud
af Skruegjængerne i Muffen og Spiralfjædrene (/) klappe
da Ventilen i, og holder dem lukkede under Resten af
Indhivningen. medens Propellerne og Mufferne gaa løse
rundt den glatte Del af Ventilstangen og saaledes frembyde
meget liden Modstand. Instrumentet lukkede sig efterat
være indhalt 6 å 7 Favne. Skjærmene om Propellerne
beskytter disse, saa at Instrumentet uden Skade kan ligge
paa Bunden.
Da man ønskede at konstatere, om der var Overskud
af Luft i de dybere Vandlag, blev der over Svikhullet (g)
paa Røret paaskruet et gjennemboret Laag, og dette blev
forenet med et i den ene Ende lukket Glasrør ved Hjælp
af et Stykke Kautschukslange. Naar Vandet under
Nedfiringen strømmede ind i Vandrøret, løb det ogsaa ned i
the year after (1878), strengthened, however, on the latter
part of the cruise with a few spare straps.
Thermometers. — Of deep-sea thermometers, the
Expedition was provided with the Miller-Casella. Buchanan’s
(mercury-piezometer), and Negretti & Zambra’s (on the
original and the improved construction.) Experiments
were also made with water-piezometers, to control
determinations of depth. These instruments will all be described
by Professor Mohn. in his Memoir on the deep-sea
temperatures.
The Water-Bottle. — For collecting water both from
the bottom and intermediate depths, we made chief use, on
each of the three cruises, of an instrument devised by
myself, and tested in Christiania previous to the departure
of the Expedition. Fig. 11 represents this water-bottle,
one-eighth of the actual size. The apparatus having, as
stipulated by Mr. Svendsen, chemist to the Expedition, to
bring up 5 ’litres of waters, it was of course rather
bulky; but this, though it made the instrument somewhat
cumbersome to handle on deck, did not materially impede
the heaving in.
In the figure, the water-bottle is shown ready to let
go. The end of the sounding-line is shackled to the
upper eyebolt (a), and the lead to the lower (b). On the
downward journey, the water passes freely through the
tube, which is of copper, tinned on the inside, and which,
to save space, had been given a spiral form. Now, the
pressure of the water will lift up the propellers, enabling
the cogs in the under surface of the boss (c) to get clear
of the cogs in the bush, through which passes the rod of
the valve (d); and if not quite clear, the propeller will
revolve with the inclined planes, the bush and the
valve-rod remaining stationary as before. On the other hand,
when the instrument, on being hauled in. is given an
upward motion, the pressure of the water will force down
the propellers, and they will then revolve in the opposite
direction, carrying along with them the bushes. The
valve-rods. which cannot revolve, being kept in position by the
cross-pieces (e), will then, together with the valves, covered
with india-rubber, be screwed against the valve-seats. When
the valves are well-nigh closed, the last twist of the screw
on the rod of the valve will slip out of the corresponding
twist of the screw on the bush, and the spiral springs (/)
instantly press down the valves and prevent the enclosed
sample of water from escaping, the propellers and the
bushes being left to revolve independently round the flush
portion of the rods, thus affording very little resistance on
the passage to the surface. The instrument closes on being
hauled in 6 or 7 fathoms. The shields round the
propellers serve to protect them from damage when the
instrument is lying on the bottom.
With a view to ascertain whether the proportion of
air were really greater in the deeper strata of the ocean,
a perforated cover was screwed over the spigot-hole (g),
and connected, by means of a short piece of india-rubber
hose, with a glass tube, sealed at one end. Now. when the
water on the downward passage of the instrument entered
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