13 
■ Tegningen fremstiller Instrumentet klar til Nedfiring; 
Tampen af Lodlinen hexes i øverste Øiebolt (a) og Loddet 
i den nedre (b). I nder Nedffringen løfter Vandtrykket 
Propellerne op, saa at Taggerne i Underkant af Propel- 
bosset (c) kommer klor af Taggerne i Muffen, gjennem hvil- 
ken Ventilstangen (d) gaar, og om de. ikke kommer ganske 
klare, skor Propellens Omdreining mnd Skraaplanerne, saa 
at Muffen og \ entilstangen bliver staaénde stille. Naar 
Instrumentet derimod under Ophalingen bevieges opad. 
driver \ audtrykket Propellerne ned, de dreies rundt den 
anden \ ei og tager Mufierne med sig. Yentilstiengerne. 
der ikke kan dreie sig rundt, men styres af Tværstykkerne 
(e), skrues da, tilligemed de med Kautschuk overtrukne 
Ventiler, mod Ventilsæderne i Enderne af Røret, og naar 
dé ere. næsten lukkede, glipper den sidste Skruegjænge paa 
Ventilstangen ud af Skruegjængerne i Muffen, og Spiral- 
fjædrene (/) klappe da Ventilerne i, medens Propellerne 
og Mufferne gaa løse rundt om den glatte Del af Yentil- 
stængerne, og frembyder saoledes meget liden Modstand 
under Resten af Lndhivningen. Instrumentet lukker sig 
efter omtrent 7 Favnes (13* Meters) Indhaling. . Ringen 
om Midten og Skjærmerne rundt Propellerne beskytte 
Instrumentet, saaledes at det ilden Skade kan ligge paa 
Bunden. 
For at' konstatere, om der var Overskud a f Luft i 
de nedre Vandlag, blev der over Svikbullet paaskruet et 
gjennomboret Laag (f/), der ved Hjælp af et Stykke Gummi- 
slange forenédes til et i den ene ' Ende lukket Glasrør. 
Naar Våndet under Npdfiringen strønunede ind i Vand- 
røret, løb det ogsaa ned i Glasrøret, af hvilket Luften saa- 
ledes blev udjnget. Naar Instrumentet kom ombord, ende- 
•vendtes det. saa at . Kranen kom ned og Glasrøret op. Man 
bevægede nu Vandhenteren lidt frem og tilbage med den 
øvre Ende. og hvis der havde været Overskud af Luft. 
maatte denne have arbeidet sig op og vist sig i Toppen af 
Glasrøret. men dette viste sig stadig fuldt lige til Tops, og 
blev derfor i* den sidste Tid ikke paasnt." 
Instrumentet kan tømmes gjennem Tappekranen (h) 
og leverer en Vandprøve paa circa 5 Litre. 
Udførelsen af de chemisko Arbeider ombord paa den 
norske Nordhavsexpedition overtoges altsaa først i Følge 
den oprindelige Plan af Hr. Svendsen, som gjorde Togtet 
i 1870 med. men blev senere, da denne af Helbredshensyn 
bad sig fritaget, overdraget Forfatteren, der saaledes har 
udført de paa de to sidste Togter gjorte Observationer del- 
vis med Assistance af Hr. L. Schmelck, sonr sidste Sommer 
medfulgte Expeditionen. og som for Tiden er beskjæftiget 
med Bearbeidelsen af en anden Del af det paa Expeditionens 
Togter til chemisk Undersøgelse indsamlede Materiale. 
The figure shows the instrument ready for sinking. 
The end of the sounding-line is made fast to the upper eve- 
holt (<0. and the lead to the lower (/>). On the down- 
ward passage, the pressure of the water lifts up the pro- 
pellers. enabling the cogs in the under surface of the base 
of the latter (e) 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 revolves with the inclined planes, 
the bush and the rod of the valve remaining stationary 
as before. On the other hand, when the instrument, 
on being hauled in. is given an upward motion, the pres- 
sure of the water forces down the propellers, which then 
revolve in the opposite direction, carrying along with them 
the bushes. The. rods of the valves, which cannot revolve, 
being kept in position bv transverse pieces (e), are, tqgether 
with the valves covered with caoutschouc, screwed against 
the ends of the tube. Now. when the latter are almost 
closed, tin* last twist of the screw on the rod of the 
valve slips out of the corresponding twist of the screw 
on the bush, and the spiral springs (/) instantly press 
down the valves, the propellers and the bushes revolving 
independently round the smooth portion of the rods, thus 
presenting but little resistance to the water during the 
refnainder of the upward passage. The instrument closes 
on being hauled' in about 7 fathoms (13 metres). The 
ring round the middle, and the shields protecting the 
propellers, prevent the instrument from sustaining injury 
on its striking the bottom. 
With a view to ascertain whether tin* proportion of 
air were, really greater in the lower strata, a perforated 
cover ((f) was screwed over the spigot-hole, and • con- 
nected by means of a piece of caoutschouc hose with a glass 
tube, open at one end. Now. when the water on the 
.downward passage flowed into the spiral tube, it also de> 
sconded into the glass tube, expelling the air. * So soon 
as the instrument came on board, it was inverted, the 
. stop-cock therefore pointing down, and the glass tube up. 
The upper end of the apparatus being now moved a little 
backwards and forwards, the surplus of air. if any had 
been present, must obviously have forced its way up- 
wards. and have appeared, in the form of bubbles, at 
the top of the tube, which, however, was invariably found 
to b$ quite full, and therefore not attached to the appa- 
ratus when the fact would no longer admit of doubt.” 
' The stopcock (h) serves to empty the instrument, 
which will hold about 5 litres of water. 
The chemical work to be done on board was. as 
stated above, originally undertaken by Mi*. S. Svendsen, 
who went out on the first cruise, in 1870; but. his health 
failing, Mr. Svendsen was succeeded by the author, who 
had therefore to take the observations instituted in 1877 
and 1878. partly with the assistance of Mr. L. Schmelck. 
that gentleman having accompanied the Expedition on the 
last cruise. (Mr. Schmelck is now engaged in working uj> 
other materials collected on the Expedition for chemical 
investigation). 
