13 



■ Tegningen fremstiller Instrumentet klar til Nedfiring; 

 Tampen af Lodlinen hexes i øverste Øiebolt (a) og Loddet 

 i den nedre (6). Under Nedfiringen løfter handtrykket 

 Propellerne op, saa a1 Taggerne i Underkant af Propel- 

 bossel £c) kommer klar af Taggerne i Muffen, gjennem hvil- 

 ken Ventilstangen (d) gaar, og om «le ikke kommer ganske 

 klare, sker Propellens Omdreining med Skraaplanerne, saa 

 ai Muffen og Ventilstangen bliver staaende stille. Naar 



Instrumentet deri il muler Ophalingen bevæges opad, 



driver Vandtrykket Propellerne ned. de dreies rundt den 

 anden Vei Og tager Mutterne med sig. Ventilstængerne, 

 der ikke kan dreie sig rundt, men styres af Tværstykkerne 

 (i i. sknies da, tillikemed de med Kautschuk overtrukne 

 Ventiler, mnd Ventilsæderne i Enderne af Horet, og naar 

 de 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 lose rundt om den glatte Del af Ventil- 

 stængerne. og frembyder saaledes meget liden Modstand 

 under Resten af Indhivningen. Instrumentet lukker sig 

 etter omtrent 7 Favnes (13 Meters) Indhaling. Ringen 

 om Midten og Skjærmerne rundt Propellerne beskytte 

 Instrumentet, saaledes at det uden Skade kan ligge paa 

 Bunden. 



For at konstatere, om der var Overskud af Luft i 

 de nedre Vånding, blev der over Svikhullet paaskruet et 

 gjennemboret Lang (//). der ved Hjælp at' et Stykke Gummi- 

 slange forenedes til et i den ene Ende lukket Glasrør. 

 Naar Våndet under Nedfiringen strømmede ind i Vaud- 

 røret, løb det ogsaa ned i Grlasrøret, af hvilket Luften saa- 

 ledes blev udjaget. Naar Instrumentet kom ombord, ende- 

 vendtes det. saa at Kranen kom ned og Glasrøret op. Man 

 bevægede nu Vandljenteren lidt frem og tilbage med den 

 ovre Ende, og hvis der havde været Overskud af Luft. 

 maatte denne have arbeidet sig op og vist sig i Toppen af 

 Grlasrøret, men dette viste sig stadig fuldt Jige til Tops, og 

 blev derfor i den sidste Tid ikke paasat." 



Instrumentet kan tommes gjennem Tappekranen (h) 

 og leverer en Vandprøve paa circa 5 Litre. 



Udførelsen af de chemiske Arbeider ombord paa den 

 norske Xordbavsexjiedition overtoges altsaa forst i Folge 

 den oprindelige Plan af Hr. Svendsen, som gjorde Togtet 

 i 1876 med. men blev senere, da denne af Eelbredsbensyn 

 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, som sidste Sommer 

 medfulgte Expeditionen. og som for Tiden er beskjæftiget 

 med Bearbeidelsen af en anden De] af det paa Fxpeditionens 

 Togter til chemisk Undersøgelse indsamlede Materiale. 



Tbe figure shows tbe instrument readj for sinking. 

 The end of the sounding-line is made fast fco fche upper eye- 

 bolt (a), and the lead fco the lower (&). On the down- 

 ward passage, the préssure*of the water lifts up the pro- 

 pellers, enabling the cogs in the under surface of the base 

 of the latter (c) to gel cléar of the cogs in the bush, 

 through which passes the rod of the valve (d); and if not 

 quite clear, the propeller revblves with the inclined planes, 

 the bush and the rod of the valve remaining stationarj 

 as before. < >n the other band. when the instrument, 

 on being bauled in. is given an upward motion, the pres- 

 sure of the water forees down the propellers, which then 

 revolve in the opposite direction, carrying along with them 

 the busbes. The rods of the valves. which cannot revolve. 

 being kept in position by transverse pieces (e), are. together 

 with the valves covered with caoutschouc. screwed against 

 the ends of the tube. Now, when the latter are almost 

 closed. the last twist of the screw on the rod ef the 

 valve slips out of the corresponding twist of the screw 

 on the bush. and the spiral springs (f) 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 

 remainder of the upward passage. The instrument cio es 

 on being bauled 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 the proportion "f 

 air were really greater in the lower strata, a perforated 

 cover (cf) was screwed over the spigot-hole, and con- 

 uected by means of a piece of caoutschouc hose -with a glass 

 tube. ojien at one end. Now, when the water on the 

 downward passage flowed into the spiral tube. it also de- 

 scended into the glass tube. expelling the air. So soon 

 as the instrument came on board, it was inverted, the 

 stop-cock therefore pointing down. aud the glass tube up. 

 The upper end of the apparatus being now moved a little 

 backwards and forwards, the surplus of air. if any bad 

 been present, must obviously have forced its way up- 

 wards. and have appoared. in the tonn of bubbles. at 

 the top of tbe tube. which. however. was invariably found 

 to be 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 Mr. S. Svendsen, 

 who went out on the first cruise, in 187ti: but, his health 

 la din»-. Mr. Svendsen was succeeded by the author, who 

 bad 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 up 

 other materials collected on the Expedition for chemical 

 investigation). 



