BJØRN HELLAND-HANSEN AND FRIDTJOF NANSEN. 



M.-N. Kl. 



Fig. 



One 



700 't^ 



Vertical Temperature-Curves of Sect. IV. Readings of Nansen- 

 thermometer are not corrected. 



^soo\^ 



200 



300 tiv^ 



^00 ■ T 



500 



600 



700 



800 ■ 



900 - \ W — 



fOOO 



//00 



/ZOO 



/300 



/400 



The same 

 Richter revers- 

 ing thermome- 

 ter No. 6o was 

 used the whole 

 time. It is not 

 this instrument 



conceivable how 



could suddenly have altered its error 



so considerably as to account for 



the mentioned irrégularités during 



the first period of the expedition (at all 



Stations from No. i to No. 14 in June), 



considering that it has obviously given very 



accurate determinations of the temperature at 



all later stations where we can control them, 



by means of the temperature-readings taken 



in the bottom-water at great depths. 



We must therefore conclude that it is the 

 Nansen-thermometer which has given too low values, 

 and this is conceivable if the drop of mercury found 

 in the upper bulb of the thermometer after its re- 

 turn from the expedition, has been much larger in 

 June, 1910, than it was in July and later (when the 

 error caused by it amounted to 0.13 ^ C, as be- 

 fore mentioned). 



The temperature-curves of Figs. 5 and 6 (Sec- 

 tions IV and VI) do not exhibit any such striking 

 irregularities in the intermediate strata (500 and 

 600 metres) at the boundary between the observa- 

 tions taken with the Nansen-thermometer and those 

 taken with the reversing thermometer. The slight 

 indications of a similar irregularity, which are notice- 

 able, may be accounted for by the error of 0.13" C. 

 which the Nansen-thermometer had later. The 

 readings have naturally also to be corrected for the error caused by the 

 adiabatic cooling during the hauling up of the insulated water-bottle; but it 

 does not amount to much in these observations, 0.03O C. at most [cf. V. W. 

 Ekman, 1905, p. 16]. 



On the homeward voyage in September, Captain Isachsen had the 

 observations at some of the former stations repeated. Fig. 7 shows the 



