136 



FRIDTJOF NANSEN. 



carefully, and it gives the temperature with an accuracy of 

 0-002° G. 



Temperature-readings obtained from any depth of the sea 

 with a water-bottle with perfect insulation, have to be corrected 

 for the instrumental error of the thermometer, and if the tempe- 

 rature in situ be desired, also with a correction for the pressure 

 of the water. 1 



This correction changes with the temperature of the water- 

 sample and the depth, and may be found from the following 

 table for depths between 200 and 3000 m. 



Temperature 

 of Water- 



200 



400 



600 



800 



1000 



1500 



2000 



2500 



3000 



Sample 



m. 



m. 



m. 



m. 



m. 



m. 



m. 



m. 



m. 





°c. 



°c. 



°c. 



°C. 



°C. 



°C. 



°C. 



°C. 



°C. 



— 2°C. 



+0-00 



+0^01 



+0-01 



+0-01 



+0-02 



+0-03 



+004 



+0^04 



+0-05 



-1 - 



•01 



•01 



•02 



•02 



•03 



•04 



■05 



•07 



•08 









•01 



•02 



•02 



•03 



•04 



•06 



•08 



•09 



•11 



1 





•01 



■02 



•03 



•04 



•05 



•07 



■09 







2 





•01 



•02 



•03 



•04 



•06 











3 





•01 



•03 



•04 



•05 



•06 











4 





•01 



•03 



•04 



•06 



•07 











5 





•02 



•03 



•05 



•06 



•08 











6 





•02 



•04 



•05 



•07 













All corrections have to be added to the temperature rea- 

 dings. 



The deep-sea temperatures were also determined with the 

 Negretti and Zambra Reversing Thermometers. The difficulty 

 v^ith these thermometers is that the mercury seldom breaks off 

 exactly at the same place of the contraction, and thus a high 

 degree of accuracy cannot as a rule be attained with them. 

 Besides this, the glass of the thermometers is not generally of 



1 Cf. Nansen, 'Oceanography of the North Polar Basin', The Norwegian 

 North Polar Expedition 1893—1896. Scientific Results, Vol. Ill, No. IX, 

 pp. 4 et seq. 



