612 



H. MOHN. METEOROLOGY. 



[nORVV. POL. EXP. 



The winter-hut lay about 7 or 8 metres above the level of the sea. The 

 observations made from August Se"*, 1895, to May IQ*"*, 1896, at or in the 

 hut, have been reduced to sea-level by adding 0'7 mm. 



The uncertainty attaching to the corrections of the aneroids has induced 

 me to give in an extra column the direct readings of these instruments. 



For the observation of the temperature of the air the expedition had 5 

 thermometers. Three of these were mercury sling- theimometers, No. 14, No. 

 18 and No. 20, and two minimum registering thermometers, Toluol B and 

 Metaxylol C. The zero of all the 5 thermometers had been determined in 

 April 1893, at the Meteorological Institute in Christiania. On board the Fram 

 the zero of No. 20 was verified in February and in April, 1894, and the two 

 index-thermometers were compared at low temperatures, — 30° to — 40°, with 

 the standard thermometer, Tonnelot No. 11002 (see p. 11), whose zero remained 

 unaltered during the expedition. 



The errors of the mercury sling-thermometers at low temperatures may 

 be assumed equal to the error of zero. They were made by Soderberg of 

 Stockholm, and we have seen (p. 13) that the error of Sgderberg's psychro- 

 meter-thermometers are nearly nil between 0° and — 30°. 



Toluol B was compared in January and February, 1894, and in January, 

 1895, with Tonnelot 11002, from — 23° to — 45°. The results of the two 

 series agree very well. 



Metaxylol C was compared with Tonnelot 11002 in January, 1894, from 

 — 27° to -42°. 



The corrections applied to the observed temperatures are 



