10 



H. MOHN. METEOROLOGY. 



[noRW. POL. EXP. 



Gravity-Correction, mm. 



The observations have been reduced to standard gravity by means of a 

 diagram constructed from the above table. The reductions for temperature, 

 constant error, and gravity were made with two decimals of a millimetre. 

 In the Tables, the reduced observations of the pressure are given to the 

 nearest tenth of a millimetre. 



The Expedition had two Barographs made by Richard in Paris. One 

 of them stood in the cabin, and continually registered the pressure of the 

 atmosphere. The clock-work was wound up and the paper changed every 

 Monday. The scale was 1 mm. = 1 mm. Further particulars will be found 

 in the chapter on the Pressure of the Air. 



TEMPERATURE OF THE AIR. THERMOMETERS. 



The expedition started with the following thermometers, destined for 

 meteorological observations : 



I. 8 mercury thermometers, made by Soderberg in Stockholm, divided 

 into 02 of a degree on paper scales hermetically inclosed, and ranging from 

 — 40° to + 40° C. Spherical bulbs. 



