354 H. MOHN. METEOROLOGY. [2nd arc. eXp. fraM 



PART II. 



OBSERVATIONS ON BOARD THE FRAM 

 UNDER WAY. 



The meteorological observations made on board the Fram when 

 she was under way, comprised barometer, dry and wet thermometer, 

 direction and velocity of the wind, amount, form and drift of clouds, 

 precipitation, state of the sea and direction of swell or sea, and tem- 

 perature of the sea-surface. The instruments used were 



The marine barometer adie No. C. 764, the same that was on 

 board the Fram from 1893 to 1896. This barometer was found to requii'e 

 a special reduction for the temperature besides the ordinary tabular reduc- 

 tion.' It was compared with the standard barometer of the Norwegian 

 Meteorological Institute in Kristiania in 1897, and in 1902 and 1903. The 

 reductions to 0° C, and to the true barometric height, were 



in 1897 : + 0.14 + (Tab. Red. t. 0°) - 0.017 t. + 0.0007 (760~b) mm. 

 „ 1902-3: + 0.17 + (Tab. Red. t. 0°) - 0.017 t. + 0.0079 (760-b) „ 



Mean + 0.155 + (Tab. Red. t. 0°) - 0.017 t. + 0.0043. (760-b). „ 



The barometer was suspended in the fore cabin with its cistern 

 2.8 metres above the sea-surface. The reduction to sea-level is 0.285 mm. 



The gravity correction was computed by the formula b (—0.00264. 

 cos 2cp). The observations given in the following Table or Journal 

 have been reduced to 0° C, to the true height of the mercury, to sea- 

 level, and to standard gravity, by the formula 

 + 0.44 + (Tab. Red. t. 0°) - 0.017 t. + 0.0043 (760-b) + gravity correction. 



The thermometers used had been compared with standards in 1898. 

 None of them came back. They were 



1 The Norwegian Nortli Polar Expedition 1S93-1896. Scienlific Results. Edited 

 by Fridtjof Nansen. Vol. VI. pp. 7-<). 



