With regard to the temperature conditions here mentioned, Captain 

 Baumann, upon inquiry, has given a verbal explanation, which is very 

 much as follows. 



The summer temperature on shore, where the magnetic observations 

 were made, was ahvays much higher than out on the vessel. The sun 

 was really scorching when there was no wind, so much so, that the 

 observer sometimes had to divest himself of various articles of clothing. 

 Even when the tent was used, the sun might shine directly upon the 

 instrument through the tent-door, which always faced south. The vibration- 

 box, which had a black bottom, became especially warm, and this 

 heated the air and the magnet in the box. The air in the tent was 

 warmed by the heated sides of the tent. The fact that the temperature 

 during the deflections never reached so high a point as the vibration- 

 temperatures, may presumably be explained by the circumstance that 

 the thermometer used in the deflections was bent in such a manner, 

 that the bulb was in the zinc casing that was placed over the deflector, 

 and was not exposed to the direct radiation of heat from the sun itself 

 or the sides of the tent. 



The considerable and often rapid variations of temperature are 

 probably caused by the occurrence of strong gusts of wind. A cold wind 

 would often suddenly blow from the nearest elevated ice-covered land- 

 surface (glacier), and cool the instrument and the tent, especially when 

 at the same time the sun was hidden by clouds. 



Captain Baumann added that once during a sledge-journey he ob- 

 served with a "sling-thermometer an air temperature of — 25° C, while 

 at the same time the sun was powerful enough to melt the surface of 

 the ice, where pools of water appeared. 



