Hydrographical Observations from the Danmark Expedition. 



393 



On September lOth 1907 the rivers again became frozen over 

 and on September 18th new ice formed round about the ship. This 

 increased regularly in thickness, but less than in 1906. 



The surface salinity increased in a similar manner as in 1906, 

 comparatively most in the autumn. 



The thickness of the ice reached its maximum in the middle of 

 February and 

 thereafter decreas- 

 ed evenly in con- 

 trast to what oc- 

 curred in the pre- 

 ceding winter, 

 when the thickness 

 of the ice had re- 

 mained unchanged 

 for a long time. 

 The salinity, how- 

 ever, continued to 

 increase until the 

 beginning of June, 

 when the air tem- 

 perature became 

 positive and the 

 water from the 

 melting snow and 



ice came down 

 from the land. 



On June 18th 

 1908 the rivers 

 broke up and on 

 July 4th the ice 

 had melted round 

 about the ship. 



The differen- 

 ces in the thick- 

 ness of the ice in 

 the two Nxinters 



and in the rapidity with which it melted in the two following summers 

 were due to the following causes. 



1. Different heat conditions in the sea outside the coast. 



2. Difference in the amount of warmed water from the melting 

 snow and ice in the spring. 



3. Difference in the meteorological conditions, snowfall and 

 the like in the autumn which affected especially the structure of 

 the ice. 







^"^^ 





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Fig. 9. Stern of the "Danmark". Tidal fissure seen 

 below; С В. Thostrup phot. 



