Introductory remarks. 



Diiring the voyage of the Vega along the Siberian coast 

 great attention was paid to the hydrographic constitution of 

 the sea. Beside the regular observations at midnight, 4 & 8 

 a.m., noon, 4 & 8 p.in., of the temperature and density of the 

 water at the surface, which are registered in the meteorological 

 journal, a serial deep-sounding was made at least once a day 

 by means of the isolating apparatus invented by Professor F. 

 L. Ekman. This instrument is too well known by professional 

 experimenters and students of hydrograph}^ to need any de- 

 scription here. For a shallow sea, Hke the Siberian (the depth 

 of which nowliere exceeds 200 metres), with very variable 

 water-strata, it is indeed unequalled. Immediately after the 

 isolated capsule, containing a sample of water from a certain 

 depth had been hauled on board, the temperature of the water 

 was determined with a thermometer ^ and its density with an 

 areometer manufactured by A der man. 



Lieutenant G. Bo ve of the R. Italian Navy had tlie man- 

 agement of the hydrographic operations during the expedition. 

 I have calculated the following results from his annotations 

 in the hydrographic journal of the Vega. 



The observations are regularly registered in the journal 

 from the departure of the Vega from Yugor Schar, the southern 

 ^ntrance to the Kära Sea, on the 1*' August, 1878, until the 

 arrival at Koljutchin bay on the 23'"'^ Sept., about 119' from 

 the Behring- strait. During the winter some observations 

 concerning the temperature of the sea-water, the thickness of 

 the ice etc. . . were made by various members of the expedi- 

 tion. Some of these observations I have discussed in the. 

 preceding paper. The regular series of hydrographic annota- 



' This instrument is graduated in -/i„ of a centigrade, althougli ' i„ 

 can be easily estimated by the observer. It is of very elaborate workman- 

 ship and possesses the remarkable advantage of an ahnost steady point of 

 zero. like most of the Åder man thermometers. 



