338 VETTEliSSON, SIBERIAN SEA. 



that for a ccrtain dcptli the saltness appears to increase in 

 the dircction towards the lattor. Tliis nnder-ciirrent also 

 penctrates into the bed of the river itself, where its saltness 

 at a given level now no longer increases ; but neither does it 

 decrease in any sensible degree in the lowest strata. Whilo 

 the undcr-current thns proceeds at the bottom of the river, it 

 is constantly redneed in thickncss; indeed its thickness at the 

 innermost point, at whieh T could distinctly observe it, was 

 less than two feet, as niay be seen from the following special 

 series taken on the 7'^' August, 18,500 f^ above the mouth: 



Saltness in grammes on lOOO cc. 

 Jicpth in foot. of the water. 



O 0.23 



6 0.35 



8 0.40 



10 4.S3 



12 (bottom) 20.02. 



»The existence of the undcr-current was made visible by 

 means of a sunken body, which was moved by it in a contrary 

 dircction to that of the upper-stream. The water of the under- 

 currcnt wa-s clear and cold, Avhereas that of the superlicial 

 stream was very muddy, a further })roof that the under- 

 current continually rcceived fresli supplies from the liord.» 



The author thon proceeds to show, that the force, which 

 urgcs the undcr-current of salt water from the Kattegatt 

 towards the mouth of the Göta Elf, a distance of at Icast 

 12,000 metres, and thenco 5 to G kilometres up the river, 

 simultaneously raising the niveau of the salt water stratum, 

 can not be ascribcd to any difference of spec. gravity or 

 hydrostatic prcssuro, etc. . . but is due to a dynamic pheno- 

 menon, which is caused solely by the vis viva of the surface 

 current. He concludcs: 



»A river may tlicrcfore, as regards its effect upon the sca- 

 watcr at its embouchure, be compared to a pump, the piston 

 of which throws out as much water ' as it sucks up from 

 behind; the force, that sets the pump-piston in motion, here 

 corresponds to the river-waters' vis viva.^> 



1 Thip of t-ourse does not lefer to tho frosli rivor-Av;i(er itself. which 

 by its kinetic onergy sots the whole system of cnrrents in motion, but to 

 that part of the salt Mäter, wliich by adliesion or (bliusion becomes inter- 

 mingled with the river-water insido or ontside its embouchure and. partaking 

 of its motion, is sprea<l further över tho surface of the sea. This water 

 natnrally requires to be supplied by sea water either from the side or from 

 below. Hence the under-current. 



